Blakes Clinical Chemistry lab Study questions Flashcards
Gold standard of glucose methodology
hexokinase method
- due to its higher specificity
- its a coupled enzyme assay uses hexokinase enzyme to convert NADP to NADPH
Hexokinase method reaction
1.) glucose + ATP by enzyme hexose kinase —> glucose-6-phosphate + ADP
2.) glucose-6-phosphate (enzyme G-6-PD)—> 6-phosphogluconate (NADP—>NADPH)
Glucose can be measured in the
Blood, serum, plasma, urine, and body fluids
When glucose is measured in whole blood the values are
10-12% less then serum
Glucose testing
separate cells from
5-7% what
serum and or plasma within 1 hour to prevent the loss of glucose through glycolysis ( decreases 5-7%/hour)
Glucose testing
acceptable draw tubes
Red, gold, and green, and gray
Glucose oxidase method
coupled enzyme assay using the glucose oxidase enzyme
this is cheaper then 2 methodologies
Glucose oxidase reaction
Glucose reacts with water and Oxygen with glucose oxidase and makes glyconic acid and H202. then H202 uses peroxidase to produce a color change which is directly proportional to the glucose concentration in the sample
Glucose oxidase reaction
High levels of what contribute to decreased readings
high levels or bilirubin, uric acid, and ascorbic acid all contribute to decreased readings
Oral glucose tolerance test
The patient must be
Fasting
Oral glucose tolerance testing
Fasting samples are drawn and the patient
drinks 100 grams of glucose and then samples are drawn at 30 minutes, 1 hour, 2 hours, and 3 hours after the drink is consumed.
Oral glucose tolerance testing
not recommended by the
ADA to diagnosis diabetes, but its commonly used to screen for gestational diabetes
Oral glucose tolerance testing
sometimes a 2 hour
Postprandial challenge is performed instead, where you use 75 grams of glucose, and then one sample is drawn 2 hours after the drink is consumed
Glycosylated hemoglobin
A1c
glycosylated hemoglobin A1c
long-
Long term blood glucose regulation followed by measurements of glycosylated hemoglobin
glycosylated hemoglobin A1c
A good way to monitor how a
A Diabetic patient managed their sugar levels over the long haul
glycosylated hemoglobin A1c
Essentially the glucose sticks
to the hemoglobin
glycosylated hemoglobin A1c
The reaction does not
Require a enzyme
glycosylated hemoglobin A1c
Gold standard for measurement
HPLC
glycosylated hemoglobin A1c
If a patient has a condition effecting blank shouldn’t be monitored this way
RBC survival shouldn’t be monitored this way
glycosylated hemoglobin A1c
Reference range
4.0-6.5%
Other tests include of glucose testing
ketone testing
Ketone testing
produced by the
liver through the metabolism of FAs
Ketones provides
ready energy source from stored lipids
Ketones increase
with carbs deprivation, or decreased carbohydrates use ( diabetes, dehydration, starvation, and high fat diets)
3 ketone bodies
Acetone, acetoacetic acid, and BHOB
Ketones measured in
urine and serum/plasma
Triglyceride functions
Major form of what
Primary function
The human body stores large amounts of blank and this form for reserve energy is
-Major form of fat found in nature
-Primary function is to provide energy for the cell
-The human body stores large amounts of fatty acids in ester linkages with glycerol in the adipose tissue. This form of reserve energy storage is highly efficient because of the magnitude of the energy released when fatty acids undergo
Triglyceride clinical significance
-Triglyceride testing is used to understand your risk for heart disease, stroke, and other conditions that involve your arteries, such as PAD (Peripheral Arterial disease)
-Also used to help monitor heart conditions and treatments to lower the risk of heart disease
Triglyceride adult levels
adults<150mg/dl
TG kids and teens level
kids<90mg/dl
Borderline TG level
150-190mg/dl
High TG level
200-499mg/dl
Extremely high TG level
> 500mg/dL
What causes elevated Triglyceride values
-Drinking too much alcohol
-Eating too many refined carbohydrates (white breads), sugars, or saturated fat combined w/ a sedentary lifestyle
-Genetics
-Certain medical conditions like diabetes, hypothyroidism, Lupus, Liver or Kidney disease, RA, or obesity
-Medications (2nd gen. Antipsychotics I.e. clozapine, Antiretrovirals, Corticosteroids, Beta blockers, etc.)
