Day 1 Flashcards
Accuracy and precision relate to QA or QC?
QC - looks at the accuracy and precision of analyzers
State regulations are overseen by… National regulations are overseen by…
LFS (Dept of Health)
CLIA, enforced by CMS
What hospital standards are nurses and hospital staff more familiar with? Clinical labs?
JCAHO
CAP
Plasma is collected in the tube with this colored cap… Serum is collected in the tube with this colored cap…
Purple
Red
A blood tube that is yellow in color is due to…
Icterus (bilirubin)
A blood tube that is red in color is due to…
Hemolysis
A blood tube that is turbid is due to…
Lipemic
What will happen if a calcium test is collected in an EDTA (purple top) tube?
Absorbs calcium, value very low
- erroneous results
- anti-coagulants become involved in testing
3 types of spectrophotometry measurements
Colorimetric
Endpoint
Initial Rate
Colorimetric - measuring absorbance of an ___
Analyte
Endpoint - measuring absorbance of some ___ with the analyte, then calculating the concentration of the analyte using reaction formula
Product of a reaction
Initial rate - measuring the ___ over time, then using that rate to calculate analyte concentration
Change in absorbance
Proteins absorb UV at this wavelength
280 nm
The BUN measurement is this type of spectrophotometric measurement
Initial rate
-rate can be positive or negative, depending on measurement of product or reactant
Turbidity vs nephelometry - what does each measure?
Turbidity = light absorbed/blocked
Nephelometry = light scattered
How are reference intervals determined?
Mean +/- 2 SD
- accepts 95% of population, excludes 5%
- values from 120 patient population
What is a delta check? Delta checks are useful for determining pre-analytical, analytical, or post-analytical errors?
Review of previous results, looking for a relative change of an analyte
-tells us if analyzer has changed significantly
Pre-analytical and analytical
What are the 6 types of reagent grade water as classified by CLSI?
Clinical laboratory reagent water (CLRW) Special reagent water (SRW) Instrument feed water Manufacturer supplied Autoclave/wash Commercially purified/bottled
Thirst is stimulated by this part of the brain… Which is in response to this physiological condition…
Hypothalamus
Increased osmolality of blood
- due to elevated sodium level
- drinking water increase water content of extracellular fluid, diluting sodium and decreasing osmolality of the plasma
This hormone, ___, acts on the cells of the collecting ducts of the kidneys to increase water reabsorption to decrease osmolality. The hormone is secreted by…
Vasopressin (ADH = antidiuretic hormone)
Posterior pituitary gland
-hormone made in hypothalamus first
Where is aldosterone made? What does aldosterone do? How is it different than vasopressin?
Adrenal gland
Causes nephron distal tubules to reabsorb sodium and water
- absorb salt first, which causes water to follow via osmosis
- increases blood volume
Vasopressin reabsorbs water
Aldosterone reabsorbs Na and water
Cushing’s disease and Addison’s disease both involve this organ…
Adrenal gland
-disorders are opposite of each other
What is seen in Cushing’s disease and Addison’s disease in terms of the amount of hormones being released?
Cushing’s disease = excessive cortisol release
-mnemonic: Cushing’s = cortisol
Addison’s disease = low cortisol AND low aldosterone
What are natriuretic peptides?
Compounds that cause sodium excretion in urine. Compounds have an opposite effect to the Renin-angiotensin-aldosterone system
- pee out more water
- similar to diuretic, except pee is salty
Diabetes insipidus is due to deficiency in which hormone? What is a common symptom of the disease?
ADH (vasopressin)
- disruption in production, release, breakdown, or cells responding to
- 4 main categories
Always thirsty, even after drinking
- pee a lot
- very dilute urine
What is the name for the force that tends to move water from dilute solutions to concentrated solutions?
Osmotic pressure (osmosis)
How many mOsm (milliosmoles) per kg are present for the following compounds, each at 15 mmole solute per kg water: glucose, NaCl, CaC12
Glucose: 15 mOsm/kg
-1 ion only
NaCl: 30 mOsm/kg
-dissociates into 2 ions
CaCl2: 45 mOsm/kg
-dissociates into 3 ions
Osmolality can be measured in two ways
Freezing point depression
-1 osmol of solute/kg lowers freezing point of water by 1.86C
Vapor pressure depression
- solute added to solvent
- vapor press of solvent in equilibrium with liquid phase decreased
What is the osmolal gap? What is the normal osmolal gap?
