Review Cards - Clinical Chemistry Flashcards
Reference range: Bilirubin, total
0.2-1 mg/dL
SI units: 3.4-17.1 umol/L
Reference range: BUN
6-20 mg/dL
SI units: 2.1-7.1 mmol/L
Reference range: Calcium, total
8.6-10 mg/dL
SI units: 2.15-2.5 mmol/L
Reference range: Chloride
98-107 mEq/L
SI units: 98-107 mmol/L
Reference range: Creatinine
0.6-1.2 mg/dL
SI units: 53-106 mmol/L
Values can vary between males and females
Reference range: Glucose, fasting
70-99 mg/dL
SI units: 3.9-5.5 mmol/L
Reference range: Potassium
3.5-5.1 mEq/L
SI units: 3.5-5.1 mmol/L
Reference range: Potassium
3.5-5.1 mEq/L
SI units: 3.5-5.1 mmol/L
Reference range: Sodium
136-145 mEq/L
SI units: 136-145 mmol/L
Reference range: Total protein
6.4-8.3 g/dL
SI units: 64-83 g/L
Reference range: Uric acid
Male: 3.5-7.2 mg/dL
Female: 2.6-6 mg/dL
SI units:
Male: 208-428 umol/L
Female: 155-357 umol/L
Diurnal variation - analytes affected?
Increased in AM: ACTH, cortisol, iron
Increased in PM: growth hormone, PTH, TSH
Day-to-day variation - analytes affected?
> =20% for alanine aminotransferase (ALT), bilirubin, creatinine kinase, steroid hormones, triglycerides
Recent food ingesting - analytes affected?
Increased: glucose, insulin, gastrin, triglycerides, sodium, uric acid, iron, lactate dehydrogenase, calcium
Decreased: chloride, phosphate, potassium
Fasting required: fasting glucose, triglycerides, lipid panel
Alcohol - analytes affected?
Decreased: glucose
Increased: cholesterol, gamma glutamyl transferase (GGT)
Posture - analytes affected?
Increased: albumin, cholesterol, calcium
(when standing)
Activity - analytes affected?
Increased in ambulatory patients: creatinine kinase (CK)
Increased with exercise: potassium, phosphate, lactic acid, creatinine, protein, CK, aspartate, aminotransferase (AST), LD
Stress - analytes affected?
Increased: ACTH, cortisol, catecholamines
Age, gender, race, drugs - analytes affected?
Various
Use of isopropyl alcohol wipes to disinfect venipuncture site - effect?
can compromise blood alcohol determination
squeezing site of capillary puncture - effect?
increased potassium
pumping fist during venipuncture - effect?
increased: potassium, lactic acid, calcium, phosphorus
decreased: pH
Tourniquet >1 minute - effect?
increased: potassium, total protein, lactic acid
IV fluid contamination - effect?
Increased: glucose, potassium, sodium, chloride (depending on IV)
Possible dilution of other analytes.
Incorrect anticoagulant or contamination from incorrect order of draw - effect?
K2EDTA:
decreased calcium, magnesium
increased potassium
Sodium heparin: increased sodium if tube is not completely filled
Lithium heparin: increased lithium
Gels: some interfere with trace metals & certain drugs
Hemolysis - effect?
Increased potassium, magnesium, phosphorus, LD, AST, iron, ammonia
(May be method dependent. Refer to reagent package inserts.)
Exposure to light - effect?
decreased bilirubin
Temperature between collection & testing - effect?
chilling required for lactic acid, ammonia, blood gases
Inadequate centrifugation - effect?
poor barrier formation in gel tubes can result in increased: potassium, LD, AST, iron, phosphorus
Recentrifugation of primary tubes - effect?
hemolysis
Increased potassium
Delay in separating serum/plasma (unless gel tube is used) - effect?
Increased: ammonia, lactic acid, potassium, magnesium, LD
Decreased: glucose (unless collected in fluoride)
Storage temperature - effect?
Decreased at RT: glucose (unless collected in fluoride)
Increased at RT: lactic acid, ammonia
Decreased at 4*C: LD
Increased at 4*C: alkaline phosphatase (ALP)
Higher in plasma than serum
Total protein
LD
Calcium
Higher in serum than plasma
Potassium
Phosphate
Glucose
CK
Bicarbonate
ALP
Albumin
AST
Triglycerides
Higher in plasma than whole blood
Glucose
Higher in capillary blood than venous blood
Glucose (in postprandial specimen)
Potassium
Higher in venous blood than capillary blood
Calcium
Total protein
Higher in RBCs than plasma
Potassium
Phosphate
Magnesium
Higher in plasma than RBCs
Sodium
Chloride
Spectophotometry - principle?
A chemical reaction produces a colored substance that absorbs light of a specific wavelength.
The amount of light absorbed is directly proportional to the concentration of the analyte.
Spectrophotometry - component parts?
1.Light source:
a. Tungsten lamp - visible range
b. Deuterium lamp - UV range
2. Monochromator - diffraction grating
3. Cuvette
4. Photodetector
5. Readout device
Atomic absorption spectrophotometry - principle?
Measures light absorbed by ground-state atoms.
Hollow cathode lamp with cathode made of analyte produces wavelength specific for analyte.
Used to measure TRACE METALS.
Atomic absorption spectrophotometry - component parts?
- Hollow cathode lamp
- Atomizer
- Flame
- Mixing chamber
- Chopper
- Monochromator
- Detector
- Readout device
Fluorometry - principle?
Atoms absorb light of a specific wavelength & emit light of a longer wavelength (lower energy)
Detector at 90* to the light source so that only light emitted by the sample is measured.
More sensitive than colorimetry.
Used to measure DRUGS, HORMONES.
Fluorometry - component parts?
- Light source - mercury or xenon arc lamp
- Primary monochromator
- Sample holder (quartz cuvettes)
- Secondary monochromator
- Detector
- Readout device
Chemiluminescence - principle?
Chemical reaction that produces light. Usually involves oxidation of luminol, acridinium esters, or dioxetanes.
Doesn’t require excitation radiation or monochromators like fluorometry. Extremely sensitive. Used for immunoassays.
Chemiluminescence - component parts?
- Reagent probes
- Sample & reagent cuvettes
- Photomultiplier tube
- Readout device
Turbidimetry - principle?
Measures the reduction in light transmission by particles in suspension.
Used to measure proteins in urine & CSF.
Nephelometry - principle?
Similar to turbidimetry, but light is measured at an angle from the light source.
Used to measure antigen-antibody reactions.
Turbidimetry - component parts?
- Light source
- Lens
- Cuvette
- Photodetector
- Readout device
Nephelometry - component parts?
- Light source
- Collimator
- Monochromator
- Cuvette
- Photodetector
- Readout device
Visible light spectrum: 350-430 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Violet
Transmitted: Yellow
Visible light spectrum: 430-475 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Blue
Transmitted: Orange
Visible light spectrum: 475-495 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Blue-green
Transmitted: Red-orange
Visible light spectrum: 495-505 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Green-blue
Transmitted: Orange-red
Visible light spectrum: 505-555 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Green
Transmitted: Red
Visible light spectrum: 555-575 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Yellow-green
Transmitted: Violet-red
Visible light spectrum: 575-600 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Yellow
Transmitted: Violet
Visible light spectrum: 600-650 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Orange
Transmitted: Blue
Visible light spectrum: 670-700 nm
Color absorbed?
Color transmitted (visible)?
Absorbed: Red
Transmitted: Green
Wavelengths used in Spectrophotometry: 220-380 nm
Range?
Common light source?
Cuvette?
Range: near-ultraviolet
Light source: deuterium or mercury arc
Cuvette: Quartz (silica)
Wavelengths used in Spectrophotometry: 380-750 nm
Range?
Common light source?
Cuvette?
Range: visible
Light source: Incandescent tungsten OR tungsten-iodide
Cuvette: Borosilicate
Wavelengths used in Spectrophotometry: 750-2,000 nm
Range?
Common light source?
Cuvette?
Range: Near-infrared
Light source: Incandescent tungsten OR tungsten-iodide
Cuvette: Quartz (silica)
Separation of compounds based on different distribution between mobile phase & stationary phase
Chromatography
Thin-layer chromatography - components?
- Sorbent-coated glass or plastic plate
- Closed container
- Solvent
Thin-layer chromatography - use?
Screening for drugs of abuse in urine
Thin-layer chromatography - how are substances identified?
by retention factor (R1) value - distance traveled by compound/distance traveled by solvent
High-performance liquid chromatography (HPLC) - components?
- Solvent
- Pump
- Injection port
- Column
- Detector
- Recorder
High-performance liquid chromatography - use?
separation of thermolabile compounds
High-performance liquid chromatography - how is concentration determined?
by peak height ratio (height of analyte peak/height of internal standard peak)
High-performance liquid chromatography - what can be used as a detector for definitive identification?
mass spectrometry (MS)
(LC/MS)
Gas chromatography - components?
- Gas
- Injection port
- Column
- Oven
- Detector
- Recorder
Gas chromatography - use?
separation of volatile compounds or compounds that can be made volatile, e.g., therapeutic & toxic drugs
Gas chromatography - what are compounds identified by?
retention time
(area of peak is proportional to concentration)
MS can be used as detector for definitive ID (GC/MS).
Ion-selective electrodes - principle?
Potential difference between 2 electrodes is directly related to the concentration of the analyte.
Ion-selective electrodes - component parts?
- Reference electrode
- Indicator electrode
- Liquid junction
- Measuring device
Ion-selective electrodes - Use?
pH
PCO2
PO2
Sodium
Potassium
Calcium
Lithium
Chloride
Osmometry - principle?
Determines osmolality based on freezing-point depression.
Measurement of the number of dissolved particles in solution, irrespective of molecular weight, size, density, or type.
Osmolality
Osmometry - component parts?
- cooling bath
- thermistor
- probe
- stirring wire
- galvanometer
Osmometry - use?
Serum & urine osmolality
Electrophoresis - principle?
Separation of charged particles in an electrical field.
Anions move to positively charged pole (anode); cations move to negatively charged pole (cathode).
The greater the charge, the faster the migration.
Electrophoresis - component parts?
- Power supply
- Support medium
- Buffer
- Stain
- Densitometer
Electrophoresis - use?
