BANTAO Journal 2014; 12(1):33-35 DOI: 10.2478/bj-2014-0007    ________________________ Correspondence to: Mitra Mahdavi-Mazdeh, Iranian Tissue Bank&Research Center, Imam Khomeini Hospital, Keshavarz lv. Tehran, Iran; E-mail: mmahdavi@tums.ac.ir BJ %$17$2-RXUQDO Original Article Cystatin C versus creatinine-based GFR formula in CKD patients Zahra Abrishami 1 , Mitra Mahdavi-Mazdeh 2,3 , Farzanehsadat Minoo 3 and Monireh Amerian 4 1 Internal Medicine Department, 2 Iranian Tissue Bank &Research Center, 3 Nephrology Research Center, Tehran University of Medical Sciences, 4 Shahrood University of Medical Sciences, Tehran, Iran Abstract Introduction. Glomerular Filtration Rate (GFR) is the main tool to assess kidney function. Some experts suggest cystatin C as a more precise and accurate indicator than creatinine to calculate GFR. This study is designed to assess if cystatin C is more helpful in early diagnosis and better follow-up of Chronic Kidney Disease (CKD) patients who may benefit more from appropriate and timely management. Methods. We studied 312 patients in different stages of CKD and normal kidney function as control. GFR based on creatinine (Jaffe and enzymatic) and cystatin C were calculated and compared. Results. A total of 146(46.8%) patients were male with a mean age of 53±17.5 years. The patients were divided into 3 groups based on GFR (>60 cc/min/1.73m 2 , 30< GFR<60cc/min/1.73m 2 , 15<GFR<30cc/min/1.73m 2 ). No significant differences in GFR estimation based on creatinine and cystatin C were found. Conclusions. There were no significant differences bet- ween serum cystatin C-based formula and creatinine- based formula for GFR calculation. Therefore, they can be used interchangeably. Key words: chronic kidney disease, estimated glomerular filtration rate, cystatin C, creatinine ___________________________________________ Introduction Chronic Kidney Disease (CKD) can occur due to diffe- rent acute or chronic disease conditions. It can occur due to hypotensive attacks in patients undergoing chronic processes such as hypertension and diabetes mellitus [1]. The huge cost of renal replacement therapy (RRT) for health community system is the main reason that health care providers are keen on early detection prog- rams of CKD [2]. Therefore, any more reliable tool than creatinine to assess kidney function, estimated glomerular filtration rate (GFR), to find CKD at an earlier stage to post- pone end-stage renal disease and RRT is welcomed [3,4]. GFR is estimated routinely by different creatinine-based formulas like Cockroft-gault (CG) and modification of diet in renal disease (MDRD). Furthermore, other mole- cules like uthalamate and inulin have been introduced for GFR calculation. However, they have limited popu- larity because of the expensive and time-consuming process. Recently, serum cystatin C (s-CysC) has been suggested as a more reliable marker than serum creati- nine to evaluate GFR [5-7]. Cystatin C is a cystein proteinase inhibitor that is con- stantly synthesized by all nucleated cells. It can be freely filtrated through glomerulus and then be absorbed with- out secretion [6,8,9]. There are some unrelated condi- tions to renal function that may cause serum cystatin C to rise, such as malignancy, thyroid disease, preg- nancy and chronic infection [10]. Hejes, et al. found that-CysC-based GFR to be more accurate than crea- tinine-based GFR in patients with GFR <60cc/min/1.73m2 [11]. It is well-known that serum creatinine level is affected by muscle mass, catabolic state, age, gender, diet and medications. Some researchers believe that cystatin C is a better parameter than creatinine for GFR estimation [5,6]. This study was designed to assess the correlation of crea- tinine-based formula and s-CysC-based formula of GFR calculation in different stages of kidney function and to see if it has a significant impact on timely CKD diagnosis. Material and methods The study included patients who were admitted in the Nephrology Ward or the Clinic for CKD management and to other wards or clinics in Imam Khomeini Hospital Com- plex. They had normal creatinine in 2013 and were conse- cutively visited and enrolled in the study if they did not have thyroid disease, current infection and malignancy. Blood samples were collected in order to determine creatinine (Jaffe), creatinine (enzymatic), cystatin C (en- zymatic), cholesterol (CHOD Manner with autoanaly- zer), triglyceride (PAP manner with auto analyzer), al- bumin (BCG manner with autoanalyzer), hemoglobin and blood glucose.