The managing of uterine leiomyomas is challenging and supplementation with the paricalcitol may be an effective, safe, and noninvasive medical treatment choice for uterine fibroids(29).
So, this study was aimed to evaluate the effect of vitamin D supplementation on the size of uterine leiomyomas in Iranian women.
Our results showed that vitamin D supplementation has significant effect on the size of leiomyomas in premenopausal women with vitamin D deficiency. In the other word, by administration of vitamin D in patients in intervention group, leiomyomas size decreased 7.14 mm. By comparing leiomyomas size between the groups (vitamin D and control), we observed significant reduction in intervention group. Also, vitamin D administration increased the 25-hydroxyvitamin D3 levels obviously.In this regard ,Halder SK et al. showed a lower serum levels of either 25-hydroxyvitamin D3 or 1,25-dihydroxyvitamin D3, related to increase the risk of symptomatic uterine fibroids( 23).
And also, in another study Halder SK et al, suggest that supplementation with the paricalcitol may be noninvasive medical treatment choice for uterine fibroids(29).
Sharan C et al. and Bla¨uer M et al. have also recently reported that, 25-dihydroxyvitamin D3 induced leiomyoma growth inhibition via catechol-Omethyl transferase in vitro (30,31) . The results of Halder SK study demonstrated that 1,25-dihydroxyvitamin D3 treatment shrinks uterine leiomyoma tumors in the Eker rat model(23 ).
Most of the study demonstrated the effect of 1, 25-dihydroxyvitamin D3 on apoptosis, modulation of several cell growth genes, protein synthesis, and cell proliferation (23, 30, 31, 32, 33). These functions are the base of anti-tumor effect of 1, 25-dihydroxyvitamin D3 on Leiomyoma.
Holder et al. in their study showed that estrogen and progesterone receptor on rat uterine myoma cells were reduced by receiving the 0.5 microgram per Kg of 1, 25-dihydroxyvitamin D3(34).
The significant role of vitamin D3 dificiency in uterine fibroid development resulted by the Soumia Brakta et al study and vitamin D3 supplement is determined an effective, safe, nonsurgical medical treatment option for a uterine fibroids 28 and Sufficient vitamin D is associated with a reduced risk of uterine fibroids (29).
The result of this study is consistent to other in- vivo and in-vitro studies which vitamin D reduces the frequency and the size of leiomyomas (14-16, 22, 23, 26- 28, 28-31, 35). Therefore, the Vitamin D administration is a low cost and estimating a yearly cost of maintenance therapy in the Vitamin D deficiency context that it is to be approximately $32 (36, 37).
The accurate mechanism for these findings needs to be further investigated to explain the mechanism of shrinking of leiomyoma tumor in human.
In conclusion, the present results showed that vitamin D administration reduces the size of uterine myoma, and no case of toxicity was observed. It seems that vitamin D administration is the effective way to treat leiomyoma.