Serum protein electrophoresis
Hemoglobin electrophoresis
Mass spectrometry - principle?
Generates multiple ions from the sample, then separates them according to their mass to charge ratio (m/z).
Extremely sensitive and specific.
Mass spectrometry - component parts?
- Ion source
- Analyzer
- Detector system
Mass spectrometry - use?
Drugs of abuse
Newborn screening
Hormones
Vitamins
Steroid analysis
Basic metabolic panel
Sodium
Potassium
Chloride
CO2
Glucose
Creatinine
BUN
Calcium
Comprehensive metabolic panel
Sodium
Potassium
Chloride
CO2
Glucose
Creatinine
BUN
Calcium
Albumin
Total protein
ALP
AST
Bilirubin
Electrolyte panel
Sodium
Potassium
Chloride
CO2
Hepatic function panel
Albumin
ALT
AST
ALP
Bilirubin (total & direct)
Total protein
Lipid panel
Total cholesterol
HDL
LDL
Cholesterol
Triglycerides
Renal function panel
Sodium
Potassium
CO2
Glucose
Creatinine
BUN
Calcium
Albumin
Phosphate
Glucose, fasting - reference range?
Normal: <100 mg/dL
(5.6 mmol/L)
Hyperglycemia - clinical significance?
Diabetes mellitus
Other endocrine disorders
Acute stress
Pancreatitis
analyte that is a major source of cellular energy
Glucose
Hypoglycemia - clinical significance?
Insulinoma
Insulin-induced hypoglycemia
Hypopituitarism
Is glucose increased or decreased at RT?
decreased
Which additive should be used when collecting blood for glucose to prevent glycolysis?
Sodium fluoride
Most common methods of determining glucose concentration?
glucose oxidase & hexokinase
Hexokinase = more accurate due to fewer interfering substances
Cholesterol, total - Reference range?
Desirable: <150 mg/dL
(5.2 mmol/L)
Cholesterol, total - clinical significance?
Limited value for predicting risk of coronary artery disease (CAD) by itself.
Used in conjunction with HDL & LDL cholesterol.
Most common method for measuring total cholesterol?
Enzymatic methods
HDL cholesterol - reference range?
Desirable: >=60 mg/dL
(1.5 mmol/L)
HDL cholesterol - clinical significance?
Appears to be inversely related to CAD.
Assays used to measure HDL cholesterol?
Homogenous assays - don’t require pretreatment to remove non-HDL
1st reagent - blocks non-HDL
2nd reagent - reacts with HDL
LDL cholesterol - reference range?
Optimal: <100 mg/dL
(2.6 mmol/L)
LDL cholesterol - clinical significance?
Risk factor for CAD
How is LDL concentration determined?
May be calculated from the Friedewald formula (if triglycerides are not >400 mg/dL) OR measured by direct homogenous assays.
Triglycerides - reference range?
Desirable: <150 mg/dL
(1.7 mmol/L)
Triglycerides - clinical signfiicance?
Risk factor for CAD.
What is the main form of lipid storage?
Triglycerides
Methods used for measuring triglyceride levels?
Enzymatic methods using lipase.
(Requires a fasting specimen)
Total protein - reference range?
6.4-8.3 g/dL
64-83 g/L
Increased total protein - clinical significance?
dehydration
chronic inflammation
multiple myeloma
Decreased total protein - clinical significance?
nephrotic syndrome
malabsorption
overhydration
hepatic insufficiency
malnutrition
agammaglobulinemia
What concentration of total protein is associated with peripheral edema?
<4.5 g/dL
Method of measuring total protein?
Biuret method
(Alkaline copper reagent reacts with peptide bonds)
Albumin - reference range?
3.5-5 g/dL
35-50 g/L
Decreased albumin - clinical significance?
dehydration
Increased albumin - clinical significance?
malnutrition
liver disease
nephrotic syndrome
chronic inflammation
What is the largest fraction of plasma proteins?
Albumin
Where is albumin synthesized?
liver
What is the function of albumin?
regulates osmotic pressure
How is albumin measured?
dye binding, e.g., bromocresol green (BCG), bromocresol purple (BCP)
Microalbumin (performed on urine sample) - reference range?
30-300 mg/24 hr
What is microalbuminuria predictive of?
diabetic nephropathy
Microalbumin - clinical significance?
increased in diabetics at risk of nephropathy
detects albumin in urine earlier than dipstick protein
microalbumin
alternative to measuring microalbumin in a 24 hr urine sample
albumin-to-creatinine ratio on a random sample
hormone that decreases glucose levels
insulin
action of insulin
responsible for entry of glucose into cells; increases glycogenesis
hormones that increase glucose levels
Glucagon
Cortisol
Epinephrine
Growth hormone
Thyroxine
responsible for entry of glucose into cells; increases glycogenesis
insulin
insulin antagonist; increases gluconeogenesis
cortisol
promotes glycogenolysis & gluconeogenesis
epineprhine
insulin antagonist
growth hormone
increases glucose absorption from GI tract; stimulates glycogenolysis
thyroxine
Type I diabetes mellitus - cause?
autoimmune destruction of beta cells
genetic predisposition - HLA-DR 3/4
absolute insulin deficiency; prone to ketoacidosis & diabetic complications
Type 1 DM
Type 2 diabetes mellitus - cause?
Insulin resistance in peripheral tissues.
-insulin secretory defect of beta cells
-associated with obesity
Gestational diabetes mellitus - cause?
placental lactogen inhibits action of insulin
GDM - risk to fetus?
death or neonatal complications - macrosomia, hypoglycemia, hypocalcemia, polycythemia, hyperbilirubinemia
When is GDM usually diagnosed?
during later 1/2 of pregnancy
Pre-diabetes - cause?
patients unable to utilize glucose efficiently but are not yet considered fully diabetic
Tests for DM - random plasma glucose
Pre-diabetes?
DM?
Pre-diabetes: none
DM: >=200 mg/dL
(>11.1 mmol/L)
When is a random plasma glucose test used?
only for use in patients with symptoms of hyperglycemia
Tests for DM - fasting plasma glucose (FPG)
Pre-diabetes?
DM?
Pre-diabetes: 100-125 mg/dL
DM: >=126 mg/dL
Tests for DM - oral glucose tolerance tests (OGTT)
Pre-diabetes?
DM?
140-199 mg/dL - 2 hours post-glucose ingestion indicates pre-diabetes
DM: Fasting >=95 mg/dL OR 1 hour >=180 mg/dL, OR 2 hr >=155 mg/dL
When is an OGTT test performed during pregnancy?
24-28 weeks gestation
Tests for DM - Hemoglobin A1C
Pre-diabetes?
DM?
Pre-diabetes: 5.7-6.4%
DM: >=6.5%
gives estimate of glucose control over previous 2-3 months
hemoglobin A1C
When should a hemoglobin A1C not be used?
patients with hemoglobinopathies or abnormal RBC turnover
Typical laboratory findings in uncontrolled DM:
Increased?
Decreased?
Increased:
1. blood glucose
2. urine glucose
3. urine SG
4. glycohemoglobin
5. ketones (blood & urine)
6. anion gap
7. BUN
8. Osmolality (serum & urine)
9. Cholesterol
10. Triglycerides
Decreased:
1. Bicarbonate
2. Blood pH
Metabolic syndrome - definition?
group of risk factors that seem to promote development of atherosclerotic cardiovascular disease & type 2 diabetes mellitus
Metabolic syndrome - risk factors?
decreased HDL-C
increased LDL-C
increased triglycerides
increased blood pressure
increased blood glucose
Aminoacidopathies - Phenylketonuria - cause?
deficiency of the enzyme that converts phenylalanine to tyrosine
phenylpyruvic acid in blood & urine
Aminoacidopathies - Phenylketonuria - effect?
mental retardation
Aminoacidopathies - Phenylketonuria - urine?
“mousy” odor
Aminoacidopathies - Phenylketonuria - diagnosis?
Guthrie bacterial inhibition assay, HPLC, tandem mass spectrometry (MS/MS), fluorometric & enzymatic methods.
All newborns are screened.
Aminoacidopathies - Tyrosinemia - cause?
disorder of tyrosine catabolism - tyrosine and its metabolites are excreted in urine
Aminoacidopathies - Tyrosinemia - effect?
Liver & kidney disease, death
Aminoacidopathies - Tyrosinemia - diagnosis?
MS/MS
Aminoacidopathies - Alkaptonuria - cause?
Deficiency of the enzyme needed in the metabolism of tyrosine & phenylalanine; buildup of homogentisic acid
Aminoacidopathies - Alkaptonuria - effect?
diapers stain black due to homogentisic acid in urine
later in life - darkening of tissues, hip & back pain
Aminoacidopathies - Alkaptonuria - diagnosis?
Gas chromatography & mass spectroscopy
Aminoacidopathies - Maple syrup urine disease (MSUD) - cause?
enzyme deficiency leading to the buildup of leucine, isoleucine, and valine
Aminoacidopathies - Maple syrup urine disease (MSUD) - effect?
Burnt-sugar odor to urine, breath, & skin.
Failure to thrive, mental retardation, acidosis, seizures, coma & death
Aminoacidopathies - Maple syrup urine disease (MSUD) - diagnosis?
Modified Guthrie test, MS/MS
Aminoacidopathies - Homocystinuria - cause?
deficiency in the enzyme needed for the metabolism of methionine; methionine & homocysteine buildup in plasma & urine
Aminoacidopathies - Homocystinuria - effect?
osteoporosis
dislocated lenses in the eye
mental retardation
thromboembolic events
Aminoacidopathies - Homocystinuria - diagnosis?
Guthrie test, MS/MS, LC-MS/MS
Aminoacidopathies - Cystinuria - cause?
Increased excretion of cystine due to defect in renal reabsorption
Aminoacidopathies - Cystinuria - effect?
recurring kidney stones
Aminoacidopathies - Cystinuria - diagnosis?
test urine with cyanide nitroprusside:
pos = red-purple color
Protein electrophoresis - rate of migration?
depends on size, shape, & charge of molecule
Protein electrophoresis - support medium?
cellulose acetate or agarose
Protein electrophoresis - buffer?
barbital buffer, pH 8.6
Protein electrophoresis - stains?
Ponceau S
amido blue
bromphenol blue
Coomassie brilliant blue
Protein electrophoresis - charge?
