Biochemical Investigations

Question 1

Plasma proteins should be __________ so proteinuria suggests _________

Answer 1

retained

glomerular damage

Question 2

What is an early sign of glomerular damage?

Answer 2

Microalbuminuria (small amounts of albumin in the urine)

Question 3

Describe diabetic screening for kidney damage?

Answer 3

Microalbuminuria is earliest sign but is not detectable on a standard urine dipstick so need to measure protein: creatinine ratio and albumin: creatinine ratio. Ratio increased in damage.

Question 4

What tests for tubular function testing?

Answer 4

Urine osmolality vs serum osmolality
If serum and urine osmolarity are similar that suggests the kidneys aren’t doing much to concentrate urine so may be renal tubule damage

Question 5

What is creatinine?

Answer 5

a waste product from the normal breakdown of muscle tissue. As creatinine is produced, it’s filtered through the kidneys and excreted in urine.

Question 6

ACR or PCR is more sensitive at detecting low levels or proteinuria?

Answer 6

ACR

Question 7

What is eGFR?

Answer 7

Serum creatinine GFR basically with correction for age, sex and ethnicity
eGFR is usually given alongside every GFR

Question 8

Limitation of serum creatinine measurements?

Answer 8

exponential relationship so GFR can 1/2 and won’t get much change in creatinine isn’t sensitive to changes in GFR until GFR is quite low

Question 9

In practice how is GFR measured?

Answer 9

Serum creatinine GFR
eGFR
If need really accurate will do inulin or CrEDTA clearance
Urine creatinine clearance is largely historic

Question 10

eGFR is not accurate at higher values so is only reported if lower than ____

Answer 10

60 ml/min

Question 11

When do you want to know about tubular function and why?

Answer 11

In oliguria

If tubule function is normal that may suggest a pre or post renal cause of oliguria