liver function, enzymes, electrolytes Flashcards
bile is stored in what organ?
gallbladder
liver function tests are usually based on which principle?
photometry
formula for total bilirubin
TB = CB + UB
normal value for total bilirubin in adults
0.2 - 1.0 mg/dL (3-17 umol/L)
jaundice is clinically evident when bilirubin level exceeds _
2.0 mg/dL
in the liver, bilirubin is conjugated by addition of _
glucuronyl groups (glucuronic acid)
enzyme responsible for conjugation of bilirubin
UDPGT
bilirubin fraction increased in pre-hepatic (hemolytic) jaundice
unconjugated / B1 / indirect
bilirubin fraction increased in hepatic jaundice
unconjugated / conjugated
bilirubin fraction increased in post-hepatic (obstructive) jaundice
conjugated / B2 / direct
bilirubin fraction that does NOT require an accelerator to react
conjugated (direct) bilirubin
form of bilirubin that is soluble in water
conjugated bilirubin
form of bilirubin that is insoluble in water
unconjugated bilirubin
bilirubin fraction covalently attached to albumin
delta bilirubin
other name for delta bilirubin
biliprotein
form of bilirubin that has longer half-life than other forms of bilirubin
delta bilirubin
disease characterized by a defect in bilirubin transport or uptake by the liver
Gilbert syndrome
disease characterized by the absence of the enzyme needed for bilirubin conjugation
Crigler-Najjar syndrome
disease characterized by a defect in bilirubin excretion into the bile duct
Dubin-Johnson (& Rotor) syndrome
elevation of bilirubin in newborns (due to immature liver)
physiologic jaundice
kernicterus is an abnormal accumulation of unconjugated bilirubin in the _
brain tissues
neonatal bilirubin level is 28 mg/dL; when will you report the result?
immediately
the danger of kernicterus is a certainty at bilirubin levels exceeding _
20 mg/dL
these are proteins produced by living cells that hastens chemical reactions in organic matter
enzymes
preferred specimen for enzyme determination
serum
phase in which enzyme activity is usually measured
linear phase
SI unit for measuring enzyme catalytic activity
Katal (K)
two general methods that are used to measure the extent of an enzyme reaction
fixed-time & kinetic assays
multiple measurements of change in absorbance are made during the reaction (method)
continuous-monitoring assay / kinetic
reactants are mixed; reaction proceeds for designated time; reaction is stopped & measurement is made (method)
fixed-time assay
enzyme data interpretation (3)
- there is no truly “organ-specific” enzyme
- NEG results are useful
- data must be integrated with other info
macroenzymes (9)
GoodLLAAAAACK
GGT, LPS, LDH, AST, ALT, ALP, ACP, AMS, CK
ALP isoenzyme electrophoretic pattern (anode to cathode)
LBPI
liver > bone > placental > intestinal
ALP isoenzyme heat stability (most heat stable to most heat labile)
PILB
placental > intestinal > liver > bone
levamisole inhibits what ALP isoenzyme(s)?
liver & bone ALP
phenylalanine inhibits what ALP isoenzyme(s)?
placental & intestinal (Regan) ALP
3M urea inhibits what ALP isoenzyme(s)?
