Endocrine Abstracts

Background: Patients with macroprolactinoma often present with pituitary hormone deficits associated with hyperprolactinaemia or mass effect. Restoration of normoprolactinaemia and tumour shrinkage by dopamine agonist is expected to reverse, at least partially, the pituitary dysfunction. Studies assessing prospectively the pituitary function in subjects with macroprolactinoma treated with cabergoline are lacking.

Aim: To check the time course of recovery of the anterior pituitary reserve in patients with macroprolactinoma responding to cabergoline.

Patients/Methods: All patients presenting to our Department with macroprolactinoma between 10/2005-10/2007 were studied prospectively. The subjects underwent assessment of their pituitary function at diagnosis and, if deficient, at yearly intervals. Serum prolactin was checked at regular intervals during the titration of the dose of cabergoline and 6 monthly after the achievement of normoprolactinaemia. Pituitary imaging was performed 3 months after starting treatment and at yearly intervals thereafter.

Results: Thirteen patients were identified, one of which was lost to follow-up (final group 11 males and 1 female, median age at diagnosis 40.5 years (range 17–81), mean serum prolactin at diagnosis 27.247 mU/l (range 17.168–305.847)). Amongst those with pituitary hormone deficits, mean follow-up was 2.9 yrs (range 2–3). Normal prolactin was achieved in 11 and tumour shrinkage in 11 subjects. Hormone deficits at diagnosis and at last evaluation were GH (severe): 10/12 (83%) and 10/12 (83%), FSH/LH: 10/10 (100%) and 6/10 (60%) (female on oral contraceptive pill and male on Leuprolelin Acetate excluded), ACTH: 2/12 (17%) and 2/12 (17%), TSH: 4/11 (36%) (patient with primary hypothyroidism excluded) and 4/11 (36%).

Conclusions: In this first prospective study of pituitary function in treated macroprolactinoma subjects, apart from gonadotroph axis recovery (probably related to the treatment of hyperprolactinaemia), we found no improvement of pituitary hormone deficits, even after tumour shrinkage. Therefore, relevant replacement therapy should be commenced at the outset of dopamine agonist treatment.