Biochemical Measurements

Question 1

name two ways of expressing glomerular function

Answer 1

glomerular filtration rate

proteinuria

Question 2

what is the single best global marker of kidney function?

Answer 2

GFR

Question 3

what marker is ideal for GFR but not used due to clinical difficulties?

Answer 3

inulin

too hard to measure

Question 4

why is urea not commonly used as a marker for GFR?

Answer 4

not present at a constant rate

reabsorbed - would underestimate GFR

Question 5

what does a high urea in the blood suggest?

Answer 5

poor kidney function, as it should be excreted in the urine rather than reabsorbed

Question 6

what is the most commonly used marker for GFR?

Answer 6

creatinine

usually as urine creatinine clearance

Question 7

when is serum creatinine sensitive to changes in GFR?

Answer 7

only when GFR is quite low

Question 8

what is sensitive for changes in GFR at higher levels?

Answer 8

urine creatinine clearance

Question 9

what is urinary creatinine clearance?

Answer 9

the volume of blood that is cleared of creatinine per minute by glomerular filtration

Question 10

what three things need to be measured to calculated urinary creatinine clearance?

Answer 10

serum creatinine
urine creatinine
volume of urine

Question 11

what is the calculation for the urinary creatinine clearance?

Answer 11

[creatinine]urine x urine volume
OVER
[creatinine]serum x duration of collection

Question 12

what does a high urinary creatinine clearance suggest in terms of GFR?

Answer 12

higher GFR

shows that more clearance has occurred and that the kidneys are working well

Question 13

what is eGFR?

Answer 13

estimated GFR

Question 14

what can lead to proteinuria?

Answer 14

the glomeruli can be leaky in disease and let proteins through

Question 15

how can the amount of protein in urine be estimated?

Answer 15

by doing a 24 hour collection

Question 16

what does the protein/creatinine ratio provide information on?

Answer 16

how concentrated or dilute someone’s urine is

Question 17

what protein level in the urine suggests significant glomerular damage?

Answer 17

> 150mg/day

Question 18

name two types of proteinuria

Answer 18

overflow

glomerular

Question 19

name a disease that causes overflow proteinuria

Answer 19

multiple myeloma

Question 20

what happens in overflow proteinuria?

Answer 20

there is a gross overproduction of protein that overwhelms the glomeruli

Question 21

what happens in glomerular proteinuria?

Answer 21

pathology stops the glomeruli from working properly

Question 22

name a disease that cause glomerular proteinuria

Answer 22

nephrotic syndrome

Question 23

what does PCR stand for?

Answer 23

protein creatinine ratio

Question 24

what does ACR stand for?

Answer 24

albumin creatinine ratio

Question 25

what does microalbuminuria refer ro?

Answer 25

the excretion of albumin in abnormal quantities, but still below the limit of detection by a dipstick

Question 26

what is the earliest expression of diabetic nephropathy?

Answer 26

microalbuminuria

Question 27

if a diabetic patient has microalbuminuria, what should be prescribed?

Answer 27

an ACE inhibitor

Question 28

how do you assess tubular function?

Answer 28

measure serum and urine osmolalities

Question 29

what will be serum and urine osmolalities be like if the tubules are functioning?

Answer 29

values will be very different between the two