The difference between the osmolality of blood that is measure vs what is calculated
-something else in the blood not taken into account in calculation
< 10 mOsm/kg = normal
> 10 mOsm/kg = abnormal (abnormal concentration of unmeasured substances)
Which are extracellular and which are intracellular: chloride, phosphates/proteins, potassium, sodium, bicarbonate (HCO3-), magnesium
Extracellular: chloride, sodium, bicarbonate
Intracellular: phosphates/proteins, potassium, magnesium
Name an extracellular buffer. Name an intracellular buffer
Bicarbonate (HCO3-)
Phosphates/proteins
What would falsely increase in a hemolyzed specimen?
Intracellular ions
-potassium, phosphates/proteins
Difference between osmosis and diffusion? What is active transport?
Diffusion = passive movement of solutes
Osmosis = passive movement of fluids
Active transport = uses ATP (active) to move solutes against concentration gradient
In any compartment, the total charges of positive and negative electrolytes must be ___
Equal
The electrolyte balance in blood, serum or plasma is determine by the ___ measurement
Anion Gap
- sum of “routinely measured” cations minus the sum of the “routinely measured” anions in the blood
- value must always be positive; negative values may indicate lab error interference
Why is it okay to normally leave potassium out of the anion gap calculation?
Potassium values low and intracellular
-increased during hemolysis or tissue damage
When sodium is above the renal threshold, is blood sodium is high or low? Will sodium show up in the urine?
High
Yes
-excreted
When sodium is below the renal threshold, is blood sodium is high or low? Will sodium show up in the urine?
Low
No
- kidneys reabsorb sodium
- should see some sodium in urine in healthy people
Is a mildly hemolyzed specimen acceptable for a sodium measurement? Is a severely hemolyzed specimen acceptable for a sodium measurement?
Yes
-most sodium is extracellular
No
- will dilute sodium in serum
- lowers measured value
What is the term for high sodium? 3 main causes for high sodium levels…
Hypernatremia
Excess water loss
Decreased water intake
Increase intake/retention of sodium
What is the term for low sodium? 3 main causes for high sodium levels…
Hyponatremia
Excess sodium loss
Increased water retention
Water imbalance
Excess of interstitial fluid, locally, due to inflammation, hypersensitivity or venous blockage is called…
Edema
In diabetes insipidus, sodium levels are __ in the blood and osmolality is ___ in the urine
High
Low
Why would a person with diabetes (hyperglycemia) have hyponatremia?
High glucose in blood increases blood osmolality, which causes water to flow into blood due to osmosis, diluting serum sodium concentration
What do hypervolemia and hypovolemia mean?
Hypervolemia = too much fluids in blood
Hypovolemia = too little fluids in blood
Is transport of potassium into cells in exchange for sodium an active or passive transport?
Active
-sodium-potassium pump
What is the renal threshold for potassium?
None
Is a hemolyzed specimen acceptable for a potassium measurement? Why or why not?
No
Potassium is intracellular
-falsely high potassium results
Do kidneys reabsorb potassium? Why or why not?
No
Very little potassium in blood, most intracellular
-easily replenish blood potassium with daily intake
What is the term for high potassium? 2 main causes for high potassium levels…
Hyperkalemia
Decreased renal excretion
Cellular shift
-false elevation: hemolysis, thrombocytosis, fist clenching
What is the term for low potassium? 3 main causes for low potassium levels…
Hypokalemia
GI loss
Renal loss
Cellular shift
In cystic fibrosis patients, if we measure their sweat, we can see this electrolyte has increased
Chloride
Increased chloride is called… Decreased chloride is called…
Hyperchloremia
-compensate loss of HCO3-
Hypochloremia
-vomit, diabetic ketoacidosis, aldosterone deficiency, pyelonephritis
Chloride closely follows the patterns of this other electrolyte…
Sodium
When this molecule, ___, is used up trying to balance blood sodium, chloride can be used to compensate
Bicarbonate (HCO3-)
- consumed by reaction with H+ produced in metabolic acidosis
- increased Cl- reabsorption (Na+ with Cl-)
Where is magnesium mostly found?
Bone, tissue
- very little in blood
- extracellular magnesium used to maintain intracellular levels
Increased magnesium is called… Decreased magnesium is called…
Hypermagnesemia
Hypomagnesemia
ISE is a method used to measure bound or free electrolytes?
Free (ionized)
- one electrode is selective for ion
- other electrode is reference
Increased calcium IN BLOOD is called ___. Increased calcium IN URINE is called ___.
