Bromocriptine treatment of pituitary adenomas. Evaluation of withdrawal effect.

Forty patients wtih pituitary adenomas, i.e. 22 prolactinomas, 13 acromegalies, 5 non-secreting adenomas, were submitted to bromocriptine therapy 19.3 +/- 1.7 mg/day (mean +/- SEM) (range 7.5-40.0 mg/day) for 5 to 41 months (10.1 +/- 1.31). Remission of the tumoral mass was documented by air tomograms (PETG) or computerized tomograms (CT) in all but one prolactinomas and in 2 mixed HGH and PRL-secreting adenomas. Six empty sella syndromes (ESS) were produced, 4 of them during primary chemotherapy. Serum PRL decreased to normal in all but 3 prolactinomas, and serum HGH levels in 5 out of 13 acromegalies. Bromocriptine withdrawal was followed by a rapid increase of serum PRL into the pathological range, without a rapid reexpansion of the tumoral remnants: GT or surgical exploration of 4 cases, remitted until ESS showed a minimal evolution along 8 months after bromocriptine withdrawal. It is suggested that the antitumoral effect of bromocriptine is specific to lactotrophic cells and at least partially irreversible.