Plasma Cystatin C Is Superior to 24-h Creatinine Clearance and Plasma Creatinine for Estimation of Glomerular Filtration Rate 3 Months after Kidney Transplantation

Abstract

In a recent report (1), we provided data on the early follow-up of renal function by plasma cystatin C in transplanted adults. Cystatin C was found to be an alternative and more sensitive marker of acute changes in glomerular filtration rate (GFR) than plasma creatinine, especially during acute rejection episodes. We present here some additional data on the same group of patients 3 months after surgery (n = 25; 5 patients moved to another institution). We measured GFR by the reference 51Cr-labeled EDTA clearance performed over five 30-min periods starting 1 h after injection of 50–100 μCi of 51Cr-labeled EDTA, with all individual results normalized for body surface area. Plasma cystatin C was determined by a latex particle-enhanced immunonephelometric assay (BN100; Dade-Behring) as described in detail previously (1). Plasma and urinary creatinine were measured by the Jaffe reaction on an Hitachi 747 analyzer (Boehringer); 24-h creatinine clearance was calculated from plasma and 24-h urinary creatinine. The accuracy of plasma markers to estimate GFR was calculated from the relative increases in their plasma concentrations vs their upper reference limits (creatinine, females, 100 μmol/L; males, 109 μmol/L; cystatin C, 0.94 mg/L) (1) and the relative decrease in 51Cr-labeled EDTA-measured …