Superiority of cystatin c to creatinine as a biomarker of kidney function: two case studies and review of the literature.

Creatinine is the most commonly used endogenous substance in the estimation of glomerular filtration rate (GFR) but it is inaccurate being influenced by body mass indices, tubular secretion and extrarenal elimination. Conversely, cystatin C is superior to creatinine as a marker of kidney function. We recently managed two children who had major risk factors for chronic kidney disease (CKD) but had serially apparently normal serum creatinine levels. However, using a cystatin C-based method, they were already in CKD stage 2. Cystatin C is a promising alternative to creatinine for routine clinical use in our setting, enabling accurate and early detection of CKD in children. Key words: cystatin C, creatinine, glomerular filtration rates.