Kidney function in sugarcane cutters in Nicaragua – A longitudinal study of workers at risk of Mesoamerican nephropathy

Chronic kidney disease is common among sugarcane workers in Central America. The main risk factor seems to be repeated high-intensity work in hot environments. Several cross-sectional studies have been performed but few longitudinal studies. The aim of the study was to examine whether kidney function changes over a few months of work during the harvest period. A group of male sugarcane cutters in Nicaragua (N=29, aged 17–38 years) was examined with renal biomarkers before and after shift on the first day at the start of harvest, on the sixth day during acclimatization, and then in mid-harvest 9 weeks later. A reference group (N=25, mainly office workers) was examined with the same biomarkers at start of harvest, and then at end of harvest 5 months later. The pre-shift renal function decreased significantly during 9 weeks of work in the cane cutters. Mean serum creatinine increased (20%), mean estimated glomerular filtration rate decreased (9%, 10mL/min), serum urea N (BUN) increased (41%), and mean urinary neutrophil gelatinase-associated lipocalin (NGAL) increased (four times). The cane cutters also developed cross-shift increases in these biomarkers, in particular serum creatinine and BUN, and in urinary uric acid. The longitudinal decrease in eGFR tended to be associated with the cross-shift increase in serum creatinine. There was a remarkable decrease of glomerular kidney function, after only 9 weeks of harvest. The cross-shift increase in serum creatinine may be caused by dehydration (pre-renal dysfunction), and when repeated on a daily basis this may cause permanently reduced GFR. •We examined sugarcane cutters at start of harvest and 9 weeks later.•Pre-shift renal function decreased substantially after 9 weeks of harvest work.•Estimated glomerular filtration rate decreased by 10mL/min.•Serum urea N (BUN) and urinary NGAL also increased substantially.•Repeated dehydration is a likely cause of long-term decrease in renal function.