Calcium homeostasis and bone density are 2 important
functions of Vitamin D in human beings. To mediate its biologic
functions, it utilizes Vitamin D receptors, that are present mostly in
calcium regulating tissues like the bone and parathyroid glands [1].
Still finding Vitamin D receptors within the reproductive tissues like
the ovary, endometrium, testis. Hypothalamus along with pituitary
has stimulated the study of Vitamin D’s role in human reproduction
[1]. Previous studies showed that Vitamin D can change the
antimullerian hormone (AMH) signaling, follicle stimulating
hormone (FSH) sensitivity and progesterone (P) Production and
release in human granulose cells as per Irani M and Merhi Z [1].
Moreover, recently Chu et al 2018 carried out a systematic review
and meta-analysis in women who were undergoing assisted
reproduction showed that women having enough Vitamin D had
>odds of getting a live birth (odds ratio 1.33) as compared to those
who had deficient Vitamin D levels [2]. Hence with the presence
of Vitamin D deficiency world over within women of reproductive
age, it is imperative to study the effect of Vitamin D deficiency on
ovarian physiology.
Based on this recent Shapiro et al. [3] conducted a retrospective
analysis from their computer data to study the relationship
of Vitamin D levels and parameters of ovarian reserve in a big
cohort of infertile women. Since they had got an academically
affiliated private fertility center where most of women presented
with diminished ovarian reserve (DOR), they studied 457 women
between 21 and 50yrs. They had baseline, Vitamin D, specifically
25hydroxy Vitamin D (25OH-D), AMH and FSH levels that had
been measured within 90days of each other. They further divided
these into 2 groups based on age (those <38yrs or>=38yrs). To
test if 25OH-D levels were predictive of AMH levels, they created
receiver operative characteristic curves, at 3 different threshold
levels -0.5ng/ml,1.0ng/ml and 5.0ng/ml. They observed that 74
women were replete while 383 women were deficient in 25OH-D,
on the bases of a <20ng/ml cutoff. Although they found comparable
25-OH-D levels in both groups. Shapiro et al found that these 25-
OH-D levels did not predict AMH in both age groups along with
all AMH cutoffs. Further, multivariate linear regression of log
transformed AMH and FSH, with 25OH-D levels that were adjusted
for confounders showed there was no correlation between 25OH-D
and the ovarian reserve parameters they had measured.
Though the authors admitted that in their data race and
ethnicity was not available and even though it is a retrospective
study this study does give important clinical data regarding Vitamin
D and ovarian reserve in a very large group of infertile women who
had high degree of DOR. This was emphasized by Shapiro et al. [3]
that this difference that they found might be since they studied a big
cohort of infertile women having DOR as compared to fertile women.
Similarly, Fabris et al. [4] carried out a retrospective study where
the studied the correlation between Vitamin D and ovarian reserve,
ovarian stimulation response along with reproductive outcome in
851 donor oocyte cycles and did not find any correlation between
Vitamin D and ovarian reserve (AMH) levels. Another retrospective
study studied this correlation between Vitamin D and ovarian
reserve in both ovulatory and PCOS patients in 340 patients, <40yrs
in Australia and did not find any correlation after accounting for
seasonal variations and Vitamin D and ovarian reserve [5]. The only
prospective study which was a cross sectional study was carried
out by Drakapoulos et al. [6] where 283 infertile women <42 yrs
undergoing first ART cycles did not find ant correlation between Vitamin D and ovarian reserve parameters like AMH an AFC. Thus,
in all these studies do indicate that there may not be a direct impact
of Vitamin D and ovarian reserve parameters. More prospective
studies are needed which study directly the role of Vitamin D and
ovarian physiology and ovarian dysfunction are still needed ,mainly
in infertile women.