Glomerular Filtration Rate and Proteinuria

Question 1

How do you determine Q_excr in the kidney?

Answer 1

Q_excr = UFR x [urine]

Question 2

How do you determine Q_filt in the kidney?

Answer 2

Q_filt = GFR x [serum]

Question 3

If Q_filt = Q_excr, then GFR = ____________

Answer 3

{UFR x [urine]} / [serum]

Question 4

How is creatinine produced and what makes it a good marker of GFR?

Answer 4

Creatinine is produced on a constant basis by metabolism of muscle creatine

It is freely filtered by the glomeruli and minimally secreted by the tubules

Question 5

What are normal values for serum creatinine in…

Men:

Women:

Children:

Answer 5

Men: 0.9 to 1.3 mg/dl or 79 to 114 micromol/L

Women: 0.8 to 1 mg/dl or 70 to 88 micromol/L

Children: 0.5 to 1 mg/dl or 44 to 88 micromol/L

Question 6

Creatinine clearance equation (assuming it is equal to GFR)

Answer 6

Cr cl = {UFR x [urine]} / [serum]

Question 7

If GFR is impaired, how are creatinine levels in the urine maintained?

Answer 7

Increase serum creatinine levels compensate for decreased GFR

Question 8

What is the normal value for GFR?

Answer 8

100 ml/in or 150 liters/day

Question 9

As stages of chronic kidney disease progress, GFR _______

Answer 9

decreases

Question 10

Dialysis is required in chronic kidney diseae when GFR is less than ________

Answer 10

10 ml/min

Question 11

Serum creatinine and GFR have an _______ relationship

Answer 11

inverse

Question 12

What factors are sometimes used in equations calculating GFR from creatinine?

Answer 12

Age, race, gender, body surface area

Question 13

What is the Cockcroft-Gault formula?

Answer 13

Cr cl = [(140-age) x weight(kg)] / [72 x serum creatinine]

* multiply by 0.85 in women

Question 14

How is proteinuria assessed in the lab

Answer 14

Negative or positive readings for protein by urine dipstick

Question 15

What types of samples are used to quantify urine protein?

Answer 15

24 hour urine sample

“spot” urine sample (not as accurate)

Question 16

How does proteinuria lead to edema?

Answer 16

Glomerular disease → glomerular protein leak overwhelms tubular re-absorbtion → Loss of albumin → low plasma oncotic pressure → edema

Question 17

Urine protein more than 3 grams per day may cause ______ _______ with edema

Answer 17

nephrotic syndrome

Question 18

In healthy individuals there are less than _____mg of protein in a 24 hour urine sample

Answer 18

150mg

Question 19

How does proteinuria happen in the absence of kidney dysfunction?

Answer 19

Excess proteins can be produced in other parts of the body which will overwhelm the kidney’s capacity to control levels