Estimation of Glomerular Filtration Rate With Creatinine- Based Versus Cystatin C-Based Equations in Kidney Transplant Recipients

Introduction. Serum cystatin C is more sensitive for glomerular filtration rate (GFR) measurement, but it is not available for clinical use in all laboratories. Regarding the importance of accurate estimation of GFR in kidney transplant recipients, we compared cystatin C-based equations with creatinine-based formulas to estimate GFR as precisely and simply as possible in kidney transplant recipients. Materials and Methods. Seventy living donor kidney transplant recipients with stable kidney function were enrolled in our study. The patients’ GFRs were estimated by 3 creatinine-based equations (the modification of diet in renal disease [MDRD], abbreviated MDRD, and Cockcroft-Gault) and 5 cystatin C-based equations (Filler, Le Bricon, Rule, Hoek, and Larsson), and the results were analyzed. Results. The mean age of the recipients was 38.7 ± 13.4 years. The mean GFRs were 67.1 ± 25.9 mL/min/1.73 m2, by the Cockcroft- Gault; 61.0 ± 17.7 mL/min/1.73 m2, by the abbreviated MDRD; and 60.0 ±18.6 mL/min/1.73 m2, by the MDRD formulas. Cystatin C-based GFR estimations were 43.6 ± 16.2 mL/min/1.73 m2, 44.0 ± 13.2 mL/min/1.73 m2, 33.8 ± 14.1 mL/min/1.73 m2, 35.6 ± 13.7 mL/min/1.73 m2, and 36.9 ± 13.6 mL/min/1.73 m2 by the Filler, Le Bricon, Larsson, Rule, and Hoek equations, respectively. The estimates by creatinine-based and cystatin C-based equations were significantly different and the MDRD estimate was the closest to the cystatin C-based GFRs. Conclusions. Our findings revealed the MDRD equation could be provide a closer estimate of GFR to the cystatin C-based equations than other creatinine-based GFR calculations in kidney transplant recipients.