At pH 8.6, proteins are negatively charged & move toward the anode
Protein electrophoresis - order of migration (fastest to slowest)?
Albumin
alpha-1 globulin
alpha-2 globulin
beta globulin-1
beta globulin-2
gamma globulin
Protein electrophoresis - largest fraction?
albumin
Protein electrophoresis - electroendosmosis?
buffer flow toward cathode - causes gamma region to be cathodic to point of application
Protein electrophoresis - urine?
Must be concentrated first because of low protein concentration.
Bence-Jones proteins migrate to the gamma region in urine electrophoresis.
Protein electrophoresis - CSF?
Must be concentrated first because o flow protein concentration.
CSF has a prealbumin band.
Common serum protein electrophoresis patterns - normal
Common serum protein electrophoresis patterns - acute inflammation
Decreased albumin
Increased alpha-1 & alpha-2
Common serum protein electrophoresis patterns - chronic infection
Increased alpha-1, alpha-2, and gamma
Common serum protein electrophoresis patterns - cirrhosis
Polyclonal increase (all fractions) in gamma with beta-gamma bridging
Common serum protein electrophoresis patterns - monoclonal gammopathy
Sharp increase in 1 immunoglobulin (“M spike”), decrease in other fractions
Common serum protein electrophoresis patterns - polyclonal gammopathy
Diffuse increase in gamma
Common serum protein electrophoresis patterns - hypogammaglobulinemia
decreased gamma
Common serum protein electrophoresis patterns - nephrotic syndrome
decreased albumin
increased alpha-2
Common serum protein electrophoresis patterns - alpha-1-antitrypsin deficiency
decreased alpha-1
Common serum protein electrophoresis patterns - hemolyzed specimen
increased beta or unusual band between alpha-2 & beta
Common serum protein electrophoresis patterns - plasma
extra band (fibrinogen) between beta & gamma
List the nonprotein nitrogen compounds.
- BUN
- Creatinine
- Uric acid
- Ammonia
BUN - reference range?
8-26 mg/dL
(2.1-7.1 mmol/L)
BUN - clinical significance?
Increased - kidney disease
Decreased - overhydration or liver disease
How is BUN synthesized?
by the liver from ammonia
How is BUN excreted?
by the kidneys
BUN - reagent?
Urease
Which anticoagulants should not be used to collect a BUN sample?
sodium fluoride
EDTA
citrate
ammonium heparin
How is BUN measured?
Utilizes urease reaction, measure decrease in absorbance at 340 nm
How should a BUN urine specimen be stored?
Dilute urine 1:20 or 1:50 & refrigerate or acidify
Creatinine - reference range?
0.6-1.2 mg/dL
(53-106 mmol/L)
Creatinine - clinical significance?
Increased - kidney disease
waste product from dehydration of creatine (mainly in muscles)
creatinine
Creatinine - method of measurement?
Jaffe reaction (alkaline picrate) is nonspecific but kinetic version increases specificity; enzymatic methods are more specific.
Dilute urine 1:100.
normal BUN:creatinine ratio
12-20
Uric acid - reference range?
Male: 3.5-7.2 mg/dL
Female: 2.6-6 mg/dL
Uric acid - clinical significance?
increased - gout, renal failure, ketoacidosis, lactate excess, high nucleoprotein diet, leukemia, lymphoma, polycythemia
decreased - administration of ACTH, renal tubular defects
What does elevated uric acid increase the risk of developing?
renal calculi
Uric acid - method of measurement?
analyzed with uricase method
EDTA & fluoride interfere
adjust urine pH to 7.5-8 to prevent precipitation
Ammonia - reference range?
19-60 mcg/dL
Ammonia - clinical significance?
Increased - liver disease, hepatic coma, renal failure, Reye syndrome
High levels of what nonprotein nitrogen compound are neurotoxic?
ammonia
What anticoagulant tubes should be used when testing for ammonia?
EDTA or heparin
Why should serum not be used when testing for ammonia?
serum may cause increased levels as NH3 is generated during clotting
How should specimens for ammonia be collected?
EDTA or heparin tubes
Chilled immediately
Analyzed ASAP
Avoid contamination from ammonia from detergents or water
List the major electrolytes.
- sodium
- potassium
- chloride
- CO2, total
Sodium - reference range?
136-145 mmol/L
Sodium - clinical significance - hypernatremia
Increased intake
IV administration
hyperaldosteronism
excessive sweating
burns
diabetes insipidus
-causes tremors, irritability, confusion, coma
Sodium - clinical significance - hyponatremia
Renal or extrarenal loss (vomiting, diarrhea, sweating, burns)
Increased extracellular fluid volume
-causes weakness, nausea, altered mental status
What is the major extracellular cation?
Sodium
What electrolyte contributes almost half to plasma osmolality?
Sodium
Function of sodium in the body
maintains normal distribution of water & osmotic pressure
What are sodium levels regulated by?
aldosterone
Sodium- method of measurment
ion-selective electrode (ISE)
What is the normal sodium/potassium ratio in serum?
30:1
Potassium - reference range?
3.5-5.1 mmol/L
Potassium - clinical significance - hyperkalemia
increased intake
decreased excretion
crush injuries
metabolic acidosis
-can cause muscle weakness, confusion, cardiac arrhythmia, cardiac arrest
Potassium - clinical significance - hyperkalemia
increased GI or urinary loss
use of diuretics
metabolic alkalosis
-can cause muscle weakness, paralysis, breathing problems, cardiac arrhythmia, death
What is the major intracellular cation?
potassium
What can cause a artificial increase in potassium?
squeezing site of capillary puncture
prolonged tourniquet
pumping fist during venipuncture
contamination with IV fluid
hemolysis
prolonged contact with RBCs
leukocytosis
thrombocytosis
Why are serum potassium values 0.1-0.2 mmol/L HIGHER than plasma?
Due to release from platelets during clotting
Potassium - method of measurement
Ion selective electrode (ISE) with vancomycin membrane
Chloride - reference range?
98-107 mmol/L
Chloride - clinical significance - hyperchloremia
increased intake
IV administration
hyperaldosteronism
excessive sweating
burns
diabetes insipidus
excess loss of HCO3-
Chloride - clinical significance - hypochloremia
prolonged vomiting
diabetic ketoacidosis
aldosterone deficiency
salt-losing renal diseases
metabolic alkalosis
compensated respiratory acidosis
What is the major extracellular ion?
Chloride
Function of chloride
helps maintain osmolality, blood volume, electric neutrality
What passively follows sodium?
Chloride
Chloride - method of measurement
ISE
What test is used for the diagnosis of cystic fibrosis?
Sweat chloride test
CO2, total - reference range
23-29 mmol/L
CO2, total - clinical significance - increased
metabolic alkalosis
compensated respiratory acidosis
CO2, total - clinical significance - decreased
metabolic acidosis
compensated respiratory alkalosis
In what form is most CO2?
> 90% bicarbonate (HCO3-)
-remainder is carbonic acid (H2CO3) & dissolved CO2
Function of HCO3-
maintain acid-base balance
Why should you keep a sample being tested for CO2 capped?
to prevent loss of CO2
CO2, total - method of measurement
ISE or enzymatic method
Magnesium - reference range
1.6-2.6 mg/dL
Magnesium - clinical significance - increased
renal failure
increased intake (e.g., antacids)
dehydration
bone cancer
endocrine disorders
-can cause cardiac abnormalities, paralysis, respiratory arrest, coma
Magnesium - clinical significance - decreased
severe illness
GI disorders
endocrine disorders
renal loss
-can lead to cardiac arrhythmias, tremors, tetany, paralysis, psychosis, coma
-rare in non-hospitalized patients
Function of magnesium
essential cofactor for many enzymes
What electrolyte is 10x more concentrated in RBCs?
magnesium
Which anticoagulants/additives should be avoided when collecting a specimen for magnesium? Why?
EDTA, citrate, oxalate
-they bind magnesium
Does hemolysis affect magnesium test results?
yes
Calcium - reference range
Total: 8.6-10 mg/dL
Ionized: 4.60-5.08 mg/dL
Calcium - clinical significance - increased
primary hyperparathyroidism
cancer
multiple myeloma
-can cause weakness, coma, GI symptoms, renal calculi
Calcium - clinical significance - decreased
hypoparathyroidism
malabsorption
vitamin D deficiency
renal tubular acidosis
-leads to tetany (muscle spasms), seizures, cardiac arrhythmias
What is the most abundant mineral in the body?
calcium
99% in bones
What is calcium regulated by?
PTH
vitamin D
calcitonin
Magnesium - method of measurement
colorimetric methods
What anticoagulant/additives should be avoided when collecting a specimen for calcium? Why?
all except heparin
-they bind calcium
Calcium (total) - method of measurement
Colorimetric methods
What is the biologically active form of calcium and a better indicator of calcium status?
ionized (free) calcium
Calcium (ionized) - method of measurement
ISE
What factors affect the results of calcium measurement?
pH
temp
Phosphorus, inorganic (phosphate) - reference range
2.5-4.5 mg/dL
Phosphorus, inorganic (phosphate) - clinical significance - increased
renal disease
hypoparathyroidism
Phosphorus, inorganic (phosphate) - clinical significance - decreased
hyperparathyroidism
vitamin D deficiency
renal tubular acidosis
What is the major extracellular anion?
Phosphorus
Where in the body is most phosphorus located?
bones
Function of phosphorus
component of nucleic acids and many coenzymes
important reservoir of energy (ATP)
Phosphorus results are a limited value alone. What should results be correlated with?
calcium
(normally a reciprocal relationship)
True or False. Phosphorus is higher in children than adults.
True
Which anticoagulants/additives interfere with phosphorus results?
citrate
oxalate
EDTA
Is phosphorus higher in RBCs or plasma?
RBCs
Does hemolysis affect phosphorus results?
yes
Lactate (lactic acid) - reference range
4.5-19.8 mg/dL
Lactate (lactic acid) - clinical significance
sign of decreased O2 to tissues
What is lactate (lactic acid) a byproduct of?
anaerobic metabolism
Lactate (lactic acid) - collection considerations
Best NOT to use a tourniquet.
Patient should not make a fist.
Collect in heparin & put on ice OR use fluoride to inhibit glycolysis.
