Endocrine Abstracts

Introduction: Premature ovarian insufficiency (POI) affects approximately 1% of females. In POI, hormone replacement manages symptoms and reduces the risk of bone mineral density (BMD) loss as oestrogen acts to enhance bone deposition in bone remodelling. Oestrogen may be given either as synthetic oestrogen (ethinylestradiol) as in most combined oral contraceptives (COCP), or as physiological oestrogen (oestradiol) as in hormone replacement therapy (HRT preparations) and a select few COCPs. In clinical practice patients are prescribed either the COCP or HRT; it is still unclear which of these provides optimal treatment. There is limited evidence comparing physiological vs synthetic oestrogen use in patients with POI. We investigated the BMD in females with primary and secondary POI who were taking either physiological (HRT & COCPs containing physiological oestrogen) or synthetic oestrogen therapy (COCP).

Methods: 30 females (46XX karyotype) received oestradiol (n=15) or ethinylestradiol (n=15). POI was diagnosed based on clinical amenorrhoea, raised LH and FSH levels and low oestradiol. Spine and hip BMD Z scores were obtained from DEXA scans. Z scores were chosen instead of T scores to control for age differences between groups. Mean duration of therapy was 4.7 years for ethinylestradiol and 4.0 years for oestradiol.

Results: Mean BMD at the lumbar spine was significantly greater with oestradiol (Z score -0.5±0.7) than with ethinylestradiol therapy (Z score −1.5±0.5, P<0.05, P=0.03). No significant difference was found in the BMD at the hip (P>0.05).

Discussion: These findings suggest that physiological oestrogen may have additional beneficial effects for lumbar spine density regardless of its provision in HRT or COCP forms that contain physiological oestrogen, when compared to synthetic oestrogen replacement. This may have implications when advising patients with POI on their hormone replacement.