32.5 - SDL Renal Tests

Question 1

What is 1,25 dihydroxycholecalciferol associated with?

Answer 1

Calcium homeostasis

Question 2

What is 1,25 dihydroxycholecalciferol associated with?

Answer 2

Calcium homeostasis

Question 3

Normal urine output

Answer 3

750-2000ml / 24hr

Question 4

Oliguria

Question 5

Anuria

Question 6

Polyuria

Answer 6

> 3000ml/24hrs

Question 7

Plasma urea test

Answer 7

Quick
3-8mmol/l
Sensitive but non-specific

Question 8

Factors which affect plasma urea

Answer 8

GIT protein and tissue protein are turned into liver amino acids which go into plasma urea

Kidney filtration

Kidney reabsorption

Distribution vol

Question 9

Urea excretion

Answer 9

40% is reabsorbed by renal tubules

More urea reabsorbed if rate of tubular flow is low

Question 10

Cause of slow tubular flow

Answer 10

Renal hypoperfusion

Question 11

What causes renal hypoperfusion

Answer 11

MI
Fluid loss
Circulatory insufficiency
Renal artery stenosis

Question 12

Plasma creatinine

Answer 12

50-140 umol/l
Increase in conc as GFR decreases
Analytical intererences inc. acetoacetate which is in the urine of those with ketoacidosis, jaundice and infection also increase output
Change in patient more important than the value

NOT proportional to renal damage

Question 13

Plasma creatinine

Answer 13

50-140 umol/l

Increase in conc as GFR decreases

Question 14

Normal urine output

Answer 14

750-2000ml / 24hr

Question 15

Oliguria

Question 16

Anuria

Question 17

Polyuria

Answer 17

> 3000ml/24hrs

Question 18

Is creatinine clearance a good measurement?

Answer 18

Not reliable

Secretion is inhibited by common drugs e.g. aspirin and cimetidine

Question 19

Factors which affect plasma urea

Answer 19

GIT protein and tissue protein are turned into liver amino acids which go into plasma urea

Kidney filtration

Kidney reabsorption

Distribution vol

Question 20

Urea excretion

Answer 20

40% is reabsorbed by renal tubules

More urea reabsorbed if rate of tubular flow is low

Question 21

Cause of slow tubular flow

Answer 21

Renal hypoperfusion

Question 22

What causes renal hypoperfusion

Answer 22

MI
Fluid loss
Circulatory insufficiency
Renal artery stenosis

Question 23

What causes increased plasma urea

Answer 23

GI bleed
Trauma
Renal hypoperfusion

Acute renal impairment
Chronic renal disease

Post-renal obstruction - calculus tumour

Note this are in prerenal, renal and postrenal

Question 24

Plasma creatinine

Answer 24

50-140 umol/l

Increase in conc as GFR decreases

Question 25

How does plasma creatinine increase relative to renal problems?

Answer 25

Exponentially

Question 26

GFR measuring

Answer 26

Seldom measured in clinical practice Reserved for kidney donors or dose of certain drugs (chemotherapy) Involves measuring outflow of radioactive substance

Question 27

What is therefore used as a measurement instead of GFR?

Answer 27

Creatinine clearance

Question 28

How to calculate creatinine clearance

Answer 28

Creatinine clearance = ([urine creatinine mmol/l] x urine volume ml) divided by [plasma creatinine umol/l] note plasma creatinine is umol/l

Question 29

Which is higher value: creatinine clearance vs GFR

Answer 29

Creatinine Clearance by 10-30%

Question 30

Is creatinine clearance a good measurement?

Answer 30

Not reliable | Secretion is inhibited by common drugs e.g. aspirin and cimetidine

Question 31

Creatinine clearance and affect on plasma - 60-120ml/min

Answer 31

None

Question 32

Creatinine clearance and affect on plasma - 30-60 ml/min

Answer 32

increased creatinine | increased urea

Question 33

Creatinine clearance and affect on plasma - 20-30 ml/min

Answer 33

increased potassium | decreased bicarbonate

Question 34

Creatinine clearance and affect on plasma - 10-20 ml/min

Answer 34

increased phosphate | increased uric acid

Question 35

eGFR is used in common practice - stages and eGFR value

Answer 35

``` 1 - 90+ 2 - 60-89 3a - 45-59 3b - 30-44 4 - 15-29 5 - ```