Lactate (lactic acid) - method of measurement
enzymatic methods
Iron - reference range
Males: 65-175 mcg/dL
Females: 50-170 mcg/dL
Iron- clinical significance - increased
iron overdose
hemochromatosis
sideroblastic anemia
hemolytic anemia
liver disease
Iron - clinical significance - decreased
iron deficiency anemia
What analyte is necessary for hemoglobin synthesis?
Iron
How is iron transported in the body?
by transferrin
Does hemolysis interfere with iron testing?
yes
Which anticoagulants/additives should be avoided when collecting a specimen for iron? Why?
Oxalate, citrate, EDTA
-they bind iron
Why is an early morning specimen preferred for iron testing?
because of diurnal variation
Iron - method of measurement
Colorimetric methods
Total iron binding capacity (TIBC) - reference range
250-425 mcg/dL
Total iron binding capacity (TIBC) - clinical significance - increased
iron deficiency anemia
Total iron binding capacity (TIBC) - clinical significance - decreased
iron overdose
hemochromatosis
Total iron binding capacity (TIBC) - method of measurement
Iron is added to saturate transferrin. The excess is removed. Then iron content is determined.
% saturation or transferrin saturation - reference range
20-50%
% saturation or transferrin saturation - clinical significance - increased
iron overdose
hemochromatosis
sideroblastic anemia
% saturation or transferrin saturation - clinical significance - decreased
iron deficiency anemia
% saturation or transferrin saturation - method of measurement
Calculated value.
Transferrin - reference range
200-360 mg/dL
Transferrin - clinical significance - increased
iron deficiency anemia
Transferrin - clinical significance - decreased
iron overdose
hemochromatosis
chronic infections
malignancies
What is transferrin?
Complex of apotransferrin (protein that transports iron) and iron.
Transferrin - method of measurement
immunoassay
Ferritin - reference range
Males: 20-250 mcg/L
Females: 10-120 mcg/L
Ferritin - clinical significance - increased
iron overload
hemochromatosis
chronic infections
malignancies
Ferritin - clinical significance - decreased
iron deficiency anemia
What is the storage form of iron?
ferritin
rough estimate of body iron content
ferritin
Ferritin - method of measurement
immunoassay
List the factors that influence enzymatic reactions.
- substrate concentration
- enzyme concentration
- pH
- temperature
- cofactors
- inhibitors
Factors that influence enzymatic reactions - substrate concentration - first-order kinetics
[enzyme] > [substrate]
Reaction rate is proportional to [substrate].
Factors that influence enzymatic reactions - substrate concentration - zero-order kinetics
[substrate] > [enzyme]
Reaction rate is proportional to [enzyme].
Factors that influence enzymatic reactions - enzyme concentration
velocity of the reaction is proportional to [enzyme] as long as [substrate] > [enzyme]
Factors that influence enzymatic reactions - enzyme concentration - unit of measure
international unit (IU)
Factors that influence enzymatic reactions - enzyme concentration - enzyme catalytic activity measurement
the amount of enzyme that will catalyze 1 umol of substrate per minute under standardized conditions
Factors that influence enzymatic reaction - pH
extremes of pH may denature enzymes
Most reactions occur at pH 7-8.
Use buffers to maintain optimal pH.
Factors that influence enzymatic reactions - temperature
Increases of 10C doubles the rate of reaction until around 40-50C; then denaturation of enzyme may occur.
37*C is most commonly used in the US.
Factors that influence enzymatic reactions - cofactors
nonprotein organic molecules that participate in reactions.
Must be present in excess.
Factors that influence enzymatic reactions - cofactors - organic
called coenzymes - may serve as 2nd substrate in the reaction
(e.g., nicotinamide adenine nucleotide)
Factors that influence enzymatic reactions - cofactors - inorganic
called activators - either required for OR enhance reaction
(e.g., chloride, magnesium)
Factors that influence enzymatic reactions - cofactors - reaction most commonly used in enzyme determinations
NAD <–> NADH (reduced form of NAD)
NADH has absorbance at 340 nm; NAD does not.
Factors that influence enzymatic reactions - inhibitors
interfere with the reaction
Enzymes of clinical significance - Alkaline phosphatase (ALP) - location in body
almost all tissues
Enzymes of clinical significance - Alkaline phosphatase (ALP) - clinical significance - increased
liver disease
bone disease
biliary tract obstruction (higher levels than hepatocellular disorders - hepatitis, cirrhosis)
Enzymes of clinical significance - Alkaline phosphatase (ALP) - higher in what population?
children
adolescents
pregnant women
healing bone fractures
Enzymes of clinical significance - Alkaline phosphatase (ALP) - optimal pH
pH = 9-10
Enzymes of clinical significance - AST - location in body
Many tissues.
Highest in liver, heart, and skeletal muscle.
Enzymes of clinical significance - AST - clinical significance - increased
liver disease (marked increased in viral hepatitis)
acute myocardial infarction (AMI)
muscular dystrophy
Does hemolysis affect AST testing?
yes
Enzymes of clinical significance - AST - method of measurement
Pyridoxal-5-Phosphate (P5P) is added as a cofactor in chemical reaction (Method of Henry).
P5P is one of the six active forms of B6 (activated in the liver).
Enzymes of clinical significance - ALT - location in the body
Liver, RBCs
Enzymes of clinical significance - ALT - clinical significance - increased
liver disease
-marked increase in viral hepatitis
What enzyme is more specific for liver disease?
A. ALP
B. AST
C. ALT
D. GGT
C. ALT
What is the most common product in both ALT and AST chemical reactions?
glutamate
Enzymes of clinical significance - GGT - location in body
Liver, kidneys, pancreas
Enzymes of clinical significance - GGT - clinical significance - increased
all hepatobiliary disorders
chronic alcoholism
-highest levels with obstructive disorders
What enzyme is the most sensitive for all types of liver disease and is used by treatment centers to monitor abstention from alcohol?
A. ALP
B. AST
C. ALT
D. GGT
D. GGT
Enzymes of clinical significance - LD - location in body
All tissues.
Highest in liver, heart, skeletal muscle, and RBCs
Enzymes of clinical significance - LD - clinical significance - increased
acute myocardial infarction (AMI) - LD 1 & 2 elevated
liver disease - LD-5 elevated
pernicious anemia (highest levels) - LD-1 elevated
What enzyme catalyzes lactic acid to pyruvic acid?
lactate dehydrogenase (LD)
Does hemolysis affect LD testing?
yes
What temperature should LD samples be stored at?
25C (NOT 4C)
Enzymes of clinical significance - CK - location in body
cardiac muscle (CK-MB isotope)
skeletal muscle
brain
Enzymes of clinical significance - CK - clinical significance - increased
AMI
muscular dystrophy (highest levels)
What reaction does CK catalyze?
phosphocreatine + ADP <–> creatine + ADP
What enzyme is the most sensitive for skeletal muscle disease?
A. LD
B. CK
C. AMS
D. LPS
B. CK
Which factors can affect testing for CK?
A. all anticoagulants, except heparin
B. physical activity
C. intramuscular injections
D. All of the above
D. all of the above
-physical activity and IM injections can cause an increase in CK
-inhibited by all anticoagulants, except heparin
Which isotope of CK is used in the diagnosis of AMI?
CK-MB
Enzymes of clinical significance - Amylase (AMS) - location in body
salivary glands
pancreas
Enzymes of clinical significance - Amylase (AMS) - clinical significance - increased
acute pancreatitis
other abdominal diseases
mumps
Enzymes of clinical significance - Amylase (AMS) - function
breaks down starch to simple sugars
Enzymes of clinical significance - Amylase (AMS) - levels in pancreatitis
Levels increased 2-12 hours after attack, peak at 24 hours, and return to normal in 3-5 days.
Enzymes of clinical significance - Lipase (LPS) - location in body
pancreas
Enzymes of clinical significance - Lipase (LPS) - clinical significance - increased
acute pancreatitis
Enzymes of clinical significance - Lipase (LPS) - function
breaks down triglycerides into fatty acids & glycerol
Enzymes of clinical significance - Lipase (LPS) - levels in pancreatitis
Usually parallel amylase, but may stay elevated longer.
-more specific than amylase for pancreatic disease
Enzymes of clinical significance - Glucose-6-phosphate-dehydrogenase (G6PD) - location in body
RBCs
Enzymes of clinical significance - Glucose-6-phosphate-dehydrogenase (G6PD) - measurement
Measured in hemolysate of whole blood.
Enzymes of clinical significance - Glucose-6-phosphate-dehydrogenase (G6PD) - clinical significance
Inherited deficiency can lead to drug-induced hemolytic anemia.
Diagnostic enzymology - hepatocellular disorders
AST
ALT
LD
Diagnostic enzymology - biliary tract obstruction
ALP
GGT
Diagnostic enzymology - skeletal muscle disorders
CK
AST
LD
aldolase
Diagnostic enzymology - bone disorders
ALP
Diagnostic enzymology - acute pancreatitis
Amylase
Lipase
Cardiac markers for diagnosis AMI - CK-MB - elevation after chest pain
4-6 hours
Cardiac markers for diagnosis AMI - CK-MB - duration of elevation
2-3 days
Cardiac markers for diagnosis AMI - CK-MB - sensitivity/specificity
not entirely specific for AMI
Cardiac markers for diagnosis AMI - CK-MB - methods of measurment
immunoassay
Cardiac markers for diagnosis AMI - CK-MB - most often used in combination with what other cardiac marker?
troponin
Cardiac markers for diagnosis AMI - Myoglobin - elevation after chest pain
1-4 hours
Cardiac markers for diagnosis AMI - Myoglobin - duration of elevation
18-24 hours
Cardiac markers for diagnosis AMI - Myoglobin - sensitivity/specificity
sensitive but not specific at all
Cardiac markers for diagnosis AMI - Myoglobin - method of measurement
immunoassay
Cardiac markers for diagnosis AMI - Cardiac troponins (cTnI or cTnT) - elevation after chest pain
3-10 hours
Cardiac markers for diagnosis AMI - Cardiac troponins (cTnI or cTnT) - duration of elevation
4-10 days
Cardiac markers for diagnosis AMI - Cardiac troponins (cTnI or cTnT) - sensitivity/specificity
high sensitivity & specificity
Cardiac markers for diagnosis AMI - Cardiac troponins (cTnI or cTnT) - method of measurement
immunoassay
What cardiac marker is considered the definitive marker for AMI?
troponin
Testing recommendations for drawing blood for cardiac markers
Draw at admission, at 6-9 hours, & at 12-24 hours, if previous results were not increased.
