Glomerular filtration rate determination by creatinine and cystatin-C in patients with acute pyelonephritis

Measurement of glomerular filtration rate (GFR) and monitoring of it in any patient on nephrotoxic drugs is very important. Recently, cystatin C (cys-C) has been introduced as a better marker for determining and monitoring renal function than creatinine especially in a mild decrease of GFR. This study was done to assess the change of GFR measurement based on serum Cys-C and creatinine and their comparison in children with acute pyelonephritis on amikacin.

All children with acute pyelonephritis who were admitted in Nephrology ward were enrolled in this study. Serum creatinine, serum cys-C and the GFR calculation based on them were measured in patients on the day of admission (day zero) and then on days 3 and 7 after the start of treatment with amikacin and p-value less than 0.05 was considered significant.

Among the 70 children, 61 patients were females and the others were males. Mean age was 42.66±41.53 months. Estimated GFR based on creatinine on day 0 (before amikacin administration), 3 and 7 were 72.41±20.89 ml/min/1.73 m2, 78.42±21.15 ml/min/1.73 m2 and 80.5±22.43 ml/min/1.73 m2, respectively. Moreover, GFR based on cys-C during these days were 116.23±58.9 ml/min/1.73 m2, 116.49±53.31 ml/min/1.73 m2 and 108.37±51.02 ml/min/1.73 m2, respectively (p<0.05).

According to this study, decrease of GFR calculation based on Cys-C was seen and estimated GFR was not changed according to creatinine. So, we recommend the use of cys-C for the monitoring of renal function in any patient treated with nephrotoxic drugs such as amikacin.