Triglyceride possible treatment options
-Lifestyle Changes
-Avoid alcohol, refined carbs and sugars
-Eat more seafood that contain omega- 3 fatty acids.
Exercise more often lose weight
-Medications: Fibrates or Statins
Chemistry assays that can be affected by extreme lipemia
-In cases of Extreme Lipemia, the following testing cannot be reported (UNLESS IT CAN BE REMOVED OR DILUTED)
Albumin
Total Bilirubin
Cortisol
HDL
Lactic Acid
Phosphorus
Vitamin D 25-OH
Triglyceride
How do you remove them from your sample
-Diltuions
-High Speed Centrifugation: 10000 xg for 15 minutes
-Ultracentrifuge: Higher speed centrifuge which effectively separates the larger molecules like lipids from the patient serum or plasma
-Chloroform: YES SERIOUSLY….BUT FOR OBVIOUS REASONS WE DON’T USE THIS IN THE CLINICAL SETTING
-Lipoclear: a polar solvent that can be used to separate lipids from the aqueous in lipemia samples (you just mix it with your sample and spin), but it can interfere with other tests such as GGT, CRP, and CK
Cholesterol biological function
-Structural component of cell membranes
-Serves as a building block for synthesizing various steroid hormones and Vitamin D, and bile acids
Cholesterol clinical significance
Total cholesterol is measured in a clinical setting to help determine your risk of developing heart disease. It can determine your risk of the build up of fatty deposits (plaques) in your arteries that can lead to narrowed or blocked arteries throughout your body (atherosclerosis). If one of the plaques burst, a blood clot may form that may block the artery completely or travel to other parts of the body causing heart attack, stroke vascular dementia, or limb los
Cholesterol normal range
less then 200mg/dl
Cholesterol borderline to elevated
200-239mg/dl
high cholesterol value
above 240mg/dl
high cholesterol value
above 240mg/dl
Cholesterol elevation causes
Poor diet Eating too much-saturated fat or trans fat
Obesity
Lack of Exercise
Smoking
Alcohol
Age
Cholesterol
ways to reduce cholesterol
-Heart healthy eating Limiting trans and saturated fats
-Weight Management
-Increase Physical Activity
-Managing Stress
-Quit Smoking
-Reduce Alcohol Intake
Triglyceride and cholesterol AMR and CRR
-AMR: (Linearity ) Analytical Measurable Range of your chemistry analyzer (or the methodology of the reagent it uses)
-Clinical Reportable Range: Results outside the CRR will be reported as a less than or greater than. Dilutions performed by the chemistry analyzers are performed using Saline
Triglyceride
AMR 7-1400 mg/dL
Max Dilution 1:4
CRR 7-5600 mg/dL
Triglyceride and Cholesterol AMR and CRP continued
Cholesterol AMR and CRP
Total Cholesterol
-AMR 5-700 mg/dL
-Max Dilution 1:4
-CRR 5-2800 mg/d
Triglyceride and cholesterol acceptable specimen types and stability
-The preferred specimen type in the clinical laboratory setting is Lithium Heparinized Plasma or Serum.
-Triglycerides: 2 days RT, 7 days refrigerated, 1 year frozen
-Cholesterol: 7 days RT, 7 days refrigerated, 3 months frozen
Marked elevations of AST and ALT are associated with
Marked elevations of AST and ALT are associated with hepatocellular disease or damage to hepatocytes
Marked elevation of ALP is associated with
Marked elevation of ALP is associated with hepatobiliary disease or obstructive liver disease.
Hepatocellular diseases
liver cancer, cirrhosis
Hepatobiliary diseases
: a group of conditions affecting the bile duct, pancreas, and gallbladder
AST can also be elevated in
myocardial diseases such as Congestive heart failure, pericarditis, and myocardial infarctions
Viral hep, cirrhosis, alcoholic hep and reyes syndrome are examples of
AST elevations.
second most common cause of AST elevation
Steatohepatitis
Muscle diseases associated with AST elevations are
Muscular dystrophy and skeletal muscle injury.