Which cardiac troponin is more specific, cTnI or cTnT?
cTnI
Which cardiac troponin is more specific, cTnI or cTnT?
cTnI
List cardiac tests used to diagnose heart failure.
B-type natriuretic peptide (BNP)
Cardiac tests - BNP - clinical significance
Released from the heart muscle of the left ventricle when fluid builds from heart failure. Acts on the kidneys to increase excretion of fluid.
List the cardiac tests used to assess risk of Coronary Artery Disease (CAD).
- High-sensitivity CRP (hs-CRP)
- Total cholesterol
- HDL cholesterol
- LDL cholesterol
- Triglycerides
Tests to assess risk of CAD - High sensitivity CRP (hs-CRP) - clinical significance
Non-specific marker of inflammation.
Best single marker for predicting cardiovascular events.
Tests to assess risk of CAD - High sensitivity CRP (hs-CRP) - why should it be tested on 2 occasions?
because of individual variability
Tests to assess risk of CAD - High sensitivity CRP (hs-CRP) - methods of measurement
Nephelometry
Immunoassay
Tests to assess risk of CAD - Total cholesterol - clinical significance
Most often used in conjunction with HDL & LDL cholesterol.
Desirable: <200 mg/dL
Tests to assess risk of CAD - HDL cholesterol - clinical significance
Low level are a risk factor.
Desirable: >=60 mg/dL
Tests to assess risk of CAD - LDL cholesterol - clinical significance
Major cause of CAD.
Primary target of therapy.
Optimal: <100 mg/dL
Tests to assess risk of CAD - Triglycerides - clinical significance
Independent risk factor for CAD.
Desirable level: <150 mg/dL
Primary lipid disorders - Lipoprotein Lipase Deficiency - laboratory findings
Extremely high triglyceride levels: 5,000-10,000 mg/dL
Elevated plasma chylomicrons.
Extremely “milky”-looking serum.
Erupted xanthomas are common manifestations of disease.
Primary lipid disorders - Familial Combined Hyperlipidemia - laboratory findings
Triglycerides usually between 200-400 mg/dL.
-further classified by which lipid is elevated
Primary lipid disorders - Familial Hypertriglyceridemia - laboratory findings
-moderate increase in plasma triglycerides
-increased VLDL
-sometimes decreased HDL
-milky serum after overnight refrigeration
Primary lipid disorders - Familial Hypercholesterolemia - laboratory findings
-moderate increased in plasma LDL values (300=450 mg/dL)
-defect in the LDL receptor pathway leads to deposits of LDL in skin, tendons, and arteries.
Primary lipid disorders - Tangier Disease (Hypoalphalipoproteinemia) - laboratory findings
-decreased or absent plasma HDL
-orange-colored tonsils often present
Primary lipid disorders - Tangier Disease (Hypoalphalipoproteinemia) - pathophysiology
Primary lipid disorders - Lipoprotein Lipase Deficiency - pathophysiology
ApoC-2 or LPL deficiency
Primary lipid disorders - Familial Hypercholesterolemia - pathophysiology
LDL receptor deficiency
Primary lipid disorders - Familial Hypertriglyceridemia - pathophysiology
VLDL overproduction
Primary lipid disorders - Familial Combined Hyperlipidemia - pathophysiology
VLDL overproduction
Bilirubin metabolism
Total bilirbuin - reference range
0.2-1 mg/dL
Total bilirubin - clinical significance - increased
liver disease
hemolysis
HDN
-in infants, >20 mg/dL is associated with brain damage (kernicterus)
What is total bilirubin the sum of?
the sum of conjugated, unconjugated, & delta bilirubin
What consideration should be taken when collecting a specimen for bilirubin testing?
Avoid hemolysis.
Protect from sunlight.
Total bilirubin - method of measurement
Jendrassik-Grof method
-diazo reagent
-accelerator added so unconjugated bilirbuin reacts.
Total bilirubin - method of measurement (neonates)
Bilirubinometry - measures reflected light from skin using 2 wavelengths.
Conjugated bilirubin (direct bilirubin) - reference range
<0.8 mg/dL
Conjugated bilirubin (direct bilirubin) - clinical significance - increased
liver disease
obstructive jaundice
Conjugated bilirubin (direct bilirubin) - composed of?
bilirubin monoglucuronide
bilirubin diglucuronide & delta bilirubin (bound to albumin; only seen with significant hepatic obstruction)
Conjugated bilirubin (direct bilirubin) - method of measurement
Jendrassik-Grof method
-diazo reagent
-NO accelerator required
Unconjugated bilirubin (indirect bilirubin) - reference range
<0.2 mg/dL
Unconjugated bilirubin (indirect bilirubin) - clinical significance - increased
prehepatic, posthepatic, & some types of hepatic jaundice
Unconjugated bilirubin (indirect bilirubin) - method of measurement
Calculated value.
Total bili - direct bili = unconjugated bili
Unconjugated vs. Conjugated bilirubin - bound to protein
Unconjugated - yes (albumin)
Conjugated - no (except delta bili)
Unconjugated vs. Conjugated bilirubin - type of compound
Unconjugated - nonpolar
Conjugated - polar
Unconjugated vs. Conjugated bilirubin - soluble in water?
Unconjugated - no
Conjugated - yes
Unconjugated vs. Conjugated bilirubin - present in urine?
Unconjugated - no
Conjugated - yes
Unconjugated vs. Conjugated bilirubin - reaction with diazotized sulfanilic acid
Unconjugated - indirect (only reacts in the presence of accelerator)
Conjugated - direct (reacts without accelerator)
Unconjugated vs. Conjugated bilirubin - affinity for brain tissue (causes kernicterus)
Unconjugated - high
Conjugated - Low
Differential Diagnosis of Jaundice - prehepatic jaundice
Total bili - increased
Direct bili - normal
Urine bilirubin - negative
Urine urobilinogen - increased
Differential Diagnosis of Jaundice - hepatic jaundice
Total bilirubin - increased
Direct bili - variable
Urine bilirubin - variable
Urine urobilinogen - decreased
Differential Diagnosis of Jaundice - post-hepatic jaundice
Total bilirubin - increased
Direct bilirubin - increased
Urine bilirubin - positive
Urine urobilinogen - decreased
List the anterior pituitary hormones.
- ACTH
- FSH
- GH
- LH
- Prolactin (PRL)
- TSH
List the posterior pituitary hormones.
- ADH
- Oxytocin
Anterior pituitary hormone - ACTH - regulates?
production of adrenocortical hormones by the adrenal cortex
-cortisol
-androgens (progesterone, estrogen)
-aldosterone
Anterior pituitary hormone - ACTH - regulated by?
corticotropin-releasing hormone (CRH) from the hypothalamus
Anterior pituitary hormone - ACTH - diurnal variation
highest levels in early a.m., lowest in the afternoon
Anterior pituitary hormone - ACTH - clinical significance
increased in Cushing’s disease
Anterior pituitary hormone - ACTH - collection
Collect on ice. Store frozen.
Anterior pituitary hormone - FSH - regulates?
sperm & egg production
Anterior pituitary hormone - FSH - regulated by?
gonadotropin-releasing hormone (GHRH) from the hypothalamus
Anterior pituitary hormone - FSH - clinical significance
Sharp increase just before ovulation.
Anterior pituitary hormone - Growth hormone (GH) - regulates?
-Protein synthesis
-Cell growth & division
Anterior pituitary hormone - Growth hormone (GH) - regulated by?
growth-hormone releasing hormone (GHRH) & somatostatin from the hypothalamus.
Anterior pituitary hormone - Growth hormone (GH) - clinical significance
Increased - gigantism, acromegaly
Decreased - dwarfism
Anterior pituitary hormone - Growth hormone (GH) - clinical significance
Increased - gigantism, acromegaly
Decreased - dwarfism
Anterior pituitary hormone - Luteinizing hormone (LH) - regulates?
-Maturation of follicles
-Ovulation
-Production of estrogen, progesterone, testosterone
Anterior pituitary hormone - Luteinizing hormone (LH) - regulated by?
gonadotropin-releasing hormone (GnRH) from the hypothalamus
Anterior pituitary hormone - Luteinizing hormone (LH) - clinical significance
Sharp increase just before ovulation
Anterior pituitary hormone - Luteinizing hormone (LH) - home tests
ELISA kits to detect ovulation
Anterior pituitary hormone - Prolactin (PRL) - regulates?
lactation
Anterior pituitary hormone - Prolactin (PRL) - regulated by?
prolactin-releasing hormone (PRF) & prolactin-inhibiting factor (PIF) from the hypothalamus
Anterior pituitary hormone - TSH - regulates?
production of T3 & T4 by the thyroid
Anterior pituitary hormone - TSH - regulated by?
thyrotropin-releasing hormone (TRH) from the hypothalamus
Anterior pituitary hormone - TSH - clinical significance
Increased - hypothyroidism
Decreased - hyperthyroidism
Posterior pituitary - ADH - regulates?
Reabsorption of water in distal renal tubules
Posterior pituitary - ADH - where is it produced?
hypothalamus
Posterior pituitary - ADH - where is it stored?
posterior pituitary
Posterior pituitary - ADH - what is it’s release stimulated by?
-increased osmolality
-decreased blood volume
-decreased blood pressure
Posterior pituitary - ADH - clinical significance
decreased in diabetes insipidus
Posterior pituitary - Oxytocin - regulates?
-uterine contractions during childbirth
-lactation
Posterior pituitary - Oxytocin - where is it produced?
hypothalamus
Posterior pituitary - Oxytocin - where is it stored?
posterior pituitary
Thyroid hormones - Thyroxine (T4) - regulates?
-metabolism
-growth
-development
Which thyroid hormone is considered the principle thyroid hormone?
T4
Thyroid hormones - Thyroxine (T4) - contains how many atom of iodine?
4
Thyroid hormones - Thyroxine (T4) - regulated by?
