Serum anti-Mullerian hormone production is not correlated with seasonal fluctuations of vitamin D status in ovulatory or PCOS women

Abstract

Study question: Is there a relationship between serum anti-Mullerian hormone (AMH) levels and seasonal variations in serum vitamin D in ovulatory and polycystic ovary syndrome (PCOS) women?

Study answer: Serum AMH levels were not associated with serum vitamin D status even after controlling for relevant co-variants, with this finding being consistent for all causes of infertility. As expected, seasonal variations in serum vitamin D were observed between summer and winter.

What is known already: AMH plays an important role in maintaining ovarian reserve and modifying follicle sensitivity to FSH stimulation. Studies suggest that vitamin D has the ability to modify AMH production in vitro, yet only one clinical study reports the influence of vitamin D on AMH levels.

Study design, size, duration: This was a retrospective cohort study analyzing the potential interaction of AMH and vitamin D for 340 women (58 PCOS and 282 ovulatory women) aged less than 40 years collected as part of their routine fertility assessment between January and December 2013 at a private fertility clinic in Adelaide, South Australia.

Participants/materials, setting, methods: Patient data including age, BMI, cause of infertility, antral follicle counts (AFC), serum AMH and vitamin D levels, smoking status, and menstrual cycle length for women aged less than 40 years of age, with serum AMH and vitamin D sampled within the same 4-week period were retrieved from a database. The hours of sunlight per day and daily UV index were extracted from a database at the South Australian Bureau of Meteorology, South Australia. Serum vitamin D (25-hydroxyvitamin D) levels were analyzed against seasonal variation in sunlight and UV exposure and serum AMH levels, while controlling for relevant co-variants.

Main results and the role of chance: Seasonal variations in serum vitamin D were observed between summer and winter (30% variance; P < 0.001), while serum AMH levels (mean ± SEM) remained unaffected by season status (36.9 ± 3.3 versus 38.5 ± 2.7 pmol/l; P > 0.05), even after controlling for relevant co-variants. Overall, no correlation was observed between serum AMH and vitamin D levels, in either the PCOS or ovulatory cohort. Serum vitamin D levels were not significantly related to the underlying cause of infertility (PCOS, diminished ovarian reserve, 'fertile' ovulatory controls).

Limitations, reasons for caution: The data used to generate the study findings are cross sectional in nature. While we acknowledge that a longitudinal study monitoring the relationship between serum AMH and vitamin D in individuals over the four seasons would have been ideal, we believe the current findings are robust as our four seasonal groups did not differ for any significant co-variant for serum AMH or vitamin D (age, BMI, PCOS status or AFC) and that there is no significant association between serum vitamin D concentration and AMH production.

Wider implications of the findings: At present, while in vitro studies suggest vitamin D has the potential to modify AMH production, clinical study findings are conflicting. If vitamin D does influence AMH production, this could have important therapeutic implications.

Study funding/competing interests: K.G. was supported through a University of South Australia summer scholarship. The authors have no competing interests.

Keywords: PCOS; anti-Mullerian hormone; fertility; seasonal variation; ultra-violet light exposure; vitamin D.