Blood tests

Question 1

GFR definition

Answer 1

volume of plasma filtered by glomeruli in 1 minute measured in min/ml

Question 2

characteristics substance gfr measurement

Answer 2

any substance filtered but not actively secreted or reabsorbed by tubules

Question 3

substances used for GFR measurement

Answer 3

inulin is ideal GFR marker

Question 4

GFR and body surface area

Answer 4

proportional to BSA expressed as ml/min/1.73m2 = this being average adult BSA

Question 5

CKD parameters

Answer 5

1= >90
2 = >60
3= 30-60
4 = 15-30
5 = <15

Question 6

use of creatinine to calculate GFR

Answer 6

can be used as surrogate marker i.e. endogenous marker
primarily filtered at glomerulus
production relatively stable
tends to over estimate when GFR is normal as 10% secreted by tubules
also affected by muscle mass

Question 7

accuracy creatinine as rises

Answer 7

GFR calculation less accurate as creatinine rises

Question 8

calculations GFR

Answer 8

cockcroft gault formula - age body mass serum creat

MDRD formula - age gender, creainine afro carribean ethnicity