Effects of Vitamin D on Endometriosis-Related Pain: A Double-Blind Clinical Trial

Background: Endometriosis is a disabling disease of reproductive-age women. Dysmenorrhea, dyspareunia, and pelvic pain are the main symptoms of endometriosis. Its etiology is not clear. Endometriosis may have various causes, including vitamin D deficiency, but its effect is controversial. Material/Methods: In this double-blind clinical trial, we enrolled patients with endometriosis diagnosed and treated by laparoscopy, with scores of at least 3 for of dysmenorrhea and/or pelvic pain at 8 weeks after surgical treatment. They were randomly prescribed vitamin D (50 000 IU weekly for 12 weeks) or placebo. Severity of pain in the 2 groups (placebo and treatment) was compared by VAS test at 24 weeks after surgical treatment. Results: There were 19 patients in the vitamin D group and 20 in the placebo group. Baseline characteristics in the 2 groups were similar. Following the treatment with vitamin D or placebo, we did not find significant differences in severity of pelvic pain (p=0.24) and dysmenorrhea (p=0.45) between the 2 groups. Mean pelvic pain at 24 weeks after laparoscopy in the vitamin D group was 0.84 +/- 1.74 and in placebo group it was 0.68 +/- 1.70 (p=0.513). Mean dysmenorrhea was 2.10 +/- 2.33 in the vitamin D group and 2.73 +/- 2.84 in the placebo group (p=0.45). Conclusions: After ablative surgery for endometriosis, vitamin D treatment did not have a significant effect in reducing dysmenorrhea and/or pelvic pain.