Utilisation of gonadotrophin-releasing hormone (GnRH) analogue to differentiate ovarian from adrenal hyperandrogenism in postmenopausal women.

Postmenopausal hyperandrogenism is a relatively rare diagnosis resulting from excess androgen production from the adrenals or ovaries. The exclusion of malignant causes is a priority. Laboratory tests and imaging are utilised to help differentiate the source of excess androgens. We report two cases of postmenopausal hyperandrogenism in women aged 75 and 67 years. Both cases presented with clinical features suggestive of hyperandrogenism which had developed gradually over the previous 2 years. Laboratory investigations confirmed a significant elevation in their serum testosterone levels. In both cases, imaging did not reveal any abnormality of the adrenals or ovaries. To help differentiate an adrenal vs ovarian source a single-dose GnRH analogue was given with measurement of testosterone and gonadotrophin levels pre and post. The reduction in gonadotrophins achieved by the GnRH analogue resulted in suppression of testosterone levels which suggested an ovarian source. Both patients proceeded to bilateral oophorectomy. Histology revealed a benign hilus cell tumour in one case and a benign Leydig cell tumour in the other. Learning points: A key part of the work-up of postmenopausal hyperandrogenism is to differentiate between an adrenal or an ovarian source of excess androgens; Imaging may not identify small ovarian tumours or hyperthecosis and may also identify incidental adrenal masses which are non-functioning; Current guidelines suggest ovarian and adrenal venous sampling when imaging is inconclusive but this requires technical expertise and has a high failure rate; GnRH analogue use can successfully confirm ovarian source and should be considered as a diagnostic tool in this setting.