Endocrine Abstracts

Context: Exogenous oestrogen administration causes prolactinoma formation in rats and there are anecdotal reports of oestrogen treatment and prolactinoma formation in gender reassignment males to females. It remains unclear whether chronic exposure to high dose oestrogen in women is linked with prolactinoma development.

Aim: The aim of this study was to determine the effect of high dose subcutaneous estrogen on prolactin and gonadotrophin levels of 101 women treated for up to 15 years following a combined hysterectomy and oophorectomy.

Patients: One hundred and one women who were receiving oestradiol implants 50–100 mg 4–6 monthly, on demand for 5–15 years following abdominal hysterectomy and bilateral salphingo-oophorectomy were studied and serum prolactin, FSH and LH levels and bone densitometry performed.

Results: One hundred and one patients received an average cumulative oestrogen dose of 1239±96.4 mg per person, 18.96±5.77 mg/kg body weight, over a period of 5 to 15 years. The trough oestradiol levels after withholding implants for 6 months were high (285.46–149.18 pg/ml (285.46–149.18 pmol/l SI unit)). Their average prolactin was 88.88±36.76 ng/ml ((88.88±36.76 mcg/l SI units)) and their FSH (1.96±1.53 IU/l) and LH (2.97±2.62 IU/l) were normal.

Conclusion: This data is reassuring that even in women exposed to very high doses of oestrogen for a prolonged period of time that prolactinoma formation is unlikely to occur: gonadotrophin levels were suppressed to the normal range whilst bone density was increased.