GFR

Question 1

What is GFR measuring exactly?

Answer 1

The volume of plasma cleared of creatinine (i.e. the volume of plasma that is filtered (per minute))

Question 2

What does raised plasma creatinine suggest?

Answer 2

Reduced elimination due to low GFR

Question 3

Calculating GFR is complicated in clinical practice as it takes up substantial time and resources.

eGFR is used instead - e standing for estimate?

What 3 other factors are used in calculating e GFR?

Answer 3

Age
Race
Sex

Question 4

Why can eGFR not be used in mild renal impairment?

Where is creatinine produced and where is it stored?

Answer 4

Plasma creatinine has a non-linear relationship with GFR and rises very little until GFR is <60.

Produced in the liver - lower in liver disease
Stored in the muscle - lower if there is reduced muscle mass (e.g bodybuilders will have very high creatinine)

Question 5

What foods if eating 12 hours before a plasma creatinine is taken, could raise creatinine levels?

Why do you have to be careful with vegetarians?

Answer 5

Meat raises levels

They have persistent low creatinine, therefore, masking kidney disease - coz they don’t eat a lot of meat