Biochemical Measurements

Question 1

what is the best test of glomerular function

Answer 1

eGFR

Question 2

what is the ideal marker of GFR and the practical marker of GFR

Answer 2

Inulin

serum creatinine

Question 3

why is inulin not a practical way to monitor GFR

Answer 3

because it needs to be transfused to a constant rate in the patients blood

Question 4

what makes serum creatinine a good measure of GFR

Answer 4

it is freely filtered and does not undergo reabsorption or secretion into the renal tubule, with no extra renal elimination

Question 5

why does serum creatinine go up when GFR gets v low

Answer 5

because it is not being filtered out of the blood quickly enough so builds up

Question 6

what is a big limitation to using creatinine as a marker of GFR

Answer 6

you need to have a v significant fall in GFR for creatinine to be raised

there can be a v small rise in creatinine in response to a steep fall in GFR

could lose half of your kidney function and have creatinine barley rise

Question 7

what factors cause differences in base levels of serum creatine

Answer 7

age
sex
muscle mass
diet

Question 8

what are the chronic kidney stages based on GFR

Answer 8

G1 >90 
G2 >60 
G3a >45
G3b >30
G4 >15 
G5 <15

Question 9

what does eGFR take into account

Answer 9

creatinine serum level for patients specific age, sex, muscle mass and diet

Question 10

how can you estimate amount of proteinuria

Answer 10

24 hour urine collection

Question 11

how much proteinuria indicates significant glomerular damage

Answer 11

> 150mg/day

Question 12

how does multiple myeloma cause proteinuria

Answer 12

the over production of Ig by the malignant plasma cells is so gross it overrides the function of the glomerulus causing proteinuria

Question 13

how does proteinuria cause oedema

Answer 13

loss of protein in the urine means there is less protein in the blood

this decreases the osmolarity of the blood causing water to move out leading to oedema

Question 14

what is microalbuminuria

Answer 14

excretion of albumin in abnormal quantities but still below the protein detection of a dipstick’s

(3-300mg)

always treat to prevent progression

first sign of diabetic nephropathy

Question 15

when is urine osmolarity useful

Answer 15

to show if it is exactly the same as serum - shows tubules aren’t doing anything

or v different from serum - shows tubules are doing something