Biochemical Assessments Pt. 1

Question 1

what is plasma?

Answer 1

the unclotted fluid minus RBC + WBC

Question 2

what is serum?

Answer 2

any fluid left after clotting has occurred

Question 3

what is sensitivity?

Answer 3

the ability of a test to detect a condition when it is present in a patient
high sensitivity = minimal false negative results

Question 4

what is specificity?

Answer 4

the ability of a test to rule out the presence of a disease in someone who does not have it
high specificity = minimal false positive results

Question 5

what is inter-assay variability?

Answer 5

the error you get when you do different measurements

Question 6

what is a static assay?

Answer 6

measures concentration in serum/plasma
i.e. iron, zinc, retinol, folate

Question 7

what can impact static assay measurements?

Answer 7

highly dependent on hydration status
dehydration = artificially high levels
over-hydration = artificially low levels

Question 8

what is a functional assay?

Answer 8

measures biochemical/physiological activity

Question 9

normal serum albumin level

Answer 9

3.5 - 5 g/dL

Question 10

purpose of albumin

Answer 10

maintains colloidal osmotic pressure
carrier for many different substances

Question 11

shortcomings for PEM assessment with albumin

Answer 11

• half-life of ~20 days
• large extravascular pool – can return to circulation and buffer loss
• sensitive to hydration status/edema
• sometimes infused in hospital patients

Question 12

negative/positive acute phase protein: albumin

Answer 12

negative

Question 13

transthyretin (pre-albumin) normal range

Answer 13

normal range: 16 - 40 mg/dL

Question 14

negative/positive acute phase protein: transthyretin

Answer 14

negative

Question 15

purpose of transthyretin

Answer 15

transport thyroxin and retinol-binding protein in blood

Question 16

shortcomings for PEM assessment: transthyretin

Answer 16

• zinc deficiency can affect the synthesis
• increases with chronic renal insufficiency
• decreases with hyperthyroidism

Question 17

purpose of transferrin

Answer 17

transport iron in bone marrow

Question 18

shortcomings for PEM assessment: transferrin

Answer 18

• nonspecific (increases when iron stores are low)
• also increases with estrogen therapy

Question 19

positive/negative acute phase protein: transferrin

Answer 19

negative

Question 20

purpose of retinol-binding protein

Answer 20

binds to retinol in the blood

Question 21

normal range of retinol-binding protein

Answer 21

3-6 mg/dL

Question 22

shortcomings for PEM assessment: retinol-binding protein

Answer 22

• vitamin A status may complicate use
• renal patients may have elevated complications
  *may be the best marker, but it is very expensive

Question 23

positive/negative acute phase protein: retinol-binding protein

Answer 23

negative

Question 24

positive/negative acute phase protein: hs C-reactive protein

Answer 24

positive

Question 25

what is CRP good for?

Answer 25

could be an indicator of when to start nutrition therapy; when CRP subsides, therapy should increase

Question 26

serum enzymes that indicate muscle damage

Answer 26

creatine kinase lactate dehydrogenase

Question 27

serum enzymes that indicate liver damage

Answer 27

alanine amino transferase (ALT) aspartase amino transferase (AST)

Question 28

serum enzymes that indicate pancreatic damage

Answer 28

amylase lipase

Question 29

normal blood glucose levels fasted + post-prandial

Answer 29

fasted: 70-100 mg/dL post-prandial: <140 ~2 hours after meal

Question 30

use of hA1c

Answer 30

indicator of average plasma glucose concentration over previous months (60-90 days)

Question 31

normal hA1c levels (average adult, older adult, with DM, at risk for DM)

Answer 31

average adult: <5.7% older adult: <7% with DM: <7% at risk for DM: 5.7-6.4%

Question 32

how is bilirubin made?

Answer 32

break down of hemoglobin, then released in blood

Question 33

what does elevated unconjugated bilirubin indicate?

Answer 33

elevated when liver is unable to conjugate to glucuronic acid indicative of excessive hemolysis

Question 34

what does elevated conjugated bilirubin indicate

Answer 34

elevated when liver is unable to excrete due to obstruction in the bile passage

Question 35

what does BUN relate to?

Answer 35

protein intake

Question 36

what does elevated BUN indicate?

Answer 36

decreased renal function, dehydration, GI bleeding, CHF, and high protein intake

Question 37

what does low BUN indicate?

Answer 37

liver disease, overhydration, malnutrition, anabolic steroid use

Question 38

what is creatinine?

Answer 38

an oxidized product of creatinine

Question 39

what is creatinine used for (alongside BUN)?

Answer 39

a marker of renal function

Question 40

normal serum sodium levels

Answer 40

135 - 145 mE/L

Question 41

sodium is the primary intra/extracellular anion/cation?

Answer 41

extracellular cation

Question 42

what does sodium do?

Answer 42

helps regulate acid-base balance, osmotic pressure, fluid distribution

Question 43

normal serum potassium levels

Answer 43

3.5 - 5 mmol/L

Question 44

potassium is the primary intra/extracellular anion/cation?

Answer 44

intracellular cation

Question 45

causes of hypokalemia

Answer 45

diuretic use, vomiting, diarrhea, eating disorders, IV administration w/o K -- potentially dangerous

Question 46

causes of hyperkalemia

Answer 46

renal failure, severe injury (burns, crushing), hypoaldosteronism, Addison's dx -- very dangerous

Question 47

causes of hypernatremia

Answer 47

dehydration, excessive fluid loss/output

Question 48

causes of hyponatremia

Answer 48

excess Na loss from body -- vomiting, diarrhea, suctioning, diuretics; H2O/fluid retention; SIADH

Question 49

chloride is the primary intra/extracellular anion/cation?

Answer 49

extracellular anion

Question 50

what is the purpose of chloride?

Answer 50

helps regulate acid-base balance, osmotic pressure, and fluid distribution

Question 51

what is the purpose of potassium?

Answer 51

helps maintain acid-base balance, fluid balance, nerve impulse transmission

Question 52

causes of hypochloremia

Answer 52

alkalosis and hypokalemia; bulemia

Question 53

causes of hyperchloremia

Answer 53

kidney disease, overactive thyroid, CVD

Question 54

phosphorous is correlated with

Answer 54

calcium

Question 55

causes of hyperphosphatemia

Answer 55

with renal failure, hypoparathyroidism, hyperthyroidism, increased phosphorus intake, use of phosphate-containing enemas, laxatives

Question 56

causes of hypophosphatemia

Answer 56

hyperparathyroidism, rickets, osteomalacia, chronic use of antacids containing alumni hydroxide of calcium carbonate also with refeeding syndrome