Serum Cystatin-C as a Pre-emptive Indicator of Renal Impairment in Patients with Sickle Cell Disease: A Cross-sectional Study

Introduction: Sickle Cell Disease (SCD) is a chronic haemoglobinopathy frequently associated with renal complications that progress silently and contribute significantly to morbidity and mortality. Conventional renal biomarkers such as serum creatinine and urea often rise only after substantial nephron loss has occurred. Serum cystatin-C, an endogenous cysteine protease inhibitor, has emerged as a promising early biomarker of renal dysfunction, independent of age, sex, and muscle mass. Aim: To estimate serum cystatin-C level and renal function tests in adult SCD patients and to analyse their correlation with conventional renal parameters. Materials and Methods: A cross-sectional study was conducted at the Department of Biochemistry, Dhiraj General Hospital and Smt. Bhikhiben Kanjibhai Shah Medical Institute and Research Centre, Piparia, Vadodara, Gujarat, India, over a period of one year from January 2023 to December 2023. A total of 204 adult male and female SCD patients were enrolled. Patients with known renal disease, renal surgery, or on nephrotoxic medications were excluded. Serum cystatin-C was estimated using Enzyme-Linked Immunosorbent Assay (ELISA), while serum urea, creatinine, uric acid, protein, albumin, and electrolytes were measured using a fully automated biochemistry analyser (EM-200). Data were analysed with Statistical Package for Social Sciences (SPSS) version 25.0 software, and analysis was performed to assess Pearson’s correlation coefficients, p-value <0.05 was considered statistically significant. Results: The current study evaluated 204 patients with SCD (83 males and 121 females), with a mean age of 21.59±3.61 years. Among this group, 23 patients (11.3%) were identified as having renal dysfunction. Patients with renal dysfunction demonstrated significantly elevated serum urea (72.5±51.9 vs. 24.7±8.02 mg/dL, p-value <0.001), creatinine (2.13±1.5 vs. 0.67±0.12 mg/dL, p-value <0.001), and uric acid, along with reduced serum protein and albumin compared to those without dysfunction. Electrolyte disturbances elevated sodium (135- 145 mEq/L) K+(3.5-5.0 mEq/L), Cl-(90-110 mEq/L) were also noted. Serum cystatin-C showed a strong positive correlation with serum urea (r-value=0.7034, p-value <0.001) and creatinine (r-value=0.8031, p-value <0.001), highlighting its sensitivity in detecting renal impairment. A p-value <0.05 was considered statistically significant. Conclusion: Serum cystatin-C is a valuable early biomarker of renal dysfunction in SCD patients, showing stronger correlation with renal impairment than conventional markers. Routine incorporation of cystatin-C testing may enable timely diagnosis, monitoring, and prevention of progression to Chronic Kidney Disease (CKD) in this high-risk group.