CYSTATIN C BASED FORMULA HAS A HIGHER DIAGNOSTIC ACCURACY THAN CREATININE BASED FORMULA IN EGYPTIAN TYPE 2 DIABETIC PATIENTS WITH EARLY NEPHROPATHY
MERVAT M. EL-ESHMAWY *
Department of Internal Medicine, Mansoura Specialized Medical Hospital, Faculty of Medicine, Mansoura University, Egypt
RASHA ELZEHERY
Department of Clinical Pathology, Faculty of Medicine, Mansoura University, Egypt
HALA SAMIR
Department of Internal Medicine, Mansoura General Hospital, Ministry of Health, Egypt
MANAL M. TARSHOBY
Department of Internal Medicine, Mansoura Specialized Medical Hospital, Faculty of Medicine, Mansoura University, Egypt
*Author to whom correspondence should be addressed.
Abstract
Background: Diabetic nephropathy is difficult to be detected by traditional methods like serum creatinine and creatinine clearance rate. Cystatin C is sensitive to changes in creatinine blind glomerular filtration rate (GFR) range (40-90 ml/min/1.73m2). The aim of this study was to assess cystatin C and to compare between cystatin C-based GFR and creatinine based GFR estimates in patients with type 2 diabetes mellitus (T2DM) either nephropathic or non-nephropathic.
Methods: The study comprised 75 patients with T2DM and 15 age- and sex-matched controls. Patients were categorized into three groups according to albuminuria status; group 1 included 25 T2DM patients with normoalbuminuria, group 2 included 25 T2DM patients with microalbuminuria and group 3 included 25 T2DM patients with macroalbuminuria or protienuria. Anthropometric measurements, cystatin C, eGFR-cystatin C, creatinine and eGFR-creatinine were assessed.
Results: Cystatin C was higher in patients with T2DM than in controls. Cystatin C was positively correlated with creatinine and urinary albumin -creatinine ratio (UACR) and negatively correlated with albumin, GFR-creatinine and GFR-cystatin. eGFR-creatinine was significantly lower in T2DM patients with macroalbuminuria than normoalbuminuria and microalbuminuria, but there was insignificant difference between patients with normoalbuminuria and microalbuminuria. eGFR-cystatin was significantly lower in T2DM patients with macroalbuminuria than in microalbuminuria and normoalbuminuria and also was significantly lower in patients with microalbuminuria than in normoalbuminuria.
Conclusion: Serum cystatin C is elevated in patients with T2DM along with progression of albuminuria. Cystatin C based formula (eGFR-cystatin C) has a higher diagnostic accuracy than that of creatinine based formula (eGFR-creatinine) in early diabetic nephropathy.
Keywords: Diabetic nephropathy, creatinine, cystatin C