Benserazide and nomifensine in the diagnosis of prolactin-secreting pituitary adenomas

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Abstract
Benserazide, an inhibitor of dopa-decarboxylase, stimulates prolactin (Prl) release in normal women and in puerperae; nomifensine, a dopaminergic drug able to release dopamine and to inhibit its re-uptake at the post-synaptic level, inhibits Prl release in the same subjects. Similar modifications of Prl release are evident in selected cases of non-tumoral hyperprolactinemia, while neither drug modifies Prl release in patients with a Prl-secreting pituitary adenoma. The effects of these drugs in patients with a Prl-secreting pituitary adenoma, in patients with functional hyperprolactinemia and in patients with minor abnormalities of sellar tomography were compared. Neither drug modified Prl release in patients with macro- or microadenomas; several patients in the remaining groups failed to respond to one or both tests, the concordance between the 2 tests averaging 75%. Patients responding to both tests, to one test or to neither test showed progressively higher basal Prl levels. Since benserazide and nomifensine can indicate the presence of a pituitary adenoma earlier than sellar tomography, results indicate that patients with no Prl response to one or to both tests probably harbor a pituitary adenoma which cannot yet be revealed by sellar tomography.