The relationship between serum creatinine, serum cystatin C and glomerular filtration rate in pediatric renal transplant recipients: a pilot study.

Serum cystatin C more accurately reflects glomerular filtration rate (GFR) in pediatric renal transplant recipients than serum creatinine. Nineteen pediatric renal transplant recipients, 15 male and 4 female, ranging in age from 8.35 yr to 19.06 yr (median 13.52 yr), were enrolled in the study over an 18-month period. Twenty-eight measurements of 99mTc-DTPA GFR were compared with simultaneous measurements of serum cystatin C and Cr. Linear regression analysis, Pearson correlation coefficients and analysis of variance (anova) were used to determine the relationship between creatinine, cystatin C and GFR. The correlation coefficients (R2) for the relationship of 1/Cr to DTPA-GFR and for 1/cystatin C to DTPA-GFR were 0.63 and 0.58, respectively. There was no significant difference between serum cystatin C and serum creatinine as markers of GFR. Serum cystatin C, which costs more to measure than serum creatinine, offers no advantage in monitoring the renal function of pediatric renal transplant recipients.