Cystatin C, A Better Predictor of Renal Impairment in Essential Hypertensive Patients

Due to the increased relevance of renal impairment in hypertension in developing countries like India, this study was undertaken to evaluate the serum levels of cystatin C in essential hypertensive patients. A correlation between the degree of hypertension, serum cystatin C and Glomerular Filtration Rate(GFR) was also assessed to prove the superiority of cystatin Cover creatinine to detect renal impairment at an early stage.

160 subjects were enrolled in the present study.80 hypertensive patients with 36 in stage I and 44 in stage 2 were diagnosed according to JNC VII criteria.80 age and sex matched healthy normotensive controls were included. The levels of cystatin C, urea, creatinine, uric acid, and serum electrolytes were measured.

The mean serum cystatin C in hypertensive patients(1.11±O.25 mg/l) was found to be significantly raised(p<0.0001) as compared to controls(0.82±0.12 mg/l) whereas creatinine was increased significantly only in stage II hypertensives. Also a stronger negative correlation was observed serum cystatin C and GFR when compared with creatinine and GFR. A significant positive correlation was found beween cystatin C with urea, both in stage I and stage II hypertensive patients. However a significant positive correlation was found between cystatin C and creatinine and uric acid only in stage II hypertensives.

Cystatin C shows stronger negative correlation with GFR than creatinine shows with GFR. So it can serve as more reliable and sensitive marker for identifying small changes in GFR in essential hypertensive patients.