Hypercalcemia
Hypercalcuria
Are phosphates/phosphorus mostly extracellular or intracellular?
Intracellular
When glucose levels in the blood goes above the renal threshold, it will appear in the ___, and the condition is called…
Urine
Glucosuria
High blood sugar stimulates the release of this hormone, ___, which triggers the production of… Low blood sugar stimulates the release of this hormone, ___, which triggers the release of…
Insulin = glycogen
Glucagon = release stored glycogen
-glycogen converted into glucose
Diabetes mellitus - what is the classic triad of symptoms? Are these symptoms seen in Type I or Type II?
Excessive urination (polyuria) Excessive thirst (polydypsia) Excessive hunger (polyphagia)
Type I diabetes
Do ketones go up or down with Type I diabetes mellitus? Why?
Up
Body thinks it’s starving due to lack of insulin, breaks down lipids for energy
-lipid breakdown = pH decrease (ketoacidosis)
Is the anion gap increased or decreased with diabetes mellitus?
Large increase
- ketone bodies increase
- potassium goes out of cells to compensate for low pH due to ketoacidosis
- bicarbonate decreased to reduce negative charges
In renal diabetes, the blood glucose level is ___, and the urine glucose level is ___. Why?
Normal
High
Glucosuria due to low sugar threshold in kidneys
- kidneys fail to reabsorb normal amount of glucose back into blood
- glucose above threshold excreted into urine
Is glucagon increased or decreased in diabetes mellitus?
Increased
- body thinks it’s starving due to insulin deficiency
- in both Type I and II diabetes
Difference between Type I and Type II diabetes
Type I = insulin deficiency
- from autoimmune disease
- usually before age 20
- ketones and glucagon present
Type II = insulin resistance
- acquired diabetes
- insulin and glucagon present
In both Type I and Type II diabetes mellitus, the blood glucose is… The urine glucose is…
Hyperglycemic
Glucosuria
The gold standard test for diabetes mellitus is…
A1C
- higher glucose conc = higher A1C level
- < 7% of total hemoglobin in healthy people
- may falsely increase in certain conditions, pregnancy
What is hemoglobin A1C?
Glycosylated hemoglobin
- glucose molecules stick to hemoglobin
- reflects average glucose over 6-8 week period
- cutoff at 6.5% = good sensitivity/specificity
How does the oral glucose tolerance test (OGTT) work?
Give patient 100g glucose orally
- draw blood at specific interval
- establishes when glucose reaches highest concentration and how rapidly it returns to normal levels
What are the OGTT test results for a normal person vs a diabetic?
Normal - venous blood sugar does not exceed 200 mg/ 100 ml blood. Returns below 120 mg in 2 hours
Diabetic - glucose level peaks above 200 mg. Does not return below 120 mg after 2 hours
What is the precursor form of insulin called? What does it break down into (2)?
Proinsulin
Insulin
C-peptide
How can we tell if insulin is made endogenously vs exogenous insulin from an insulin shot?
Endogenous insulin - proinsulin breaks down into insulin and c-peptide. C-peptide can be measured
Exogenous insulin - no c-peptide
What is gestational diabetes and when does it resolve?
Insulin resistance due to hormones blocking insulin’s effect (similar to Type II diabetes)
-begins around 20-24 weeks
Resolves after delivery
-hormone levels return to normal
What is the term for ketones in the urine? Is this condition present in Type I or Type II diabetics?
Acetouria
Type I only
Vomiting causes the loss of this electrolyte and can cause this condition
Chloride = hypochloremia
Plasma vs serum tubes - which one has anti-coagulants added? Which one is devoid of fibrinogen and other clotting factors?
Plasma
Serum
In addition to stimulating glycogen release, glucagon also promotes the enhancement of this process to make more glucose…
Gluconeogenesis
What does the potassium-hydrogen ion exchange do? Under what condition is it used?
K pumped out of cell and H+ go into cells to increase blood pH
Acidosis
What test should we use to distinguish bacterial from viral meningitis?
CSF glucose testing
- bacteria = low (< 40% of serum glucose)
- viral = normal
Besides Type I diabetes, ketones appearing in the urine can also be as indicator for…
Congestive heart failure
-also ketogenic diet
What is the best anticoagulant for potassium?
Heparin
-EDTA causes huge potassium spike
Which electrolyte is the major extracellular anion?
Chloride