TSH
Thyroid hormones - Thyroxine (T4) - most bound to?
thyroxine-binding globulin (TBG)
Thyroid hormones - Thyroxine (T4) - clinical significance
Increased - hyperthyroidism
Decreased - hypothyroidism
Thyroid hormones - Triiodothyronine (T3) - regulates?
-metabolism
-growth
-development
Thyroid hormones - Triiodothyronine (T3) - how is most formed?
from deiodination of T4 by the tissues.
Thyroid hormones - Triiodothyronine (T3) - contains how many atoms of iodine?
3
Thyroid hormones - Triiodothyronine (T3) - regulated by?
TSH
Thyroid hormones - Triiodothyronine (T3) - clinical significance
Increased - hyperthyroidism
Decreased - hypothyroidism
True or False. T3 is 4x-5x more potent than T4.
True
Thyroid hormones - Calcitonin - regulates?
inhibition of calcium resorption
Thyroid hormones - Calcitonin - clinical significance
important in diagnosis of thyroid cancer
Thyroid hormones - Calcitonin - clinical significance
important in diagnosis of thyroid cancer
Parathyroid hormone (PTH) - regulates?
calcium & phosphate
Parathyroid hormone (PTH) - primary hyperparathyroidism - laboratory findings
Increased PTH
Increased calcium
Decreased phosphate
Parathyroid hormone (PTH) - Hypoparathyroidism - laboratory findings
Decreased PTH
Decreased calcium
Increased phosphate
Parathyroid hormone (PTH) - primary hypoparathyroidism
Thyroid function testing - Primary hypothyroidism - laboratory findings
Increased TSH
Decreased Free T4 (FT4)
Decreased Free T3 (FT3)
Thyroid function testing - Secondary hypothyroidism - laboratory findings
Decreased or normal TSH
Decreased Free T4
Decreased Free T3
Thyroid function testing - Hyperthyroidism - laboratory findings
Decreased TSH
Increased Free T4
Increased Free T3
Thyroid function testing - T3 Thyrotoxicosis - laboratory findings
Decreased TSH
Normal Free T4
Increased Free T3
Thyroid function testing - Primary vs. Secondary Hypothyroidism
List the adrenal hormones located in the adrenal cortex.
- aldosterone
- cortisol
List the adrenal hormones located in the adrenal medulla.
- epinephrine
- norepinephrine
(adrenaline, noradrenaline)
Adrenal hormones - cortex - Aldosterone - regulates?
reabsorption of sodium in the renal tubules
Adrenal hormones - cortex - Aldosterone - clinical significance
Increased - causes hypertension due to water & sodium retention
Decreased - leads to severe water & electrolyte abnormalities
Adrenal hormones - cortex - Cortisol - regulates?
-carbohydrate, fat, & protein metabolism
-water & electrolyte balance
-suppresses inflammatory & allergic reactions
Adrenal hormones - cortex - Cortisol - regulated by?
ACTH
Adrenal hormones - cortex - Cortisol - diurnal variation
Highest in a.m.
Adrenal hormones - cortex - Cortisol - Cushing syndrome
Increased cortisol
Loss of diurnal variation
Adrenal hormones - cortex - Cortisol - Addison disease
Decreased cortisol
Adrenal hormones - medulla - Epinephrine, norepinephrine - regulates?
“Fight or flight syndrome.”
Stimulation of the sympathetic nervous system.
What is the primary hormone of the adrenal medulla?
epinephrine
Adrenal hormones - medulla - catecholamines
Epinephrine & norepinephrine
Adrenal hormones - medulla - epinephrine & norepinephrine - metabolites
metanephrines => vanilylmandelic acid (VMA)
Adrenal hormones - medulla - epinephrine & norepinephrine - clinical significance
Increased with pheochromocytoma (rare catecholamine producing tumor)
Adrenal hormones - medulla - epinephrine & norepinephrine - tests
plasma & urine catecholamines & metanephrines
urine VMA
Reproductive hormones - ovaries - estrogens - regulates?
-development of female reproductive organs & secondary sex characteristics
-regulation of the menstrual cycle
-maintenance of pregnancy
What is the major estrogen produced by the ovaries (and most potent)?
Estradiol (E2)
(also produced in the adrenal cortex)
Reproductive hormones - ovaries - progesterone - regulates?
preparation of uterus for ovum implantation and maintenance of pregnancy
Reproductive hormones - ovaries - progesterone - also produced by?
the placenta
Reproductive hormones - ovaries - progesterone - metabolite
pregnanediol
Reproductive hormones - ovaries - progesterone - clinical significance
useful in infertility studies & to assess placental function
Reproductive hormones - placenta - estrogen (estriol) - regulates?
no hormonal activity
Reproductive hormones - placenta - estrogen (estriol) - clinical significance
used along with AFP, hCG, and inhibin A as part of the Quadrapole (Quad) screen to monitor fetal growth and development
Reproductive hormones - placenta - progesterone - regulates?
maintenance of pregnancy
Reproductive hormones - placenta - human chorionic gonadotropin (hCG) - regulates?
-progesterone production by the corpus luteum during early pregnancy
-development of fetal gonads
Reproductive hormones - placenta - human chorionic gonadotropin (hCG) - clinical significance
-pregnancy
-gestational trophoblastic disease (e.g., hydatidiform mole)
-testicular tumor
-other hCG-producing tumors
Reproductive hormones - placenta - inhibin A - regulates?
hormone made by the placenta - inhibits secretion of FSH by anterior pituitary
Reproductive hormones - placenta - inhibin A - clinical significance
part of Quad screen - monitor fetal growth and development
-high levels seen with Down syndrome
Reproductive hormones - testes - testosterone - regulates?
development of male reproductive organs & secondary sex characteristics
Reproductive hormones - testes - testosterone - metabolites
-estradiol
-dihydrotestosterone (DHT)
Pancreatic hormones - insulin - regulates?
carbohydrate metabolism
Pancreatic hormones - insulin - where is it produced?
produced in the beta cells of the islets of Langerhans
Pancreatic hormones - insulin - functions?
decreases plasma glucose levels by increasing movement of glucose into the cells for metabolism
Pancreatic hormones - insulin - clinical significance
Decreased in diabetes mellitus.
Increased with insulinoma and hypoglycemia.
Pancreatic hormones - glucagon - regulates?
glycogenolysis
gluconeogenesis
lipolysis
Pancreatic hormones - glucagon - where is it produced?
produced in the alpha cells of the islets of Langerhans
Pancreatic hormones - glucagon - function
increases plasma glucose levels
Endocrine disorders - Addison Disease - laboratory findings
-decreased cortisol
-decreased aldosterone
-increased ACTH
-decreased sodium
-increased potassium
Endocrine disorders - Addison Disease - endocrine gland affected
adrenal cortex
Endocrine disorders - Addison Disease - diagnosis
-SCREEN for primary adrenal insufficiency with morning plasma cortisol
-CONFIRMATION: decreased response to cosyntropin stimulation
Endocrine disorders - Addison Disease - common symptoms
-low blood pressure
-darkening of the skin
Endocrine disorders - Cushing Disease - laboratory findings
-increased cortisol
-increased ACTH
Endocrine disorders - Cushing Disease - endocrine gland affected
tumor of the pituitary gland
Endocrine disorders - Cushing Disease - diagnosis
CONFIRM: overnight dexamethasone suppression test
Endocrine disorders - Acromegaly - laboratory findings
increased growth hormone
Endocrine disorders - Acromegaly - endocrine gland affected
pituitary gland
Endocrine disorders - Acromegaly - diagnosis
CONFIRM: oral glucose tolerance test - growth hormone will remain abnormally elevated
Endocrine disorders - Diabetes insipidus - laboratory findings
-elevated plasma sodium
-elevated plasma osmolality
-decreased urine osmolality
Endocrine disorders - Diabetes insipidus - endocrine gland affected
hypothalamus OR kidneys
Endocrine disorders - Diabetes insipidus - pathophysiology
Deficient production or action of ACTH
Endocrine disorders - Diabetes insipidus - symptoms
polyuria
polydipsia
Endocrine disorders - Pheochromocytoma - laboratory findings
-elevated plasma AND catecholamines (epinephrine & norepinephrine)
-elevated plasma AND metanephrines
-elevated urine VMA
Endocrine disorders - Pheochromocytoma - common symptoms
-unexplained high blood pressure
-headaches
-sweating
Endocrine disorders - Hyperprolactinemia - laboratory findings
elevated plasma prolactin
Endocrine disorders - Hyperprolactinemia - endocrine gland affected
pituitary gland
Endocrine disorders - Pheochromocytoma - endocrine gland affected
adrenal medulla
Endocrine disorders - Hyperprolactinemia - hook effect
falsely decreased results, immunoassay
Endocrine disorders - Hyperprolactinemia - falsely elevated results
macroprolactin
lowest concentration of drug in blood that will produce desired effect
minimum effective concentration (MEC)
lowest concentration of drug in blood that will produce an adverse response
minimum toxic concentration (MTC)
ratio of MTC to MEC
therapeutic index
lowest concentration of drug measured in blood; reached just before the next scheduled dose; shouldn’t fall below MEC
trough
highest concentration of drug measured in blood; drawn immediately on achievement of steady state; should not exceed MTC
peak
amount of drug absorbed & distributed = amount of drug metabolized & excreted; usually reached after 5-7 half lives
steady state
the time required for the concentration of a drug to be decreased by half
half-life
the rates of absorption, distribution, biotransformation, & excretion
pharmacokinetics
Therapeutic drug groups - salicylates, acetaminophen
analgesics
Therapeutic drug groups - phenobarbital
antiepileptics
Therapeutic drug groups - phenytoin
antiepileptics
Therapeutic drug groups - valproic acid
antiepileptics
Therapeutic drug groups - carbamazepine
antiepileptics
Therapeutic drug groups - ethosuximide
antiepileptics
Therapeutic drug groups - felbamate
antiepileptics
Therapeutic drug groups - gabapentin
antiepileptics
Therapeutic drug groups - lamotrigine
antiepileptics
Therapeutic drug groups - methotrexate
antineoplastics
Therapeutic drug groups - aminoglycosides (amikacin, gentamicin, kanmycin, tobramycin), vancomycin
antibiotics
Therapeutic drug groups - digoxin
cardioactives
Therapeutic drug groups - disopyramide
cardioactives
Therapeutic drug groups - procainamide
cardioactives
Therapeutic drug groups - quinidine
cardioactives
Therapeutic drug groups - tricyclic antidepressants
psychoactives
Therapeutic drug groups - lithium
psychoactives
Therapeutic drug groups - cyclosporine
immunosuppressants
Therapeutic drug groups - tacrolimus (FK-506)
immunosuppressants
Toxic agents - ethanol - analytic method
-gas chromatography
-enzymatic methods
Toxic agents - carbon monoxide - analytic method
-differential spectrophotometry (cooximeter)
-gas chromatography
Toxic agents - arsenic - analytic method
atomic absorption
Toxic agents - lead - analytic method
atomic absorption
Toxic agents - pesticides - analytic method
measurement of serum pseudocholinesterase
Toxic agents - methanol - analytic method
gas chromatography
Drugs of abuse urine screen - drugs routinely tested
- amphetamines
- barbiturates
- benzodiazepines
- cannabinoids
- cocaine
- methadone
- opiates
- phencyclidine (PCP)
- tricyclic antidepressants
Drugs of abuse urine screen - adulterated urine
value outside physiological range or presence of a substance that isn’t found in human urine
-pH <3 or >=11
-nitrite >=500 mg/dL
-presence of chromium, halogens (bleach, iodine, fluoride), glutaraldehyde, pyridine, or surfactant
Drugs of abuse urine screen - substituted urine
values that aren’t consistent with normal human urine
-creatine <2 mg/dL
-specific gravity <=1.0010 or >=1.0200
Drugs of abuse urine screen - diluted urine
creatine and specific gravity lower than expected for normal human urine
-creatine >=2 mg/dL but <=20mg/dL
-specific gravity >=1.0010 but <=1.0030
Drugs of abuse urine screen - method of measurement
immunoassay
Drugs of abuse urine screen - confirmation
mass spectrometry
Common tumor markers - alpha-Fetoprotein (AFP) - type of cancer for which marker is most often diagnosed
Liver
Common tumor markers - alpha-Fetoprotein (AFP) - clinical use
-aid diagnosis
-monitor therapy
-detect recurrence
Common tumor markers - alpha-Fetoprotein (AFP) - produced by?
