Introduction Shiftwork that disrupts circadian rhythms has been classified as probable carcinogenic to humans by IARC (2007). Among possible mechanisms of this effect, the modification of hormone homeostasis has been advocated. Aim of the present study was to evaluate the influence of night-shift work on the levels of steroid hormones, melatonin, and serum vitamin D in hospital female nurses.
Methods Ninety-five female hospital nurses were recruited: 45 performing ‘1–1–1’ fast rotating shift schedule on 5 day cycle (morning – afternoon – night – rest – rest) and 50 working only on dayshift, as controls. Specimens were collected to measure 13 serum steroid hormones, salivary cortisol, cortisone and melatonin in morning and evening samples, and serum vitamin D. All markers were assayed by liquid chromatography coupled with triple quadrupole mass spectrometry.
Results Comparing fast rotating and day shift nurses, significant differences were found in the levels of steroid hormones. Multiple linear regression analysis, considering hormones or vitamin D as dependent variable and work-shift type as independent variable, showed no differences between the two group as concerns the levels of stress hormones, whereas a significant increase of corticosterone and a marginal decrease of vitamin D were observed in fast rotating shift nurses, after adjusting for age, body mass index, tobacco smoking, and sampling time.
Conclusion This work shows that the a rapid rotating shiftwork schedule ‘1–1–1’ does not modify the global steroid hormone homeostasis; however, further work is needed to investigate the meaning of the observed increase of corticosterone levels.
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