Serum and Urine Heavy Metal and Fluoride Levels in Patients of Chronic Kidney Disease of Unknown Etiology of Central India: A Case-Control Study

Background Although several potential risk factors for CKDu have been proposed, robust epidemiological evidence remains sparse. This study compares the levels of heavy metals and fluoride in serum and urine of patients with CKDu with the age-, sex-, and CKD stage-matched controls with CKD of known etiology. Materials and Methods This study was conducted from August 2022 to July 2023 in a tertiary care hospital in Central India. Fifty patients with CKDu and age-, sex-, and CKD stage-matched controls with CKD of known etiology between 18 to 60 years were recruited. Socio-demographic data were recorded in a structured proforma. Spot serum and urine samples were analyzed for levels of Iron (Fe), Lead (Pb), Copper (Cu), Manganese (Mn), Nickel (Ni), Cadmium (Cd), and Chromium (Cr) using Atomic Absorption Spectrophotometry (AAS). Serum and urine fluoride were measured using the ion-selective electrode method. Results Most participants were male (n=37, 74%) and >50 years (50.28±7.46 years). Among the patients, 54% (n=27) had CKD Stage V, 28% (n=14) had CKD Stage IV, and 18% (n=9) had CKD Stage III. There were no significant differences in serum or urine levels of any analyzed heavy metals between the two groups. Patients exhibited significantly higher serum fluoride compared to the control group [0.022 (0.012,0.035) mg/L vs. 0.009 (0.008,0.014) mg/dL, p < 0.001. Urine fluoride levels did not differ significantly between the two groups. Conclusion Patients with CKDu have elevated serum levels of fluoride compared to patients with CKD due to other causes.