Clinical Biochem

Question 1

Goal of Serum Electrolytes and What info they give?

Answer 1

maintain a constant osmolality; concentrations give info about: osmolality of ECF (Na+/Cl-), pH (bicarb), and hormonal disturbances ( Ca2+, K+)

Question 2

Sodium and Its Values

Answer 2

principal extracellular cation; main indicator of ECF oncotic pressure; low values = water retention which dilutes body fluids (hyponatremia); high values = dehyrdation

Question 3

Potassium and Its Values

Answer 3

major INTRAcellular ion; important for membrane potential of muscle and nerve cells; 
low values (hypokalemia) = potassium loss by GI or renal;
high values (hyperkalemia)= renal insufficiency (high values effect muscle function and can trigger cardiac arrest

Question 4

CO2 (Bicarb) Values

Answer 4

CO2 conc. indicate acid-base balance of blood; CO2/bicarb system is controlled by lungs (exchange of CO2) and the kidneys (synthesis of bicarb);
must be monitored in diabetic ketoacidosis

Question 5

Calcium Values

Answer 5

affects neuronal and muscular function; concentration is subject to tight hormonal control; 
low values (hypocalcemia)= hormonal disturbances
high values (hypercalcemia)= also hormonal problems but also sign of degradation of calcium stores in skeleton through bone disease or cancer

Question 6

Phosphate Values

Answer 6

mostly stored in bones; high serum phosphate (hyperphosphatemia)= degenerative bone disease, renal failure too;
Low serum values (hypophosphatemia) = impairs glucose metabolism, usually a part of diabetic ketoacidosis, levels must be monitored during treatment w/ glucose infusion

Question 7

Arterial Blood Gases

Answer 7

CO2 conc. from aterial sample;sample can go bad if exposed to air; pCO2 gives info about bicarb system and complements serum bicarb determinations

Question 8

Glucose in Serum

Answer 8

part of standard biochemical panel;risk of developing diabetes;hypo = not enough carb intake or over dose of insulin; hyper = insufficient insulin action

Question 9

Urea (BUN)

Answer 9

excretion of urea and creatinine decreases if kidney function is impaired; therefore, serum urea/creatinine INCREASE while urine values DECREASE; Blood urea nitrogen (BUN) conc. reflect balance between AA degradation and urea production/excretion; if protein intake and catabolism are normal then elevated BUN = impaired renal excretion

Question 10

Creatinine Values

Answer 10

serum creatinine conc. used w/ BUN measure kidney function; increase indicates problem w/ glomerular filtration in kidney; however, very insensitive markers

Question 11

Uric Acid Values

Answer 11

high uric acid = problems w/ renal excretion; gout

Question 12

Direct/Indirect Bilirubin

Answer 12

both usually very low in serum; high values = jaundice and neuronal damage

Question 13

Albumin

Answer 13

produced by liver; 50% of total serum protein;
importance: binds hydrophobic molecules like steroid hormones, FA’s; binding of Ca2+; maintenance of oncotic pressure;
low values = edema since water drawn out of serum and into tissues; hypoalbuminemia stems from liver disease

Question 14

Globulins

Answer 14

hetero mix of proteins secreted by cells of immune system; fluctuate widely in response to cancers/infections; indicate immune system function

Question 15

C-Reactive Protein

Answer 15

secreted by liver; marker of acute metabolic response to injury; useful for following healing process; rise 6 hrs. after injury, peak at 48; sudden rises = complications of healing process

Question 16

Heart Muscle Enzymes and Their use as markers for MI

Answer 16

Myoglobin, Creatine-kinase, aspartate transferase, troponins, lactate dehydrogenase;
myoglobin released quickly after MI (but not heart specific);
Creatine-kinase (CK-MB cardiac isozyme) detectable early after MI but disappears quickly in circulation;
AST released after CK-MB;
Troponins = most sensitive MI marker! detected very early after MI, useful to actually exclude MI as problem, 12 hours after chest pain and no troponins = NO MI;
lactate dehydrogenase isoform released days after MI = late marker

Question 17

Alkaline Phosphatased

Answer 17

increased serum levels = bone or liver disease; comes from gall duct cells or from bone remodeling cells (cancer); bilirubin levels used w/ it to determine if liver or not (liver disease will have high serum levels of bilirubin AND AP)

Question 18

ALT and AST

Answer 18

AST found everywhere tissues 10-fold higher than ALT except [ALT]=[AST] in liver;
high AST and low ALT indicate heart or other muscle damage;
High AST and ALT = liver damage (use bilirubin tests to confirm)

Question 19

Urine Test Components

Answer 19

Glucose: if detectable in urine sign the excretion exceeds renal capacity for reabsorption (hyperglycemia)
Bilirubin: if direct bilirubin found in urine its a pathological finding/biliary obstruction (should be in bile);
Ketones: presence of these show FA breakdown (uncontrolled diabetes or starvation)
Protein: presence sign of renal disease (be sure its not from blood or leukocytes)

Question 20

Basic Metabolic Panel (8 Tests)

Answer 20

kidney function, blood sugar, acid/base:

glucose, Ca2+, Na+, K+, Cl-, CO2, BUN and creatinine

Question 21

Liver Function Test Components

Answer 21

Bilirubin, AST/ALT, Alkaline Phosphatase

Question 22

Kidney Function Test Components and Kidney disease levels

Answer 22

analysis of serum AND urine
BUN/creatinine = increased
serum Na+, K+, HCO3-
urine osmolality

Question 23

Diabetes Test Results

Answer 23

Glucose in urine = present
glycated hemoglobin
proteinuria = protein in urine
C-peptide = amount of it in serum good measure for endogenous production of insulin