Endocrine Abstracts

Functioning gonadotroph adenomas (FGAs) are rare pituitary tumours which express and secrete biologically active gonadotrophins or their subunits. The exact prevalence is unknown. Several syndromes have been recognised in different subgroups including hypogonadism, precocious puberty, ovarian hyperstimulation, and elevated serum testosterone with testicular enlargement. Transsphenoidal surgery is the treatment of choice and definitive diagnosis is made on subsequent histopathological assessment and immunohistochemical analysis. We present the case of a 55 year old Irish male, referred to endocrinology services following an episode of severe hypoglycaemia (serum glucose 1.1 mmol/l [3.5-7.7]). He had a history of alcohol excess, portal hypertensive gastropathy, cardiac arrest secondary to ventricular fibrillation necessitating ICD placement. He described a history of fatigue, erectile dysfunction and decreased libido. Initial investigations demonstrated a morning cortisol of 30 nmol/l (166-507) and ACTH 13.7pg/ml (7.2-63.3); discordant thyroid function with TSH 1.56 mU/l (0.27 – 4.2) and FT4 8.99 pmol/l (12 – 22); elevated FSH 14.1 IU/l (1.5 – 12.4), within range LH 2.6 IU/l (1.7 – 8.6) and low testosterone of 6.35 nmol/l (6.7-31.3). A CT pituitary revealed a 2.2cm pituitary adenoma. He was treated with hydrocortisone, levothyroxine and testosterone replacement. 1 year later he developed new visual disturbance with visual fields demonstrating a bitemporal hemianopia. He underwent transsphenoidal resection with histopathological examination demonstrating a pituitary adenoma with positive immunostaining for Chromogranin, Cam5.2, FSH, LH and SF1 consistent with a diagnosis of a gonadotroph pituitary adenoma. Post operatively his FSH had normalised to 7.3IU/l. FGAs represent a rare subset of pituitary tumours with distinct immunohistochemical profiles and varied clinical presentations. These tumours should be considered in patients with impairment in one of more pituitary axes and elevated gonadotrophins.