Endocrine Abstracts

A 19 year old male was referred urgently due to a significantly raised Prolactin. He had seen his GP due to a cough, who then noted the patient had not progressed through puberty and organized further testing. On examination he had a BMI of 47. His height was 178 cm with a target of 184.5 cm (range 176-193). He had bilateral gynaecomastia with micropenis and pre-pubertal testes. He had never shaved and his voice was high-pitched. He did not report anosmia. Visual fields were normal. There was no relevant family history and his older brother had gone through puberty normally. He was otherwise healthy working as a car mechanic. Investigations showed raised Prolactin at 21,036mU/l. Gonadotrophins were suppressed with Testosterone at 1.6nmol/l. The rest of his anterior pituitary profile was normal including a normal short synachten test. Pituitary MRI showed expanded right side of the pituitary fossa with a rounded 11 x 11 x 11 mm mass. There was minimal bulging into the suprasellar system, but no contact with optic nerve or the chiasm. Bone age was calculated as 17.95 (TW2), and 16.48 (TW3). A diagnosis of macroprolactinoma was established and he was commenced initially on Cabergoline 500 mg weekly with the usual precautions for the risk of CSF leak and impulsive behavior. He was reviewed 2 months later and his Prolactin had improved to 8,885mU/l. Then at 4 month review the Cabergoline dose was increase to 500 mg twice weekly as Prolactin had plateaued. He was also started on testosterone replacement with testosterone gel to induce puberty. Current status; He is now 12 months post diagnosis. His Cabergoline dose is 1.5 mg twice weekly and latest Prolactin is 3,804mU/l. Repeat MRI showed decreased volume of the macroadenoma. His testosterone has increased to 13.5nmol/land he has developed body and facial hair. He also reports sexual drive and erections.

Discussion points:

• Strategies for puberty induction in the context of macroprolactinoma

• Further optimization of Dopamine agonist at this level of Prolactin.