Physiology of Renal Medicine

Question 1

How many litres do the kidneys filter in 24hrs?

Answer 1

180L

Question 2

How many litres of urine do healthy kidneys excrete in a day?

Answer 2

1.5-2L

Question 3

Molecules below what size are freely filtered into the nephron?

Answer 3

12,000 Da
inc:
electrolytes
sugars
amino acids
Vitamins

Question 4

What three factors affect the filtration of a molecule across the glomerular basement membrane (GBM)?

Answer 4

molecular weight

surface charge – (GBM is negatively charged
albumin = negatively charged)

hydrostatic pressure in the afferent arteriole

Question 5

What are the normal parameters of GFR?

Answer 5

100-120 mls/min/1.73m2

Question 6

What makes serum creatinine a suitable test for kidney function/

Answer 6

released by muscle

removed by kidneys

accumulates if kidney disease
not specific for site of injury
delay in rise following injury

normal range
64-104 μmol/L (male)

simple blood test

Question 7

How much kidney function is lost by the time creatinine rises above 104 umol/L ?

Answer 7

50%

Question 8

What does eGFR require?

Answer 8

Age of patient
Sex of patient
Ethnicity
Serum creatinine

Question 9

Below what eGFR do patents generally need dialysis?

Answer 9

10 mls/min/1.73m2

Question 10

What are types of insensible loss of fluid?

Answer 10

sweating
faeces
respiration

Question 11

What are some complications of having kidney disease as an acute patient?

Answer 11

Hyperkalaemia –high potassium

Acidaemia

Uraemia – accumulation of waste products
Encephalopathy
Pericarditis

Fluid imbalance

Question 12

What is the ratio of exchange for a Na+/K+ ATPase pump?

Answer 12

pumps 3Na+ out of the cell in exchange for 2K+ transferred into the cell

Question 13

What does a Na+/K+ ATPase pump do in the kidney?

Answer 13

generates a potential energy gradient across the cell wall

allows the recovery of many substances from the glomerular filtrate