Biomarkers of Kidney Injury Among Nicaraguan Sugarcane Workers

Background In Central America, an epidemic of chronic kidney disease of unknown cause disproportionately affects young male agricultural workers. Study Design Longitudinal cohort study. Setting & Participants 284 sugarcane workers in 7 jobs were recruited from one company in northwestern Nicaragua. Blood and urine samples were collected before and near the end of the 6-month harvest season. Predictors Job category (cane cutter, seeder, seed cutter, agrichemical applicator, irrigator, driver, and factory worker); self-reported water and electrolyte solution intake. Outcomes & Measurements Changes in levels of urinary kidney injury biomarkers normalized to urine creatinine level, including neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), N -acetyl-β-d-glucosaminidase (NAG), and albumin; serum creatinine–based estimated glomerular filtration rate (eGFR). Results Mean eGFR was 113 mL/min/1.73 m 2 and  2 , respectively. Limitations Surrogate exposure measure, loss to follow-up. Conclusions Results are consistent with the hypothesis that occupational heat stress and volume depletion may be associated with the development of kidney disease, and future studies should directly measure these occupational factors. The presence of urine tubular injury markers supports a tubulointerstitial disease that could occur with repeated tubular injury.