fetal liver
Common tumor markers - alpha-Fetoprotein (AFP) - clinical significance
increased:
-certain tumors
-hepatitis
-pregnancy
Common tumor markers - CA 15-3 and CA 27.29 - type of cancer for which marker is most often used
breast
Common tumor markers - CA 15-3 and CA 27.29 - clinical use
-stage disease
-monitor therapy
-detect recurrence
Common tumor markers - CA 15-3 and CA 27.29 - clinical significance
-breast cancer
-can be increased with other cancers & non-cancerous conditions
Common tumor markers - CA 19-9 - type of cancer for which marker is most often used
pancreatic
Common tumor markers - CA 19-9 - clinical use
-stage disease
-monitor therapy
-detect recurrence
Common tumor markers - CA 19-9 - clinical significance
-pancreatic cancer
-can be increased with other cancers & non-cancerous conditions
Common tumor markers - CA 125 - type of cancer for which marker is most often used
ovarian
Common tumor markers - CA 125 - clinical use
-aid diagnosis
-monitor therapy
-detect recurrence
Common tumor markers - CA 125 - clinical significance
-ovarian cancer
-can be increased with other cancers & gynecological conditions
Common tumor markers - carcinoembryonic antigen (CEA) - type of cancer for which marker is most often used
colorectal
Common tumor markers - carcinoembryonic antigen (CEA) - type of antigen
fetal antigen re-expressed in tumors
Common tumor markers - carcinoembryonic antigen (CEA) - clinical use
-monitor therapy
-detect recurrence
Common tumor markers - carcinoembryonic antigen (CEA) - clinical significance
-colorectal cancer
-can be increased with other cancers, non-cancerous conditions, & in smokers
Common tumor markers - hCG - type of cancer for which marker is most often used
-ovarian & testicular cancers
-gestational trophoblastic diseases
Common tumor markers - hCG - clinical use
-aid diagnosis
-monitor therapy
-detect recurrence
Common tumor markers - hCG - clinical significance
-ovarian cancer
-testicular cancer
-gestational trophoblastic diseases
-pregancy
Common tumor markers - Prostate-specific antigen (PSA) - type of cancer for which marker is most often used
prostate
Common tumor markers - Prostate-specific antigen (PSA) - clinical use
-screening
-aid diagnosis
-monitor therapy
-detect recurrence
Which tumor marker is the most widely used?
PSA
Common tumor markers - Prostate-specific antigen (PSA) - screening asymptomatic men is controversial
-some men with prostate cancer don’t have increased PSA
-PSA can be increased in other conditions
Common tumor markers - Prostate-specific antigen (PSA) - free PSA
may be helpful when PSA is borderline
Common tumor markers - Prostate-specific antigen (PSA) - free PSA
may be helpful when PSA is borderline
Common tumor markers - Thyroglobulin - type of cancer for which marker is most often used
thyroid
Common tumor markers - Thyroglobulin - clinical use
-monitor therapy
-detect recurrence
Common tumor markers - Thyroglobulin - clinical significance
-thyroid cancer
-increased in other thyroid diseases
Common tumor markers - Thyroglobulin - what should be measured at the same time?
antithyroglobulin antibodies
-Log[H+] or log 1/[H+]
pH
a chemical that can yield H+; proton donor; pH <7
acid
a chemical that can accept H+ or yield OH-; pH >7
base
a weak acid & its salt or conjugate base; minimizes changes in pH
buffer
What buffer is the most important one for maintaining blood pH?
A. phosphates
B. bicarbonate/carbonic acid
C. proteins
D. hemoglobin
B. bicarbonate/carbonic acid
H+ + HCO3- <==> H2CO3 <==> H20 + CO2
HCO3-; second largest fraction of anions; proton acceptor or base; equal to total CO2 - 1
bicarbonate
What is bicarbonate (HCO3-) regulated by?
kidneys
H2CO3; proton donor or weak acid; equal to PCO2 x 0.03
carbonic acid
What is carbonic acid (H2CO3) regulated by?
lungs
all forms of CO2
total CO2
(HCO3- + H2CO3 + dissolved CO2)
partial pressure of CO2
PCO2
What is PCO2 directly related to?
the amount of dissolved CO2
Henderson-Hasselbalch equation
pH = 6.1 + log ([HCO3-]/[H2CO3])
OR
6.1 + log (HCO3-/PCO2) x 0.03
Acidosis (acidemia) - laboratory findings
-blood pH <7.38
-decreased HCO3-:H2CO3 ratio (normal is 20:1)
Acidosis (acidemia) - causes
- decreased HCO3- (metabolic acidosis)
- increased H2CO3 (respiratory acidosis)
Alkalosis (alkalemia) - laboratory findings
-blood pH >7.42
-increased HCO3-:H2CO3 ratio (normal 20:1)
Alkalosis (alkalemia) - causes
- increased HCO3- (metabolic alkalosis)
- decreased H2CO3 (respiratory alkalosis)
What is compensated acidosis or alkalosis?
when compensatory mechanisms have succeeded in returning the 20:1 ratio & pH returns to normal.
-kidneys compensate for respiratory problems
-lungs compensate for metabolic problems
Acid-Base imbalances - Respiratory acidosis
pH - decreased
PCO2 - increased
HCO3- - normal
Compensation: kidneys retain HCO3-, excrete H+
Acid-Base imbalances - Metabolic acidosis
pH - decreased
PCO2 - normal
HCO3- - decreased
Compensation: hyperventilation (blow off CO2)
Acid-Base imbalances - Respiratory alkalosis
pH - increased
PCO2 - decreased
HCO3- - normal
Compensation: kidneys excrete HCO3-, retain H+
Acid-Base imbalances - Metabolic alkalosis
pH - increased
PCO2 - normal
HCO3- - increased
Compensation: hypoventilation (retain CO2)
low O2 content in arterial blood
hypoxemia
lack of O2 at cellular level
hypoxia
barometric pressure x % gas concentration
partial pressure
partial pressure of CO2 expressed in mm of Hg
PCO2
-directly related to the amount of dissolved CO2
-measure of the respiratory component (inversely proportional to respiration)
partial pressure of O2
PO2
-assesses pulmonary function
graph showing relationship between oxygen saturation & PO2
oxygen dissociation curve
provides information about hemoglobin’s affinity for O2
oxygen dissociation curve
phosphate compound in RBCs that affects O2 dissociation curve
2,3-Diphosphoglycerate (2,3-DPG)
low levels of 2,3-Diphosphoglycerate (2,3-DPG)
inhibit release of O2 to tissues
amount of O2 that is combined with hemoglobin, expressed as % of amount of O2 that can be combined with hemoglobin
oxygen saturation
1 g of hemoglobin can combine with 1.34 mL of O2
partial pressure of O2 at which hemoglobin saturation is 50%
P50
low value of P50
increased O2 affinity
(shift to the left in O2 dissociation curve)
high value of P50
decreased O2 affinity
(shift to the right in O2 dissociation curve)
Blood Gas Parameters - pH - measurement of?
[H+]
Blood Gas Parameters - pH - derivation
pH electrode on blood gas analyzer
Blood Gas Parameters - pH - reference range
7.35-7.45
Blood Gas Parameters - PCO2 - measurement of?
partial pressue of CO2
Blood Gas Parameters - PCO2 - derivation
PCO2 electrode on blood gas analyzer
Blood Gas Parameters - PCO2 - reference range
35-45 mm Hg
Blood Gas Parameters - PO2 - measurement of?
partial pressure of O2
Blood Gas Parameters - PO2 - derivation
PO2 electrode on blood gas analyzer
Blood Gas Parameters - PO2 - reference range
80-100 mm Hg
Blood Gas Parameters - HCO3- - measurement of?
bicarbonate
Blood Gas Parameters - HCO3- - derivation
calculated value on blood gas analyzer
Blood Gas Parameters - HCO3- - reference range
22-26 mmol/L
Blood Gas Parameters - total CO2 - measurement of?
bicarbonate + carbonic acid
Blood Gas Parameters - total CO2 - derivation
calculated value on blood gas analyzer
Blood Gas Parameters - total CO2 - reference range
23-27 mmol/L
Blood Gas Parameters - base excess - measurement of?
