title: Heat stress, hydration and uric acid: a cross-sectional study in workers of three occupations in a hotspot of Mesoamerican nephropathy in Nicaragua.
abstract: To study Mesoamerican nephropathy (MeN) and its risk factors in three hot occupations.
  
  
  
  Cross-sectional.
  
  
  
  Chinandega and León municipalities, a MeN hotspot on the Nicaraguan Pacific coast, January-February 2013.
  
  
  
  194 male workers aged 17-39 years: 86 sugarcane cutters, 56 construction workers, 52 small-scale farmers.
  
  
  
  (1) Differences between the three occupational groups in prevalences/levels of socioeconomic, occupational, lifestyle and health risk factors for chronic kidney disease (CKD) and in biomarkers of kidney function and hydration; (2) differences in prevalences/levels of CKD risk factors between workers with reduced estimated glomerular filtration rate (eGFRCKD-EPI<80 mL/min/1.73 m2) and workers with normal kidney function (eGFRCKD-EPI≥80 mL/min/1.73 m2).
  
  
  
  Sugarcane cutters were more exposed to heat and consumed more fluid on workdays and had less obesity, lower blood sugar, lower blood pressure and a better lipid profile. Reduced eGFR occurred in 16%, 9% and 2% of sugarcane cutters, construction workers and farmers, respectively (trend cane > construction > farming, p=0.003). Significant trends (cane > construction > farming) were also observed for high serum urea nitrogen (blood urea nitrogen (BUN) >20 mg/dL), high serum creatinine (SCr >1.2 mg/dL), low urinary pH (≤5.5) and high BUN/SCr ratio (>20) but not for high urinary specific gravity (≥1.030). Sugarcane cutters also more often had proteinuria and blood and leucocytes in the urine. Workers with eGFR <80 mL/min/1.73 m2reported a higher intake of water and lower intake of sugary beverages. Serum uric acid levels related strongly and inversely to eGFR levels (adj β -10.4 mL/min/1.73 m2, 95% CI -12.2 to -8.5, p<0.001). No associations were observed for other metabolic risk factors, pesticides, non-steroidal anti-inflammatory drugs or alcohol. Among cane cutters, consumption of electrolyte hydration solution appeared preventive (adj β 8.1 mL/min/1.73 m2, p=0.09).
  
  
  
  Heat stress, dehydration and kidney dysfunction were most common among sugarcane cutters. Kidney dysfunction also occurred to a lesser extent among construction workers, but hardly at all among small-scale farmers. High serum uric acid was associated with reduced kidney function.
authors.affiliation: Unit of Occupational Medicine, Institute of Environmental Medicine (IMM), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Catharina
authors.identifier: 0000-0001-5523-9981
authors.initials: C
authors.lastname: Wesseling
authors.affiliation: Research Research Centre on Health, Work and Environment (CISTA), National Autonomous University of Nicaragua, León, Nicaragua.
authors.forename: Aurora
authors.initials: A
authors.lastname: Aragón
authors.affiliation: Research Research Centre on Health, Work and Environment (CISTA), National Autonomous University of Nicaragua, León, Nicaragua.|Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Marvin
authors.initials: M
authors.lastname: González
authors.affiliation: La Isla Foundation, Chicago, Illinois, USA.
authors.forename: Ilana
authors.initials: I
authors.lastname: Weiss
authors.affiliation: Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.|La Isla Foundation, Chicago, Illinois, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Glaser
authors.affiliation: Division of Renal Diseases and Hypertension, University of Colorado, Aurora, Colorado, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rivard
authors.affiliation: Division of Renal Diseases and Hypertension, University of Colorado, Aurora, Colorado, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Roncal-Jiménez
authors.affiliation: Department Nephrology and Mineral Metabolism, National Medical Science and Nutrition Institute Salvador Zubirán, Mexico City, Mexico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Correa-Rotter
authors.affiliation: Division of Renal Diseases and Hypertension, University of Colorado, Aurora, Colorado, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Johnson
mesh_terms: D000293:Adolescent; D000328:Adult; D000383:Agriculture; D001806:Blood Urea Nitrogen; D060389:Construction Industry; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D003681:Dehydration / Q000209:etiology*; D005919:Glomerular Filtration Rate; D018882:Heat Stress Disorders / Q000209:etiology*; D006358:Hot Temperature; D006801:Humans; D007668:Kidney / Q000473:pathology / Q000503:physiopathology; D007677:Kidney Function Tests; D008297:Male; D009527:Nicaragua; D009784:Occupational Diseases / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects*; D009790:Occupations; D051436:Renal Insufficiency, Chronic / Q000209:etiology*; D012307:Risk Factors; D014527:Uric Acid / Q000097:blood*; D055815:Young Adult
chemical_list: D014527:Uric Acid; D003404:Creatinine
keywords: EPIDEMIOLOGY; NEPHROLOGY; OCCUPATIONAL & INDUSTRIAL MEDICINE; PUBLIC HEALTH