The global prevalence of chronic kidney disease (CKD) of uncertain etiology may be underreported. Community-level epidemiological studies are few due to the lack of national registries and poor focus on the reporting of non-communicable diseases. Here we describe the prevalence of proteinuric-CKD and disease characteristics of three rural populations in the North Central, Central, and Southern Provinces of Sri Lanka. Patients were selected using the random cluster sampling method and those older than 19 years of age were screened for persistent dipstick proteinuria. The prevalence of proteinuric-CKD in the Medawachchiya region (North Central) was 130 of 2600 patients, 68 of 709 patients in the Yatinuwara region (Central), and 66 of 2844 patients in the Hambantota region (Southern). The mean ages of these patients with CKD ranged from 44 to 52 years. Diabetes and long-standing hypertension were the main risk factors of CKD in the Yatinuwara and Hambantota regions. Age, exceeding 60 years, and farming were strongly associated with proteinuric-CKD in the Medawachchiya region; however, major risk factors were uncertain in 87% of these patients. Of these patients, 26 underwent renal biopsy; histology indicated tubulointerstitial disease. Thus, proteinuric-CKD of uncertain etiology is prevalent in the North Central Province of Sri Lanka. In contrast, known risk factors were associated with CKD in the Central and Southern Provinces.

Background In the North Central Province of Sri Lanka, chronic kidney disease of uncertain etiology (CKDue) has increased markedly over the past 15-20 years. Methods From around 4,700 patients who were followed up, 106 affected patients who visited two local clinics in the endemic area for CKDue on August 10, 2009 and 10 pedigrees of 10 of these cases with familial clustering of CKDue participated in this study. Urine samples, collected from affected patients (n = 106), unaffected relative controls (n = 81), and Japanese controls (n = 50), were analyzed for two tubular markers: a1-microglobulin and N-acetyl-b-D-glucosaminidase. Urine samples from patients with CKDue stages 1-4 (n = 101) and all the samples from unaffected relatives and Japanese controls were analyzed for urinary cadmium concentration. Results Urinary excretion of a1-microglobulin was elevated even in the earliest stage of CKDue compared with its levels in unaffected relative controls. Urinary excretion of N-acetyl-b-D-glucosaminidase was elevated only in stage 5. In contrast, urinary cadmium excretion was similar in CKDue patients and in the unaffected relative controls, and levels in both these groups were significantly lower than the level in the Japanese controls. All levels were below the threshold level for renal toxicity, indicating the absence of any evidence of cadmium toxicity. Conclusions The present study indicates that renal tubular damage occurs in the very early stage of CKDue and demonstrates the existence of familial clustering,

This was a screening study that aimed to determine the presence of nephrotoxic mycotoxins in urine samples from patients with chronic kidney disease of uncertain etiology in the North Central Province of Sri Lanka. The percentage detection of aflatoxins, ochratoxins and fumonisins in 31 patients were 61.29%, 93.5% and 19.4%, respectively. Geometric means of urinary aflatoxins and ochratoxins were 30.93 creatinine and 34.62 ng/g creatinine in chronic kidney disease of uncertain etiology stage 1-2 patients and 84.12 ng/g creatinine and 63.52 ng/g creatinine in unaffected relatives of patients. In chronic kidney disease of uncertain etiology stage 3-5 patients, geometric means of urinary aflatoxins and ochratoxins were 10.40 and 17.08 ng/g creatinine, respectively. Non-affected relatives of patients (n = 6) had comparable levels of these mycotoxins, but healthy Japanese individuals (n = 4) had lower levels than in Sri Lanka. The higher detection rate of urinary ochratoxins in Sri Lankans indicates that exposure is common in the region.

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