Early renal damage among children living in the region of highest burden of chronic kidney disease of unknown etiology (CKDu) in Sri Lanka.

BACKGROUND: Chronic kidney disease of unknown origin (CKDu) in Sri Lanka is grouped with several other epidemics of similar nature across the world as Chronic Interstitial Nephritis in Agricultural Communities (CINAC). In CKDu endemic countries, the focus has mainly been on adults. We hypothesized that studying distribution and factors associated with elevated urine albumin to creatinine ratio (UACR), an early marker of kidney injury, among children living in a CKDu endemic area may provide important clues about the onset and progression of the disease. METHODS: This cross sectional study was performed in rural primary schools in North Central Province of Sri Lnaka, a CKDu high endemic region. Total of 2880 students aging 5 to 11 years from 67 schools were enrolled for urinalysis in a random spot urine sample. Bedside Schwartz formula was used to measure estimated glomerular filtration rate (eGFR) on all children with UACR > 30 mg/g in Polonnaruwa district and a group of age matched controls. A standard multiple linear regression using log transformed UACR as the dependent variable was performed. Mean eGFR were compared between UACR elevated group and controls using independent sample t test. RESULTS: Median UACR was 10.3 mg/g. Sex, ethnicity, history of having a chronic disease and age uniquely contributed to the multiple regression model which only explained 2.8% of the variance in the log of the UACR (p < 0.001). Only 15 (0.5%) had UACR> 300 mg/g while 8.2% (n = 236) had UACR between 30 to 300 mg/g and 89.8% (n = 203) of them did not have a chronic disease (Chi square 2.21, p = 0.091). Mean eGFR was significantly lower in the group with elevated UACR (88.9 mg/dl/1.73 m2, 95% CI for mean 86.4- 91.3) compared to group with normal UACR (93.7 mg/dl/1.73 m2,95% CI 91.1- 96.3) (t 2.7, p 0.007). Three out of the four students with eGFR less than 60 mg/dl/1.73 m2 had moderately elevated UACR. CONCLUSION: This study provides evidence to suggest that children in CKDu endemic regions are having an early renal damage. This observation needs to be investigated further in order to understand the worldwide epidemic of CKDu.

Feasibility of hair sampling to assess levels of organophosphate metabolites in rural areas of Sri Lanka.

Measuring chronic pesticide exposure is important in order to investigate the associated health effects. Traditional biological samples (blood/urine) are difficult to collect, store and transport in large epidemiological studies in settings such as rural Asia. We assessed the acceptability of collecting hair samples from a rural Sri Lankan population and found that this method of data collection was feasible. We also assessed the level of non-specific metabolites (DAPS) of organophosphate pesticides in the hair samples. The median concentration (pg/mg) of each DAP was: diethyl phosphate: 83.3 (IQI 56.0, 209.4); diethyl thiophosphate: 34.7 (IQI 13.8, 147.9); diethyl dithiophosphate: 34.5 (IQI 23.4, 55.2); and dimethyl phosphate: 3 (IQI 3, 109.7). Total diethylphosphates were recovered in >80% of samples and were positively correlated with self-reported pesticide exposure.