Serum Cystatin C level as a Marker of Early Renal Impairment in Hypertensive Patients

Abstract

Human cystatin C, a basic low molecular mass protein with 120 amino acid residues, is freely filtered by the glomerulus and almost completely reabsorbed and catabolized by the proximal tubular cells. Cystatin C has been recently proposed as a new sensitive endogenous serum marker and as a predictor for the early detection of renal impairment. This is a descriptive cross-sectional hospital based study was conducted in Khartoum North Teaching Hospital out patients clinic. This study aimed to determine the value of cystatin C in detecting early impairment of glomerular function in hypertensive patients. The study commenced in January 2008 and ended in August 2009. The study population was 176 hypertensive patients and cystatin C levels were measured by Sandwich-Enzyme-Linked Immunosorbent Assay (ELISA). Blood urea and serum creatinine were also measured by enzymatic method. The study revealed that, the cystatin C levels were found to be higher than normal in 59out of 176 (33.5%). There was a strong positive correlation between cystatin C and age (P.value=0.01). There was no gender difference in cystatin C concentrations (P.value=0.418). Moreover, cystatin C significantly increases with the duration of hypertension (P.value=0.01).In this study it was found that the majority of subjects with normal cystatin C levels were either on regular treatment or were hypertensive for short duration. On the other hand the abnormally high level of urea and creatinine were found in subjects with long term hypertension or on irregular treatment. Also high cystatin C levels were found with normal urea and creatinine levels. These finding suggest the higher sensitivity of serum cystatin C level for early renal impairment. Future research is warranted to assess cystatin C level as marker of renal impairment.