Exp Clin Endocrinol Diabetes 2014; 122 - P042
DOI: 10.1055/s-0034-1372059

Ovulation influences bone metabolism in women undergoing controlled ovarian stimulation

V Seifert-Klauss 1, AC Ritzinger 1, B Lesoine 2, M Kiechle 1, M Schmidmayr 1, D Berg 2
  • 1Frauenklinik der Technischen Universität München, Klinikum rechts der Isar, München, Germany
  • 22ART Bogenhausen GmbH, IVF Practice, München, Germany

Introduction: A direct effect of FSH on osteoclasts is under discussion, as ovariectomised rats experienced more bone loss than ovariectomised and also hypophysectomised rats. FSH with or without LH is used in therapeutic dosages for IVF. This study investigates whether FSH stimulates bone resorption in women undergoing gonadotropin-therapy for assisted reproduction.

Methods: Serum samples for bone markers: bone alkaline phosphatase (BAP) and osteocalcin, as well as c-terminal peptide (CTX) and tartrate- resistant acid phosphatase (TRACP) and hormonal values of women undergoing controlled oocyte stimulation were collected at T1 = second half of the preceding cycle, before GnRH analogues were used for down-regulation, T2 = beginning of the stimulation cycle with either HMG or FSH alone, T3 = oocyte retrieval day, and T4 = luteal phase of the stimulation cycle.

Results: 59 participants (mean age 38yrs, mean vitamin D3 20,5 ng/ml, mean serum calcium 2,4 mmol/l), received a long protocol treatment. At T1, 27 participants were ovulatory and 32 participants anovulatory. At T1 all bone markers were slightly lower in ovulatory cycles than in anovulatory cycles. While estrogen was comparable in both groups, initial FSH levels were significantly lower in ovulatory cycles (p = 0,002). Estrogen values at T1 and T2 were comparable in both groups and fell significantly during the observed period due to GnRH influence. No significant differences were observed in the course of BAP and osteocalcin in the ovulatory group. In this group TRACP decreased from T1 to T2 and CTX tended to rise. Osteocalcin correlated positively with FSH in the ovulatory group (p = 0,021), while TRACP (p = 0,015) and CTX (p = 0,037) correlated positively with estrogen in the anovulatory group.

Conclusions: Osteocalcin showed significant positive correlation with FSH only in the previously ovulatory group. Confounding variables such as ovulation may modify the effect of both estrogen and FSH on bone.