ckd intro

Question 1

estimating kidney function?

Answer 1

Kidney function ~ Glomerular Filtration Rate •Measured using injected filtered compounds •Inulin •Cr labelled EDTA •Radiocontrast eg iohexol •Creatinine clearance (timed urine collections) –Freely filtered but 15% actively secreted (can be inhibited) •GFR ~ 100 ml/min –Declines naturally with age after ~30 (4-10ml/min/decade)

Question 2

what influences plsma creatine?

Answer 2

Plasma creatinine •Standard method for decades •Product of metabolism of creatine and phosphocreatine •Static measurement of dynamic function •Simple and cheap •Rises with falling GFR •Not linear •Non renal elimination increased in CRF •Remains in normal range until GFR < 50% •Influenced by diet “Goulash effect” •Influenced by drugs - trimethoprim •Affected by muscle mass »Age »Sex »Race

Question 3

egfr formula?

Answer 3

Cockcroft-Gault –Creatinine, weight, age, sex •MDRD (modified diet in renal disease) –Variable complexity »Creatinine, urea, age, sex, race, albumin –Simplified and agreed standard MDRD »Creatinine, age, sex, race