ALT is more
What is hugest elevations
Specific then AST and acute viral hep and toxic hep is highest elevations
ALT is more
Specific then AST and acute viral hep and toxic hep is highest elevations
AST and ALT can be elevated before
Liver cancer
AST is routinely measured using a modification of the
blank is the Indicator reaction
and measured ABS as a decrease in blank
Karmen method with the addition of coenzyme P-5-P to ensure full catalytic activity
Malate dehydrogenase is the indicator reaction the measures the decrease in absorbance at 340 nm as NADH is oxidized to NAD+, which is directly proportional to the AST activity
AST methodology
1.) L-aspartate + a-ketoglutarate with enzymes Asoatate aminotransferase and P-5-P <——-> Oxaloacetate + L-glutamate
2.) Oxaloacetate + NADH + H+ with enzyme Malate dehydrogenase ——> Maltate + NAD+
ALT methodology
ALT is routinely measure with a modification of Wroblewski and LaDue using lactate dehydrogenase as the indicator reaction
The decrease in an absorbance is measured at 340 nm as NADH is oxidized to NAD+
ALT reaction
1.)Alanine + a-ketoglutarate with enyzme Alanine aminotransferase and P-5-P —–> Pyruvate + L-Glutamate
2.) pyruvate + NADH with enzyme Lactate dehydrogenase ——-> L-Lactate + NAD+
AST and ALT reference range
AST: 37C is 5-30 U/L
ALT: 37C is 6-37 U/L
Hemolysis should be avoided in AST because AST
is 10-15 times higher in RBCs than in serum
Hemolysis should be avoided because ALT levels
In RBCs are 5-8 times higher than serum levels
AST is stable at room temperature for
48 hours and 3-4 days at refrigerator temperature
ALT should be measured witin
24 hours because activity decreases in refrigerated temperatures but is stable when frozen at -70 degrees C
CRP is what
Clinical reportable range
AMR is
Analytical measurable range
AST: CRP=
AMR because it has no validated dilution
ALT: CRP requires a
1:5 dilution
All to report
The highest to report is the high end of the clinical range.
Enyzmes sometimes have
Absorbance errors
Using cellulose acetate, serum proteins can be
separated into 6 fractions
six fractions of serum protiens
Albumin with higest peak, then Alpha1, alpha 2, Beta, and gamma
Beta can be subdivided into
Beta 1 and Beta 2
Albumin range range
3.2-5.0 g/dL
Alpha 1 globulins range
0.1-0.4 g/dL
Alpha 2 globulins range
0.6-1.0 g/dL
Beta globulins range
0.6-1.3g/dL
Gamma globulins range
0.7-1.5 g/dL
Albumins low molecular weight confers that
It migrates most Anodally
Albumin forms complexes with
Many proteins and permitting transport of calcium and Billary pigments.
Albumin plays a role in
Maintaining blood volume and osmotic pressure
gamma globulins are also called
Immunoglobulins IgM
Globulins are very
Heterogeneous
Albumin is very
Homogeneous
The rapid breakdown of tissue is frequently found in
Acute inflammation and is characterized by localized biochemical responses such as activation of complement and by cellular responses such as mobilization of phagocytes and increased in protein synthesis.
Acute inflammation picture
Subacute Inflammation
represents a intermediate stage between two possible courses of inflammation which as total convalescence or recovery and the second being Chromic inflammatory condition
when recovery begins there is a characteristic decrease followed by return to normal of the Alpha 1 globulins, complement, and albumin
Chronic inflammation
Increase in proteins called Chronic phase proteins.
Electrophoretically this is seen as a moderate to slight increase in alpha 2 globulins and a slight increase in the beta globulins
Chronic inflammation
Albumin may be
Slightly suppressed with a polyclonal increase in gamma globulin
Chronic inflammation picture
Liver is the site of
Albumin and Alpha globulin synthesis
The liver has significantly what
reserve synthesis capacity
Decreased Albumin is only seen in
Advanced hepatocellular diseases
Acute viral hepatitis
Increased levels of IgG and IgM
Chronic liver disease
marked increase in IgG,M,A with a decrease in albumin and transferrin
Biliary destruction
increased levels of C4 and beta lipopotien
Liver disease picture
Nephrotic syndrome
involves a large loss
involves a large loss of Albumin from the kidneys
nephortic syndrome can be caused by
Diabetes Mellitus, Connective tissue disease, glomerular disease, and circulatory diseases.