-metabolic component of acid-base status
-difference between titratable bicarbonate of sample & that of normal blood sample
Blood Gas Parameters - base excess - derivation
calculated value on blood gas analyzer
Blood Gas Parameters - base excess - reference range
-2 to +2 mEq/L
*negative values indicate base deficit
Blood Gas Parameters - oxygen saturation - measurement of
amount of oxygenated hemoglobin
Blood Gas Parameters - oxygen saturation - derivation
measured by oximeter
Blood Gas Parameters - oxygen saturation - reference range
94% - 100%
Blood Gas Instrumentation - pH electrode - description
H+-sensitive glass electrode containing Ag/AgCl wire in electrolyte of known pH & reference (calomel) electrode (Hg/Hg2Cl2)
-measurement is potentiometric (change in voltage indicates activity of analyte)
Blood Gas Instrumentation - pH electrode - measures?
[H+]
Blood Gas Instrumentation - pH electrode - calibration
2 phosphate buffers of known pH
-store at RT
-don’t expose to air
Blood Gas Instrumentation - PCO2 electrode - description
pH electrode covered with membrane permeable to CO2, with bicarbonate buffer between membrane & electrode
-measure is potentiometric - change in voltage indicates activity of analyte
Blood Gas Instrumentation - PCO2 electrode - measures?
dissolved CO2
Blood Gas Instrumentation - PCO2 electrode - calibration
2 gases of known PCO2
Blood Gas Instrumentation - PO2 electrode (Clark electrode) - measures?
dissolved O2
Blood Gas Instrumentation - PO2 electrode - calibration
2 gases of known PO2
Blood Gas Instrumentation - PO2 - description
Platinum cathode & Ag/AgCl anode covered with semipermeable membrane.
-measurement is amperometric - amount of current flow is indication of O2 present
Blood Gas Instrumentation - Co-oximeter - description
-spectrophotometer that reads absorbance or resistance at isobestic point (wavelength where reduced & oxyhemoglobin have same absorbance or reflectance, e.g., 805 nm)
AND
-differential point (wavelength where reduced & oxyhemoglobin have different absorbance or reflectance, e.g., 650 nm)
Blood Gas Instrumentation - Co-oximeter - measures?
oxygen saturation
-some also measure carboxyhemoglobin, methemoglobin, & sulfhemoglobin by using additional wavelengths
Blood Gas Instrumentation - Co-oximeter - calibration
calibration curve prepared from specimens with 0% & 100% oxygen saturation
Sources of error in arterial blood gases - hyperventilation - effect
-decreased PCO2
-increased pH
-increased PO2
Sources of error in arterial blood gases - specimen exposed to air - effect
-decreased PCO2
-increased pH
-increased PO2
Sources of error in arterial blood gases - specimen at RT >30 minutes - effect
-increased PCO2
-decreased pH
-decreased PO2
Albumin/Globulin (AG) ratio - calculation
Albumin/Globulin (AG) ratio - normal range
1-2.5
Albumin/Globulin (AG) ratio - clinical significance
reversed A/G ratio with multiple myeloma, liver disease
Amylase:creatinine clearance ratio - calculation
Amylase:creatinine clearance ratio - normal range
2%-5%
Amylase:creatinine clearance ratio - clinical significance
increased - acute pancreatitis
decreased - macroamylasemia
Anion gap - calculation
Anion gap - normal range
7-16
Anion gap - normal range
10-20
difference between unmeasured anions and unmeasured cations
anion gap
Anion gap - clinical significance - increased
-renal failure
-diabetic acidosis
-lactic acidosis
-methanol, ethanol, ethylene glycol, or salicylate poisoning
-laboratory error
Anion gap - all determinations are increased or decreased
possible instrument error in 1 of the determinations
True or False. Anion gap cannot be a negative number.
True
BUN-to-creatinine ratio - calculation
BUN-to-creatinine ratio - normal range
10-20
BUN-to-creatinine ratio - clinical significance - renal disease
normal ratio
BUN-to-creatinine ratio - clinical significance - pre-renal conditions
increased ratio with increased BUN & normal creatinine
BUN-to-creatinine ratio - clinical significance - post-renal conditions
increased ratio with increased creatinine
BUN-to-creatinine ratio - clinical significance - decreased ratio
decreased ratio with decreased urea production
(e.g., severe liver disease, decreased protein intake)
Creatinine clearance - calculation
Creatinine clearance - normal range
Males: 97-137 mL/min
Females: 88-128 mL/min
Creatinine clearance - clinical significance
decreased in renal disease (early indicator)
Indirect (unconjugated) bilirubin - calculation
Indirect (unconjugated) bilirubin - normal range
<0.2 mg/dL
Indirect (unconjugated) bilirubin - clinical significance
increased in pre-hepatic, post-hepatic, & some type of hepatic jaundice
LDL cholesterol - calculation
Friedewald formula
LDL cholesterol - normal range
Desirable level: <130 mg/dL
LDL cholesterol - clinical significance
Increased LDL cholesterol is associated with increased with of CAD.
LDL cholesterol - when are LDL levels not valid?
if triglycerides are >400 mg/dL
Calculated osmolality - calculation
Calculated osmolality - normal range
275-295 Osm/kg
What does osmolality measure?
concentration of solute
What contributes the most to osmolality?
electrolytes
Osmolality - clinical significance
Increased - dehydration, uremia, uncontrolled diabetes, alcohol or salicylate poisoning, excessive electrolyte IVs
Decreased - excessive water intake
Osmolal gap - calculation
Osmolal gap - normal range
0-10 mOsm/kg
similar to anion gap but based on osmotically active solute concentration rather than the concentrations of ions
osmolal gap
Osmolal gap - clinical significance
> 10 indicates abnormal concentration of unmeasured substance (e.g., isopropanol, methanol, acetone, ethylene glycol)
-used to diagnose poisonings
Urine-to-serum osmolality - calculation
Urine osmolality/serum osmolality
Urine-to-serum osmolality - normal range
1-3
Urine-to-serum osmolality - clinical significance
decreased in renal tubular deficiency and diabetes insipidus
Beer’s Law
A manual glucose assay gave the following results: Absorbance of 100 mg/dL standard = 0.3.
Absorbance of patient = 0.4.
What is the glucose concentration of the patient?
133 mg/dL
Note: If a dilution is run, multiply the answer by the reciprocal of the dilution.
mg/dl to mEq/L - calculation
A calcium is reported as 10 mg/dL. What is the concentration in mEq/L?
(Atomic weight of calcium = 40. Valence of calcium = 2+.)
5
mg/dL to mmol/L - calculation
A calcium is reported as 10 mg/dL. What is the concentration in mmol/L?
(Atomic weight of calcium = 40. Valence of calcium is 2+.)
2.5
mEq/L to mmol/L - calculation
A calcium is reported as 5 mEq/L. What is the concentration in mmol/L?
(Atomic weight of calcium = 40. Valence of calcium = 2+.)
2.5
Molarity (M) calculation
What is the molarity of a solution that contains 45 grams of NaCl per liter?
(Atomic weights: Na = 23, Cl = 35.5)
0.77
Normality (N) calculation
What is the normality of a solution that contains 98 grams of H2SO4 per 500 mL?
(Atomic weights: H = 1, S = 32, O = 16.)
4
% concentration formula
What is the concentration in % of a solution that contains 8.5 grams of NaCl per liter?
0.85%
Calculation for finding normality when given the molarity
What is the normality of a 3 M H2SO4 solution?
6
Solution Dilution calculation
How many mL of 95% alcohol are needed to prepare 100 mL of 70% alcohol?
73.7 mL
Which of the following pairs of fasting plasma glucose values demonstrates unequivocal hyperglycemia that can be used toward the diagnosis of diabetes mellitus?
A. 160 mg/dL on two separate occasions
B. 100 mg/dL and 125 mg/dL
C. 75 mg/dL on two separate occasions
D. 93 mg/dL and 195 mg/dL
A. 160 mg/dL on two separate occasions
Which photometric method is used primarily to measure antibody-antigen reactions?
A. Chemiluminescence
B. Turbidimetry
C. Nephelometry
D. Flow cytometry
C. Nephelometry
Regarding serum protein electrophoresis, which condition is associated with a beta-gamma bridge pattern?
A. Liver cirrhosis
B. Nephrotic syndrome
C. Acute inflammation
D. Monoclonal gammopathy
A. Liver cirrhosis
Which serum enzyme is elevated in all hepatobiliary disorders?
A. Gamma-glutamyl transferase
B. AST
C. Creatinine kinase
D. Amylase
A. Gamma-glutamyl transferase
The Friedewald formula can be used to indirectly determine the concentration of which of the following analytes?
A. Triglycerides
B. Phospholipids
C. LDL cholesterol
D. Lipase
C. LDL cholesterol
Which set of laboratory values corresponds to secondary hypothyroidism?
A. Increased TSH, decreased free T4, decreased free T3
B. Decreased TSH, decreased free T4, decreased free T3
C. Increased TSH, normal free T4, increased free T3
D. Decreased TSH, increased free T4, increased free T3
B. Decreased TSH, decreased free T4, decreased free T3
For which of the following clinical chemistry analytes is it important to avoid hemolysis?
A. Potassium
B. Bilirubin
C. AST
D. All of the above are susceptible to hemolysis
D. All of the above are susceptible to hemolysis
Aldosterone regulates the levels of which of the following electrolytes?
A. Sodium
B. Magnesium
C. Calcium
D. Bicarbonate
A. Sodium
Laboratory findings for which of the following endocrine disorders include decreased morning plasma and/or salivary cortisol, decreased ACTH, and decreased sodium?
A. Cushing disease
B. Diabetes insipidus
C. Addison disease
D. Acromegaly
C. Addison disease
A specimen for blood gas analysis that is left at room temperature for more than 30 minutes would be expected to show which set of changes?
A. Decreased PCO2, increased pH, increased PO2
B. Increased PCO2, decreased pH, decreased PO2
C. Decreased PCO2, decreased pH, decreased PO2
D. Increased PCO2, increased pH, increased PO2
B. Increased PCO2, decreased pH, decreased PO2
Acid Base Balance: Mnemonic (ROME)
Respiratory Acidosis
Respiratory Alkalosis
Metabolic Acidosis
Metabolic Alkalosis