Vitamin D binding protein is lower in infertile patients compared to fertile controls: a case control study

• Published in: Fertility research and practice Vol. 3; no. 1; p. 14
• Main Authors: Franasiak, Jason, Shapses, Sue, Sun, Wei, Scott, Richard, Wang, Xiangbing
• Format: Journal Article
• Language: English
• Published: London BioMed Central 10.10.2017
• Subjects: Dietary supplements; Hormone replacement therapy; Infertility; Medicine; Medicine & Public Health; Obstetrics/Perinatology/Midwifery; Research Article; Vitamin D; Bioavailable vitamin D; Vitamin D binding protein; Menstrual cycle; Fertility
• ISSN: 2054-7099; 2054-7099
• DOI: 10.1186/s40738-017-0042-0

Background The importance of vitamin D in general health as well as in human reproductive success has been an area of focus. A better understanding of vitamin D metabolism, particularly vitamin D binding protein, is important when elucidating this relationship. Methods This case control trial seeks to characterize vitamin D metabolism in infertile patients undergoing natural cycle IVF as compared to normally cycling premenopausal women with proven fertility matched for age and body mass index (BMI). A total of 68 subjects were examined; 39 were infertile premenopausal women and 29 were regularly cycling fertile controls. Their 25-hydroxy vitamin D (25OHD), vitamin D binding protein (DBP), and albumin were measured and free and bioavailable 25OHD calculated. Between group comparisons were conducted with an unpaired t-test. A stepwise regression using age, BMI, 25OHD, estradiol & albumin in the model were used to determine predictors of DBP. Results Age, BMI, and total 25OHD did not differ between the two groups. However, vitamin D binding protein, free and bioavailable vitamin D were significantly different in the infertile patients as compared to the regularly cycling fertile controls ( p  < 0.01). Stepwise Regression using age, BMI, 25OHD, estradiol & albumin in the model showed that only albumin was a predictor of DBP (β-coefficient − 0.310; p  = 0.01). Conclusion The implications of lower vitamin D binding protein associated with infertility is not clear from this pilot study, and requires further study.