ABSTRACT
The National Kidney Foundation (NKF), through its Kidney Disease Outcomes Quality Initiative (K/DOQI), and other National institutions proposed glomerular filtration rate (GFR) to describe, classify, screen and examine chronic kidney disease (CKD). GFR is the standard measure of renal function but cannot be practically measured for clinical and research purposes, so serum creatinine (Scr) is used to calculate estimated GFR (eGFR) which is affected by age, weight, muscle mass, race, various medications and extra-glomerular elimination. To overcome this Cystatin C (CysC) is new and reliable marker for renal function due to its low molecular weight it is freely filtered through glomerulus, completely reabsorbed and catabolized, but not secreted, by tubular cells. Various equations used for GFR estimation such as the Modification of Diet in Renal Disease (MDRD) Study equation, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Cockcroft–Gault (CG) equation based on Scr , Grubb and Hoek equation based on CysC and Stevens equation based on both SCr and CysC are used. CKD–EPI is preferred for identifying patients with CKD and for staging the disease. The risk of underestimation of kidney function with MDRD is highest when the GFR is 30 mL/minute/1.73 m2 so GFR is calculated by CKD–EPI equation for these persons. CKD–EPI is recommended for diagnosis and staging when the addition of appropriate prophylactic drugs or avoidance of certain nephrotoxic drugs should occur. The aim of this review is to evaluate from recent literature available different exogenous and endogenous markers used for the determination of GFR and which marker found suitable for the determination of GFR according to literature available on PubMed and determine their reliability in the detection and monitoring of CKD and its stages. Key words: Glomerular filtration rate, chronic kidney disease, Creatinine, Cystatin C, Measurement of GFR Abbreviations - Glomerular filtration rate (GFR), chronic kidney disease (CKD), Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Cockcroft–Gault (CG), Serum creatinine (Scr), serum cystatin C (CysC), National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative (KDOQI), Cardiovascular disease (CVD), Food and drug administration (FDA), Diethylene triamine pentaacetic acid (DTPA), Ethylene diamine tetra acetic acid (EDTA)