Assessment of Urine Kidney Injury Molecule-1 as an Early Biomarker for Nephropathy in Sickle Cell Anaemia Patients

Background: Sickle cell anemia (SCA), a form of sickle cell disorder (SCD), is characterized by chronic hemolytic anemia, recurrent acute and persistent pain episodes, and progressive multiorgan complications. Among these, sickle cell nephropathy (SCN) is a significant and severe complication that may advance to chronic kidney disease (CKD), often beginning asymptomatically in childhood. Despite its clinical relevance, data on the early assessment of renal function in patients with SCA remain limited in Nigeria, hindering timely detection and intervention. This study, therefore, investigates the diagnostic utility of urinary kidney injury molecule-1 (KIM-1) as a biomarker for renal dysfunction in patients with steady-state SCA. Objective: This study assessed urinary kidney injury molecule 1 as an early biomarker of nephropathy in patients with sickle cell anemia. Method: This cross-sectional comparative study included ninety participants, comprising forty-five individuals with a normal hemoglobin genotype (HbAA) and forty-five with sickle cell anemia (HbSS). Hemoglobin genotype was determined using cellulose acetate electrophoresis. Serum creatinine levels were measured using the modified Jaffe method, and the estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Urinary kidney injury molecule-1 (KIM-1) concentrations were assessed using the enzyme-linked immunosorbent assay (ELISA) technique. Results: This study observed no significant difference in mean age between the HbAA and HbSS groups (14.16 ± 2.54 vs. 13.52 ± 3.33 years; p = 0.121). However, the mean body mass index (BMI) was significantly higher in the HbAA group (21.40 ± 1.02 kg/m²) compared to the HbSS group (18.69 ± 2.19 kg/m²; p = 0.004). Serum creatinine levels did not differ significantly between the two groups (p = 0.311). In contrast, urinary KIM-1 levels were significantly elevated in the HbSS group relative to the HbAA group (p < 0.001). In addition, a significant negative correlation was observed between urinary KIM-1 and estimated glomerular filtration rate (eGFR) in both groups, with the correlation being stronger in the HbSS group (HbAA: r = –0.64, p = 0.005; HbSS: r = –0.79, p = 0.002). Conclusion: The findings from this study observed no significant difference in serum creatinine levels between individuals with HbAA and HbSS genotypes. However, urinary KIM-1 concentrations were significantly higher in the HbSS group, with a stronger negative correlation with eGFR. These findings suggest that, while serum creatinine may not be effective in detecting early renal impairment in sickle cell anemia, urinary KIM-1 has promising potential for detecting renal dysfunction in this population.