Endocrine Abstracts

Cabergoline is a dopamine agonist that may be used as primary or adjunctive therapy for acromegaly. Although one study suggested biochemical control may be achieved in a substantial proportion of patients (Abs et al, JCEM 1998), it is still commonly perceived to be a relatively ineffective treatment, possibly on account of inadequate dosing.

We performed a retrospective case notes review of 9 consecutive acromegalic patients to determine the effectiveness, tolerability and doses required for biochemical remission of acromegaly. The cohort consisted of 5 male, 4 female, aged 31–92 at presentation. At diagnosis, median growth hormone nadir during a standard oral glucose tolerance test was 11.2mU/l (range 6.0–45.1mU/l) with a median IGF-I, 585 ng/ml (285–739 ng/ml). All 9 patients had normal anterior pituitary function and serum prolactin. MRI scan revealed 3 adenomata, 2 partially empty sellae and 4 structurally normal pituitary glands. 3 patients had trans-sphenoidal surgery 1–3 months, and 1 patient had pituitary radiotherapy 18 years prior to commencement of cabergoline.

All had biochemical growth hormone excess when cabergoline was commenced; median serum IGF-I was 183% (range 141–369%) above the upper limit of the age-adjusted normal range. On a median weekly dose of cabergoline of 0.5 mg od (range 0.2–1 mg od) serum IGF-I fell to within the normal range in 5/9 patients and by 63 and 116% in 2 patients. Cabergoline was completely ineffective in 1 patient (serum IGF1 736 ng/ml pre- and 762 ng/ml on cabergoline). Duration of treatment was 4 to 52 months. Cabergoline was well tolerated in all 9 patients and 7 reported improvement in symptoms

Cabergoline is an effective and well tolerated primary or adjunctive therapy for acromegaly. Dose titration is necessary to achieve maximum effect and substantially larger doses are required than for the treatment of prolactinoma. All doses used were easily tolerated with no adverse effects.