Prolactin bioassay and hyperprolactinemia.

The Nb2 rat lymphoma bioassay (BA) for prolactin (PRL) was performed in 26 subjects with hyperprolactinemia, 17 of whom had radiologic evidence of a pituitary adenoma. All subjects were treated with the long acting dopamine agonist CV 205-502. The radioimmunoassay (RIA) PRL significantly decreased with treatment but the BA/RIA PRL remained essentially the same, indicating that the relative bioactivity was unaffected.