PT Journal AU Daugaard, S Garde, AH Hansen, ÃM Vistisen, HT Rejnmark, L Kolstad, HA TI Indoor, outdoor, and night work and blood concentrations of vitamin D and parathyroid hormone SO Scandinavian Journal of Work, Environment & Health PD 11VL PY 2018 BP 647 EP 657 IS 6 DI 10.5271/sjweh.3745 WP https://www.sjweh.fi/show_abstract.php?abstract_id=3745 DE blood concentration; cross-sectional study; diet; indoor work; night work; occupation; occupational health; outdoor work; parathyroid hormone; risk factor; season; shift work; ultraviolet radiation; vitamin D SN 0355-3140 AB '

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OBJECTIVES ': 'The aim of this study was to examine blood concentrations of 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) among indoor, outdoor, permanent and rotating night workers and the association with hours spent outdoors on and off work days.

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METHODS ': 'Blood samples were collected from 425 workers (162 indoor, 112 outdoor, 118 rotating night and 33 permanent night workers) throughout all seasons. Serum concentrations of 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) were analyzed by isotope dilution liquid chromatography-tandem mass spectrometry (LC MS/MS) and an automated immune analyzer, respectively. Personal light exposure levels were continuously recorded and used to estimate hours spent outdoors (all workers).

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RESULTS ': 'Permanent night workers had 25.3% (95% CI 11.9–36.6) lower 25OHD concentration, 4.55 (95% CI 1.39–14.94) higher odds of vitamin D insufficiency (<50 nmol/L) and 14.5% [95% confidence interval (CI) 0.1–31.1] higher PTH concentration than indoor workers. Outdoor workers had similar 25OHD concentrations but 7.5% (95% CI -0.5–14.9) lower PTH concentration compared to indoor workers. Rotating night workers 25OHD and PTH concentrations did not differ from indoor workers. Concentration of 25OHD increased by 5.2% (95% CI 1.1–9.5) per hour spent outdoor at workdays in the summer.

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CONCLUSION ': 'Clinicians should be aware that vitamin D insufficiency may be more prevalent among permanent night workers and human resources should consider the positive effect of allowing workers to spend time outdoor during work hours.

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