Prolactin response to perphenazine. A sensitive and specific test for pituitary tumor in hyperprolactinemic women

A simple biochemical screening test for prolactin-secreting pituitary tumors is needed because computed tomography is expensive and may be insensitive in the detection of microadenomas. We compared serial prolactin levels following perphenazine stimulation in 20 women with histologically documented tumors to those in 22 normal controls. In addition, seven women who were diagnosed as having functional (nontumor) hyperprolactinemia were tested. All subjects were given perphenazine, 8 mg orally. Baseline and hourly serum prolactins for six hours were compared. A 200% or greater response occurred in all control patients and functional hyperprolactinemic subjects within six hours following medication. Without exception, tumor patients exhibited a markedly blunted or absent response. This markedly diminished response pattern was compatible with the presence of a pituitary adenoma and suggests that the presence of a tumor interferes with normal pituitary secretory responsiveness.