Objective: To explore the serum vitamin D levels in perimenopausal and postmenopausal women living in Chiang Mai, Thailand, and compare the level of vitamin D between women working outdoors and indoors.

Materials and Methods: A cross-sectional study was performed. All participants resided in Chiang Mai, Thailand, and were divided into two groups by occupation characteristics. One group was women working outdoors, the other group were women working indoors. Blood collection was done in every subject for levels of vitamin D as 25-hydroxy vitamin D or 25(OH)D, BUN, creatinine, AST, ALT, calcium, and albumin.

Results: Eighty women were recruited. Two women in the indoor group were excluded due to abnormal liver enzymes (one woman) and abnormal renal function tests (one woman). Therefore, 38 women were in the indoor group and 40 women in the outdoor group. The mean serum 25(OH)D for all participants was 27.9±8.7 ng/mL, in which 29.3±8.6 ng/mL for the outdoor group and 26.4±8.6 ng/mL for the indoor group (p=0.130). The prevalence of vitamin D insufficiency based on 25(OH)D <30 ng/mL was 57.5% and 77.5% for the outdoor group and the indoor group, respectively. While the prevalence of vitamin D deficiency based on 25(OH)D <20 ng/mL was 12.5% and 25% for the outdoor group and indoor group, respectively. In which the prevalence of vitamin D insufficiency and deficiency in both groups had no statistical significance. The serum 25(OH)D of the participants who used sunscreen were lower than those who did not, with no statistical significance as 26.3±6.4 ng/mL and 29.2±10.6 ng/mL.

Conclusion: Serum vitamin D levels in perimenopausal and postmenopausal women in Chiang Mai were low and the prevalence of vitamin D insufficiency was high in both groups. There was no significant difference between women who work outdoors and indoors. Therefore, menopausal women who work outdoors are still a high-risk group for vitamin D insufficiency.

Keywords: Vitamin D; 25(OH)D; Outdoors; Indoors; Perimenopausal women; Postmenopausal women

DOI: doi.org/10.35755/jmedassocthai.2021.11.13000

Received 24 May 2021 | Revised 15 October 2021 | Accepted 18 October 2021