STUDY OF SERUM CYSTATIN C & CREATININE AS A RELIABLE MARKER FOR DIAGNOSIS OF IMPAIRED RENAL FUNCTION IN HYPERTENSIVE PATIENTS

In the past serum creatinine concentration was used as one of the important markers for early detection of kidney disorders, however recent studies suggest serum cystatin C to be a better marker. Therefore in this study we compared the diagnostic value of cystatin C with serum creatinine to evaluate kidney function in patients with high blood pressure. Materials & Methods: This clinical trial study was conducted on high blood pressure patients referring to Mehrad hospital during 1387-1389 for checking their kidney function. Cobasmira automated analyzer was used to determine serum creatinine. The serum cystatin C was measured using ELISA method. The glomerular filtration rate was determined by measuring 24hr creatinine clearance. Positive and negative predictive value, sensitivity and specificity of cystatin C and creatinine were determined. Results: We studied 35 patients with high blood pressure (20 men and 15 women mean age, 49±11). This research work showed that positive predictive value and negative predictive value of creatinine were 94.3% and 31% respectively. And for cystatin C, were 92.3% and 44% respectively. The false positive and negative result for serum creatinine method were 2.8% and 31.4% and for cystatin C were 5.7% and 14.2% respectively. Total accuracy of cystatin C was 90% and creatinine was 65.8%. Finally based on results obtained from this study cystatin C had a sensitivity of 82 % and specificity of 57% and serum creatinine had sensitivity of 62 % and specificity of 41% for detecting crcl<78 ml/min/1.73m2. Conclusion: It seems that measurement of serum cystatin C can be applied to detect the reduction of kidney function in the primary stages of kidney disorder.