A Newly Recognized Endemic Region of CKD of Undetermined Etiology (CKDu) in South India—“Tondaimandalam Nephropathy”

INTRODUCTION: Chronic kidney disease (CKD) is being increasingly recognized as a public health problem in India. The entity of CKD of undetermined etiology (CKDu) is increasingly being reported globally. Here we describe the burden of CKDu in a heretofore undescribed population in South India. METHODS: We prospectively enrolled all patients with CKD referred to the nephrology department in an observational registry. We analyzed their sociodemographic and clinical features over 4 years. The diagnosis of CKD and its etiology was determined using predefined criteria. Geolocalization of CKD patients was performed. Subsequently, CKD screening was conducted in a village located in an area of CKDu clustering. RESULTS: A total of 2424 patients were analyzed; the median age was 52 years and 75.3% were male. Seventy-five percent had advanced CKD. CKDu was the most common (51.7%) etiologic category. This is the highest proportion of CKDu reported among all published CKD studies to date from India. The clinical and demographic profile of this patient population match that of CKDu patients reported from Sri Lanka and Central America, where CKDu is endemic. A clustering of cases of CKDu was noted in specific districts using a geographic information system software. Screening of 447 people in an outreach program at a village located in an area identified to have clustering of CKDu showed a CKD prevalence of 19%. CONCLUSION: We report a previously unrecognized endemic area of CKDu among the underprivileged population engaged in agricultural labor in coastal southeastern India in the states of Tamil Nadu and Puducherry (Tondaimandalam) in India.