Renal Function in Rural India: Influence of Age, Body Mass Index, and Biochemical Parameters

Abstract

Background: Renal function is a critical marker of systemic health, influenced by both physiological aging and metabolic stress. However, limited data exist on how demographic and biochemical variables jointly impact kidney function in rural Indian populations. Aim: To assess the influence of age, body mass index (BMI), and key biochemical indices on renal function within a rural Indian cohort. Methods: A cross-sectional study of 200 individuals was conducted, analysing estimated glomerular filtration rate (eGFR), serum creatinine, and blood urea nitrogen (BUN) across age groups. Pearson’s correlation and multivariate linear regression were used to explore associations between renal function and demographic/biochemical predictors. Results: The mean age was 59.7 ± 17.2 years, and mean BMI was 24.5 ± 4.2 kg/m². A significant age-dependent decline in GFR was observed: from 131.2 mL/min in individuals <40 years to 62.1 mL/min in those >60 years. Strong negative correlations were found between age and GFR (r = -0.71, p < 0.001) and between BMI and GFR (r = -0.35, p = 0.002), while BMI positively correlated with serum creatinine (r = 0.29, p = 0.006). Age also showed a strong positive correlation with BUN (r = 0.64, p < 0.001). In multivariate analysis, age (β = -0.56, p < 0.001), BMI (β = -0.28, p = 0.004), and bicarbonate levels (β = +0.31, p = 0.002) independently predicted GFR. Conclusion: Age and BMI are strong, independent predictors of renal function decline in rural populations. Elevated bicarbonate levels appear to exert a protective effect. These findings underscore the need for age- and weight-adjusted screening protocols in low-resource settings to enable earlier intervention.