bone ALP
buffer used in ALP analysis
AMP (amino methyl propanol)
physiologic (increase / decrease) in serum ACP has been reported in specimens obtained from patients after rectal exam
increase
ACP determination is also useful in _
forensic clinical chemistry; rape cases
effect of high concentration of bilirubin & hemoglobin to ACP determination
increased (specimen is hemolyzed)
enzyme that catalyzes the conversion of starch to glucose and maltose
amylase
enzyme that is best indicator of pancreatic function
lipase
(+) result in the turbidimetric method for lipase
clearing / decrease in cloudiness
least specific enzyme (found in many tissues)
LDH (lactate dehydrogenase)
causes of flipped LD pattern (4)
AMI
renal infarction
megaloblastic anemia
hemolytic disorders
major tissue sources of AST (3)
cardiac tissue
liver
skeletal muscle
liver-specific enzyme
ALT
old name for AST (aspartate aminotransferase)
SGOT (serum glutamic-oxaloacetic transaminase)
old name for ALT (alanine aminotransferase)
SGPT (serum glutamic-pyruvic transaminase)
enzyme indicator used in measuring ALT activity
LDH (lactate dehydrogenase)
enzyme indicator used in measuring AST activity
MD (malate dehydrogenase)
more sensitive and specific screening test for post-transfusion hepatitis
ALT
enzyme increased in alcoholism
GGT
enzyme whose significance is decreased activity (organophosphate poisoning)
pseudocholinesterase
(+) result in the turbidimetric method for lipase
decrease in turbidity
chloride shift is maintained by a reversible exchange process betweer _
bicarbonate and chloride
anion gap formula and its normal value
(Na + K) - (Cl + HCO3); 10-120 mmol/L
anion gap formula and its normal value
Na - (Cl+ HCO3); 7-16 mmol/L
it is the difference between the unmeasured cations (Na &K) & unmeasured anions (Cl & HCO3)
anion gap
it is a form of quality control for the analyzer used to measure these electrolytes
anion gap
blood gas disorder most commonly associated with an abnormal anion gap
metabolic acidosis
hypernatremia occurs when serum sodium is _
> 145 mmol/L
hyponatremia occurs when serum sodium is _
> 135 mmol/L
hormone that regulates sodium reabsorption
aldosterone
relationship ADH and sodium levels
inverse
effect of low ADH on serum sodium
increased sodium
effect of high glucose on serum sodium concentration
decreased sodium
promotes natriuresis, blocks aldosterone secretion, inhibits vasopressin
atrial natriuretic factor
hyperlipidemia causes artifactual _
hyponatremia
low sodium caused by pseudohyponatremia, what to do?
test for osmolality
electrolytes, BUN, CREA, osmolality are done on patient who ingested ethanol, what to do?
determine Osmolal gap
electrolyte that transmits nerve impulses
potassium
marked hyperkalemia may lead to _
cardiac arrest
what electrolyte is falsely-increased in hemolyzed blood samples
potassium
factors affecting serum calcium levels include (3)
vitamin D (increase)
parathyroid hormone (increase)
calcitonin (decrease)
Milk-alkali syndrome may lead to _
hypercalcemia
a pro-oxidant contributing to DNA damage, lipid peroxidation, carcinogenesis, etc.
iron
it regulates intracellular iron transport from intestinal surface to inside the cell
DMT-1
for lactate testing, blood should be collected in a tube containing _
10 mg NaF & 2 mg K2C2O4 per mL of blood
it refers to a dissociable substance that can yield hydroxyl ions (OH)
base
a substance that can yield hydrogen or hydronium ion when dissolved
acid
most important buffer pair in the plasma
HCO3:H2CO3 pair (bicarbonate to carbonic acid)
weak acid or base & their related salts; resists any changes in pH & H+ ion concentration
buffer
blood buffers include (5)
BC PHI
bicarbonate
carbonic acid
plasma proteins
hemoglobin
inorganic phosphate
it is the primary substance in the carbonic acid-bicarbonate buffer system
bicarbonate
normal ratio of bicarbonate buffer system
20:1
during onset of fever, pCO2 increases by _ and pO2 decreases by _
3%, 7%
electrode used for pH
glass electrode
electrode used for pCO2
Severinghaus electrode
electrode used for pO2
Clark electrode
electrode used for K
Valinomycin-based electrode
used to calibrate pH meter
buffer
anticoagulant of choice for arterial blood gas measurements
lithium heparin (dry/lyophilized)
most common preanalytical error in blood pH measurement
excess heparin
when a blood sample is exposed to air, pH and pO2 levels _ while pCO2 _
increases, decreases
when a capped blood is allowed to stand at RT, pH & pO2 levels _ & pCO2 _
decreases, increases
