Serum Cystatin C A new Marker of Glomerular Filtration Rate

Kumaresan Ramanathan¹ and Giri Padmanaban²*

¹Department of Clinical Research, Periyar Maniammai University, Vallam, Thanjavur - 613 403 India.

²Consultant Nephrologist, Kidney Care, Tiruchirappalli - 620 018 India.

ABSTRACT: Background Estimation of glomerular filtration rate is widely accepted as the best overall measure of kidney function. A standard for glomerular filtration rate assessment is 99mTc – diethylene diamine tetra acetic acid renal scan. Serum creatinine has traditionally been used as a marker of estimate the glomerular filtration rate, but it is often not enough accurate. Recently serum cystatin C has been proposed as a new endogenous marker of glomerular filtration rate. Patients and Methods A total of 182 patients (46 women and 136men), who performed 99MTc – DTPA renal scan were enrolled in the present study. In each patient serum creatinine and serum cystatin C were also determined. Average age of our patients was 51.7 (from 20 to 85 years). Written consent was obtained from the patients prior to the test. Results Average isotope GFR was 33.81 ml/min / 1.73m2 (from 6 to 110 ml / min / 1.73m2). Average serum creatinine concentration was 3.6 mg /dl (from 0.8 to10 mg /dl) and average serum cystatin C concentration was 3.01 mg /l (0.8 to 8 mg /l).The correlations between isotope GFR, serum creatinine and serum cystatin C were statistically significant. The correlations between isotope GFR and serum cystatin C was better (r=-0.8848) than correlation between isotope GFR and serum creatinine (r=-0.6066). Conclusion Isotope GFR, serum creatinine and serum cystatin C are comparable markers of renal function. Based on the present study, serum cystatin C is a more reliable measure of glomerular filtration rate than serum creatinine.

KEYWORDS: Glomerular filtration rate; Kidney function; serum cystatin C; serum creatinine

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