Heavy metal association with chronic kidney disease of unknown cause in central India-results from a case-control study

Abstract

Background: Chronic Kidney Disease of unknown cause (CKDu) a disease of exclusion, and remains unexplained in various parts of the world, including India. Previous studies have reported mixed findings about the role of heavy metals or agrochemicals in CKDu. These studies compared CKDu with healthy controls but lacked subjects with CKD as controls. The purpose of this study was to test the hypothesis whether heavy metals, i.e. Arsenic (As), Cadmium (Cd), Lead (Pb), and Chromium (Cr) are associated with CKDu, in central India. Methods: The study was conducted in a case-control manner at a tertiary care hospital. CKDu cases (n = 60) were compared with CKD (n = 62) and healthy subjects (n = 54). Blood and urine levels of As, Cd, Pb, and Cr were measured by Inductively Coupled Plasma- Optical Emission Spectrometry. Pesticide use, painkillers, smoking, and alcohol addiction were also evaluated. The median blood and urine metal levels were compared among the groups by the Kruskal-Wallis rank sum test. Results: CKDu had significantly higher pesticide and surface water usage as a source of drinking water. Blood As levels (median, IQR) were significantly higher in CKDu 91.97 (1.3–132.7) µg/L compared to CKD 4.5 (0.0–58.8) µg/L and healthy subjects 39.01 (4.8–67.4) µg/L (p < 0.001) On multinominal regression age and sex adjusted blood As was independently associated with CKDu[OR 1.013 (95%CI 1.003–1.024) P.05). Urinary Cd, Pb and Cr were undetectable in healthy subjects and were significantly higher in CKDu and CKD compared to healthy subjects (P = < 0.001). There was a significant correlation of Cd, Pb and Cr in blood and urine with each other in CKDu and CKD subjects as compared to healthy subjects. Surface water use also associated with CKDu [OR 3.178 (95%CI 1.029–9.818) p