Proteinuria

Question 1

Why can creatinine be used to estimate GFR?

Answer 1

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 2

Why do normal serum creatinine values differ between men and women?

Answer 2

men have more muscle so there is more breakdown resulting in higher normal levels of creatinine

Question 3

What are normal creatinine values?

Answer 3

In men 0.9 to 1.3 mg/dl or 79 to 114 micromol/L
In women 0.8 to 1 mg/dl or 70 to 88 micromol/L
In children 0.5 to 1 mg/dl or 0.44 to 88 micromol/L

Question 4

What happens to creatinine values in children as they grow?

Answer 4

The values gradually increase as the child gains more body mass therefore muscle mass

Question 5

Decreasing GFR by half decreases urine output by half and what happens to serum creatinine?

Answer 5

it doubles.

Question 6

Besides creatinine, what can also be used to measure GFR?

Answer 6

Inulin

Question 7

What is a normal GFR?

Answer 7

100-125 ml/min

Question 8

What are the GFR differences for the stages of chronic kidney disease?

Answer 8

stage I >90 (ml/min) >stage II >60> stage III >30> stage IV >15> stage V

Question 9

What is the relationship between GFR and serum creatinine?

Answer 9

inverse relationship

Question 10

Why do GFR calculations have such wide ranges of normal?

Answer 10

24 hour urine collections are difficult.
Blacks, men and younger adults make more creatinine than do women and older people.
Formulas try to correct for these, but not sure what is most accurate.

Question 11

Can we use formulas for sudden changes in kidney function?

Answer 11

Cannot use the formulas or rely on the absolute level of serum creatinine

Question 12

What is a urine dipstick?

Answer 12

dry chemistry perfected to react with certain substances if they are present in the urine. fairly trustworthy.

Question 13

How do we quantify urine protein?

Answer 13

can normalize the excretion of any substance in the urine to creatinine.
stop urine testing does not correspond as well as 24 hour urine collection but still works.

Question 14

What happens to protein in normal kidneys?

Answer 14

some plasma protein is filtered, several grams/day and then there is Tubular re-absorbtion, also several grams/day = balanced

Question 15

What happens to protein in diseased kidneys?

Answer 15

glomerular disease leads to protein leak that overwhelms tubular reabsorption causing loss of albumin, low plasma oncotic pressure leading to edema.

Question 16

In health, how much is the maximum urine protein?

Answer 16

maximum of 150 mg/day of which most are tubular proteins

Question 17

How much protein per day may cause nephrotic syndrome?

Answer 17

Urine protein more than 3 grams per day

Question 18

What is micro-albuminuria?

Answer 18

30 to 300 mg albumin per 24 hours or 20 to 200 microgram per minute

Question 19

Is albumin in the urine normal?

Answer 19

Nope

Question 20

Do urine dipsticks detect micro-albuminuria?

Answer 20

Nope

Question 21

What is another reason besides kidney disease you could have protein in your urine?

Answer 21

overproduction of a specific protein. very high concentrations can force protein into the urine.