Serum cystatin C concentration levels as a marker of acute renal failure in critically ill patients – A cross section study

Objective: The objective of the present study was to assess serum cystatin C concentration levels as a marker of ARF in critically ill patients. Method: This was a randomized cross sectional study done on 100 patient admitted in ICU at Basaveshwar Teaching and General Hospital (BTGH). It included the patient with normal serum creatinine who are at risk of developing failure, and excluded the patient with acute and chronic renal failure, Sr. Cystatin C and Sr. Creatinine levels were determined at admission and these were considered as the first reading of Sr. Creatinine and Sr. Cystatin C. Sr. Creatinine and Sr. Cystatin C were repeated after the patient developed ARF and was considered as second reading and results were analyzedand were compared to know which was earlier marker for acute renal failure and due consideration was given to age, gender, occupation, history, physical examination along with special attention to symptoms of the patient. Result: The present one year cross sectional study was conducted on patients admitted in the Medical Intensive Care Unit of BTGH, Gulbarga, during the period of January 2011 to May 2012.In the present study out of 100 patients, 66 (66%) were male and 34 (34%) were female. The male: female ratio was 1.94:1. In this study, out of 100 patients, there were 26 (26%) patients each in the age group of 18 to 30 years and more than 60 years. There were 36 (36%) patients each with primary gastrointestinal and respiratory disease and 12 (12%) patients with snake bite. In the present study 56 (56%) patients developed ARF. The mean age of patients with ARF was 50.25 ± 17.85 years. Themean Sr. Creatinine and Sr. Cystatin C values in ARF were 1.86 mg/dL and 3.14 mg/L respectively. The mean Sr. Creatinine and Sr. Cystatin C values in patients without ARF were 0.68 mg/dL and 0.73 mg/L respectively. In the present study among patients who developed ARF 39.29%, 53.57% and 7.14% patients have satisfied RCreat (50 to 99%), ICreat (100 to 199%) and FCreat (≥ 200%) criteria respectively. Among patients with category RCreat rise of Sr. cystatin C was ≥ 100% and 57.14% patients had 100 to 199% rise in Sr. cystatin C levels and among 42.86% patients a rise of more than or equal 200% was noted. The sensitivity, specificity, PPV, NPV of Sr.creatinine for second reading was 78.57%, 100%, 100%, 78.57% respectively and the sensitivity, specificity, PPV, NPV for second reading of Sr. Cystatin C was 100% (100%for all parameters) Sr. Creatinine was normal in some patients with ARF whereas Sr. Cystatin C was above the normal value in all ARF patients indicating that Sr. Cystatin C is more reliable marker than Sr. Creatinine. Conclusion: This study concludes that Sr. Cystatin C is early and more reliable marker of ARF than Sr. Creatinine in critically ill patients.