Indoor, outdoor, and night work and blood concentrations of vitamin D and parathyroid hormone

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. 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). 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 (by Daugaard S, Garde AH, Hansen ÅM, Vistisen HT, Rejnmark L, Kolstad HA. doi:10.5271/sjweh.3743

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