Urinary Kidney Injury Molecule-1 as an Early Detection Biomarker for Diagnosis of Acute Kidney Injury in Patients of Snake Bite

Abstract

Introduction: Acute Kidney Injury (AKI) refers to a sudden impairment of kidney function that results in the retention of nitrogenous waste products. Acute tubular necrosis involves localised necrosis of epithelial lining in renal tubules. A soluble form of human Kidney Injury Molecule-1 (KIM-1) is a type 1 membrane-spanning protein which lends epithelial cells the capacity to perceive and phagocytose dead cells in post ischaemic kidney. Aim: To estimate urinary KIM-1 level in patients with snake bite as a potential biomarker for early detection for AKI. Materials and Methods: This was an analytical case-control study, which was conducted on 100 patients admitted for snake bite at Thanjavur Medical College and hospital, Thanjavur, Tamil Nadu, India, from January 2014 to August 2014. Patients without AKI were regarded as controls and those who developed AKI were considered as cases. Blood and urine samples were collected and analysed for urinary KIM-1 by Enzyme-Linked Immunosorbent Assay (ELISA), method, serum creatinine (by kinetic JAFFE’S method) and serum urea (by Urease- glutamate dehydrogenase method). Student’s t-test was used and p-value <0.05 was regarded significant. Pearson’s correlation coefficient was used to assess correlation between measured parameters. Results: Among 100 patients, 44 were diagnosed as patients having AKI and 56 of them did not develop AKI. No significant difference was found in urinary KIM-1 values between age group of <40 years and age group ≥40 years in cases (p-value=0.39) and in controls (p-value=0.65). A significant elevation of urinary KIM-1 was seen among cases of snake bite who developed AKI. Urinary KIM-1 levels were found to significantly rise within 24 hours of admission (p-value <0.001), whereas, serum creatinine and urea values were not increased until the day 3 of nephrotoxic trauma. The urine KIM-1 and serum creatinine on day 1 had negligible correlation (r-value=0.093, p-value=0.54) and urine KIM-1 and urea on day 1 had low positive correlation (r-value=0.380, p-value=0.011). With progressive damage to the kidneys, a positive correlation was found between urine KIM-1 and serum urea (r-value=0.864), creatinine (r-value=0.882) on third day. Also, levels of urinary KIM-1 significantly increased (p<0.001) with the severity of tubular injury. Conclusion: Urinary KIM-1 is a promising quick predictive marker of AKI in contrast to traditional markers, serum urea and creatinine.

Keywords

• acute tubular necrosis
• serum creatinine
• serum urea