Prolactin secretion in the empty sella syndrome, in prolactinomas and in acromegaly

Prolactin (PRL) secretion was studied in 47 patients with empty sella syndrome. Hyperprolactinemia (39-123 micrograms/l) was found in six of them. Intermittent increases in PRL were noted in another seven patients. In most subjects with empty sella syndrome and hyperprolactinemia, diurnal PRL variation was altered or impaired whereas the PRL response to TRH and L-dopa was normal. Low doses of bromocriptine (3.75-5 mg/day) normalized PRL. In patients with prolactinoma and acromegaly who had prolactin levels of 30-165 micrograms/l the diurnal PRL variation and PRL response to TRH were impaired. Patients with prolactinoma failed to suppress PRL during L-dopa test. The dose of bromocriptine required to normalize PRL ranged between 7.5 and 15 mg/day. It is concluded that in subjects with sellar changes and intrasellar cisternal herniation ("empty sella"), and with moderate increases in PRL, the responses to TRH and L-dopa and to bromocriptine may help to differentiate between the empty sella syndrome and a coexisting pituitary tumour.