Nephrotic syndrome is characterized by
Hypoproteinemia
edema
Hyperlipedemia
Proteinuria
Albumin and other low molecular weight proteins are lost through the glomerular tubules in
Nephrotic syndrome therefore there is a increase in large molecular weight proteins ( IgM, macroglobulin, and Lipoproteins)
Nephrotic syndrome
The electrophoresis pattern may be
Mimicked by acute inflammatory conditions when increased alpha 1 and 2 globulins
Nephrotic syn picture
Hypogammaglobulinemia and Agammaglobulinemia
are characterized by
decreased amount of all immunoglobulins.
Hypogammaglobulinemia and Agammaglobulinemia
examples in infants
Wiskott aldrich syndrome, Brutons disease, ataxia telangietasia
Hypogammaglobulinemia and Agammaglobulinemia
accuquired in childhood
monoclonal gammopathies, or induced by immunosuppressive therapy
Bence jones proteins
are found in adults with hypogammaglobulinemia
Monoclonal gammopathies
proliferation of B lymphocytes
electrophoresis shows one homogeneous peak
decreased in normal immunoglobulins
Homogenous paraproteins are formed from a single type of heavy chain that filters through the glomerular tubules and forms
Bence jones proteins( free light chains
Electrophoresis is not suitable for
Biclonal gammopathies Immunoelectrophoresis or Immunofixation must be performed.
Immunofixation electrophoresis consists of
Agarose gel electrophoresis followed by immunoprecipitation by direct application of specific antisera
Polycolonal gammopathies are characterised by
Broad, diffuse increase in the gamma region of IgG, A, M.
After hypoalbyminemia, polyclonal gammopathy is the most common protein abnormality
Polyclonal gammopathies are seen in
Chronic liver disease
Collagen disorders
Chronic infections
metastatic carcinoma
cystic fibrosis
thermal burns during recovery stage
In heterozygous individual alpha one antitrypsin is decreased
30-50%
Homozygous individual alpha one antitrypsin deficiency
can decrease as much as 80-90%
Homozygous individual are exposed to pulmonary emphysema
Acquired alpha one antitrypsin deficiencies
Nephrotic syndrome
Phenotyping done by 2-dimensional immunoelectrophoresis is done or by isoelectrofocusing in polyacrylamide gel
A super-high serum sodium low ca2+ and Mg2+ usually indicative of low
accidentally placing specimen into wrong tube. or nurse dumps tube into another one.
potassium chelates Mg2+ and Ca2+
Hemolysis is the most encountered
Artifact in the lab, can be as high as 3.3% of all routine samples , thus accounting for 40-70% of all unsuitable samples identified.
Rejection of in vivo hemolysis is considered
Malpractice
In vivo
Inside the body
In vitro
Outside the body
Icteric is
Jaundice= yellowish color of the eyes
very high bilirubin concentrations
A dextrose solution (sugar) IV infusion would yield
extremely high glucose results results in venous specimens
Collected above or near the Infusion site
Total parenteral nutrition (TPN) fluid contains most
of the required daily nutrients for a person who cant ingest food
TPN fluid contamination in a specimen creates gross turbidity along with elevated lipid and glucose values and potassium levels too high to be compatible with life (< l.3 and > 9 mmol/l “ RI 3.5-5.0mmol/L).
Have to turn off TP< machine first before chemistry lab testing
In specimens from a patient receiving a saline IV infusion
Sodium and chloride results will be falsely elevated due to contamination from saline IV fluid.
Lipemic plasma
will appear milky white
the most common cause of lipemic samples Is that the patient has not fasted.
Hemolysis impacts lab testing because
Increase in intracellular analytes such as Aspartate aminotransferase, Lactate dehydrogenase, and Potassium.
released proteases from RBCs can degrade proteins such as insulin and cardiac troponin.
The presence of hemoglobin can interfere with spectrophotometric readings
Lipemic samples interfere with
increase light abs and decrease light Transmittance.
can cause volume discrepancies
severe lipemic samples are more prone to hemolysis.
