Endocrine Abstracts

We present a case of a 48 year old male who presented originally with a 8mm prolactinoma. He presented with a reduced libido for 6 months, and lethargy and retro-orbital headaches for the previous 18–24 months. He had no visual disturbance. Initial investigations revealed hyperprolactinaemia with a level of over 4000 iu/L and a normal IGF1 of 184 iu/L in the presence of a pituitary macroadenoma (8 x 11mm). He responded well to Cabergoline with a noticeable improvement in all his symptoms in conjunction with fall in the prolactin levels to the reference range and reduction in size of macroadenoma. After 3 years (2009), he started describing increasing tiredness, which was associated with an increase in his IGF1 from normal to 2-3x upper reference range On direct questioning he admitted to have difficulty in getting his rings on and skin thickening. Prolonged growth hormone-oral glucose tolerance testing showed non-suppression of his growth hormone consistent with Acromegaly. He was initially mamanged conservatively, but due to persisting symptoms and a consistently raised IGF1, he was treated with pituitary surgery. Post-surgery was associated with a normalisation in Prolactn and IGF1. Histology confirmed co-secretion of Prolactin and GH. Whilst it is well recognised that co-secretion of prolactin and growth hormone can occur in significant number of patients with macroadenomas, it is usually synchronous. Asynchronous secretion is less common (<2%) and should be monitored and considered with any symptom changes and/ or with an annual assessment of IGF1/ Prolactin. It is also more unusual to see growth hormone secretion whilst on treatment with dopamine agonist medications due to the frequently found sensitivity of GH in co-secreting prolactinomas.