Kidney Function, Self-Reported Symptoms, and Urine Findings in Nicaraguan Sugarcane Workers

Abstract

BackgroundAn epidemic of CKD in Central America predominantly affects males working in certain industries, including sugarcane. Urinary tract infections are commonly diagnosed among men in Nicaragua, who often receive antibiotics and nonsteroidal anti-inflammatory drugs for urinary symptoms.MethodsWe followed 251 male Nicaraguan sugarcane workers in seven job tasks over one harvest and measured urine dipstick parameters, kidney injury biomarkers, and eGFR. We administered a questionnaire about urinary symptoms, health-related behaviors, and medication history. We cultured urine in a subset of workers.ResultsThe study population was composed of factory workers (23%), cane cutters (20%), irrigators (20%), drivers (16%), agrichemical applicators (12%), seeders/reseeders (6%), and seed cutters (4%). The mean age of participants was 33.9 years, and mean employment duration was 10.1 years. Cane cutters reported higher proportions of urinary-related symptoms compared with agrichemical applicators, irrigators, and seeders/reseeders. Seed cutters were more likely to take antibiotics (22%), whereas drivers and seeders/reseeders were more likely to take pain medications (27% and 27%, respectively). Proteinuria was uncommon, whereas dipstick leukocyte esterase was relatively common, especially among cane cutters, seed cutters, and seeders/reseeders (33%, 22%, and 21% at late harvest, respectively). Dipstick leukocyte esterase at late harvest was associated with a 12.9 ml/min per 1.73 m2 (95% CI, −18.7 to −7.0) lower mean eGFR and 2.8 times (95% CI, 1.8 to 4.3) higher mean neutrophil gelatinase-associated lipocalin. In general, workers who reported urinary-related symptoms had higher mean kidney injury biomarker levels at late harvest. None of the workers had positive urine cultures, including those reporting urinary symptoms and/or with positive leukocyte esterase results. Amoxicillin, ibuprofen, and acetaminophen were the most commonly used medications.ConclusionsJob task is associated with urinary symptoms and dipstick leukocyte esterase. Urinary tract infection is misdiagnosed based on leukocyte esterase, which may be an important predictor of kidney outcomes.

Point-of-care biomarkers for prediction of kidney function trajectory among sugarcane cutters: a comparative test accuracy study

“…These findings support the hypothesis that repeated/prolonged tubular inflammation likely is a key step in CKDnt progression 4. Our results are consistent with previous reports of leukocyturia associated with SCr elevation in populations at risk of CKDnt 3 7 8. Thus, the use of dipstick monitoring in workers at risk of CKDnt could be a valuable tool for OH services.…”

“… 22 23 Furthermore, in two previous studies among workers at the same Nicaraguan mill, 0 of 114 and 0 of 70 urine cultures among male sugarcane workers were positive, although 30 and 29, respectively, of these had leukocyturia. 8 24 Dysuria (known locally as chistata ) has been considered a potential indicator of kidney injury from micro-crystalluria in some previous studies. 8 25 26 In this study, worker reports of dysuria were not associated with leukocyturia.…”

“… 8 24 Dysuria (known locally as chistata ) has been considered a potential indicator of kidney injury from micro-crystalluria in some previous studies. 8 25 26 In this study, worker reports of dysuria were not associated with leukocyturia. Whether heat stress causes leukocyturia, and whether leukocyturia is associated with a rise in kidney-specific injury biomarkers, deserve further studies.…”

“…There are previous reports of associations between leukocyturia measured using dipsticks and cross-shift SCr elevation in sugarcane workers, 7 acute kidney injury (AKI) among hospitalised sugarcane workers 3 and lower estimated glomerular filtration rate (eGFR) at end-harvest in a cross-sectional analysis. 8 …”

“…The probable link between inflammation and initiation and progression of CKDnt3 4 indicates that markers of inflammation such as leukocyturia, white blood cell count (WBC) and CRP elevation may function as early markers of CKDnt risk. There are previous reports of associations between leukocyturia measured using dipsticks and cross-shift SCr elevation in sugarcane workers,7 acute kidney injury (AKI) among hospitalised sugarcane workers3 and lower estimated glomerular filtration rate (eGFR) at end-harvest in a cross-sectional analysis 8…”