Growth of prolactinoma despite lowering of serum prolactin by bromocriptine.

Four patients with macroprolactinomas treated with bromocriptine had tumor growth and visual loss despite marked reduction in their serum prolactin levels. Explanations for this dissociation of tumor growth and prolactin measurement might include noncompliance. Patients treated with bromocriptine require periodic examination by computed tomographic scan or magnetic resonance imaging and neuro-ophthalmological evaluation in addition to monitoring of serum prolactin.