Correlation of Kidney Injury Molecule-1 and Renal Lipotoxicity among Adult Obese Individuals with Asymptomatic Kidney Function

Abstract

BACKGROUND: Obesity is a chronic metabolic condition characterised by excessive fat deposition with deleterious effects on human health. Obesity can adversely affect renal function by causing defective lipid build-up and increased deposition of fat in the renal sinus. AIMS: The aim of this study was to establish the relationship between serum Kidney Injury Molecule-1 (KIM-1) concentration and renal lipotoxicity, using serum free fatty acid (FFA) level as its surrogate marker, among asymptomatic adult obese individuals. METHODS: A cross-sectional study of adult obese outpatients in the University of Nigeria Teaching Hospital, without signs and symptoms of kidney damage, assessed for levels of serum KIM-1 and FFA, as well as anthropometry parameters and other markers of renal damage. Non-parametric tests were used for variables that were not normally distributed. ρ <0.05 was statistically significant. RESULTS: Two hundred and twenty-seven participants with a mean age of 40 ± 11 years were recruited, of whom 112 were obese subjects and 115 non-obese controls. The median (interquartile range) serum KIM-1 level among the obese participants (545.7 [469.3-608.2 pg/mL]) was significantly lower than that of the non-obese controls (672.6 [579.8-807.4 pg/mL]) (ρ <0.01), even though FFA was not significantly different between the two groups (ρ = 0.991). Among the obese subjects, there was a positive correlation between serum KIM-1 and FFA (r = 0.232, ρ = 0.014), but a negative correlation with waist circumference (WC) (r = -0.236, ρ = 0.013) and waist-to-hip ratio (WHR) (r = -0.315, ρ = 0.001) which were statistically significant. CONCLUSION: Serum KIM-1 levels were lower in the obese subjects than in the non-obese controls, even though there was no difference in serum FFA levels among the two groups. The obese group showed an inverse relationship of serum KIM-1 with WC and WHR, respectively.