01 - renal fx (chem)

Question 1

(BUN)

1. what 3 things ^ BUN?
2. affected by production in what organ?

Answer 1

1. ↓ GFR, ^dietary protein, GI bleeding
2. liver

Question 2

(creatinine)

1. ^ means what % renal fx remains?
2. lower in older or younger?
3. what can cause low values?

Answer 2

1. less than 25% (normal value doesn’t exclude renal dz)
2. young
3. cachexia

Question 3

(serum phosphorus)

1. increase not seen until when?
2. tubular reabsorption regulated by what?
3. Why can conc be higher in immature animals?

Answer 3

1. more than 85% of nephrons are non-fx
2. PTH
3. bone growth

Question 4

(endogenous vs exogenous determination of renal clearance)

1. which is better?
2. what do you do in endo?
3. in exo?
4. what is considered the gold standard?

Answer 4

1. exo
2. collect urine for 24 hrs and determine serum and urine creatinine conc
3. creatinine administered subq or IV and then urine collected via catheter 3 times at 20 minute intervals
4. inulin - but no one does this

Question 5

(urine osmolality)

1. usually linear relationship with what?
2. when will USG be higher?

Answer 5

1. USG
2. when lots of large MW solutes (glucose, mannitol, etc)

Question 6

1. what is azotemia?

Answer 6

1. high levels of nitrogen containing compounds (urea, creatinine, other waste)

Question 7

1. what cases pre-renal azotemia?
2. what causes primary azotemia?
3. what causes postrenal azotemia?

Answer 7

1. decreased blood flow to kidneys
2. primary kidney dz (acute renal failure)
3. blockage of urine flow below the kidneys

Question 8

(excretion of electrolytes - Na)

1. difference in prerenal and primary?

Answer 8

1. prerenal -> will be sodium conservation
2. primary -> excretion higher than normal

Question 10

(excretion of electrolytes - K)

1. useful in chronic renal failure patients to see if kidneys are contributing to hypokalemia

Question 11

(urinary enzymes)

1-2. what two enzymes are specific for renal tubule dmg?

Answer 11

1. GGT and NAG