Secretion of alpha and TSH-beta subunits in patients with acromegaly: an in vivo study

Plasma alpha and TSH-beta subunit responses to iv administration of GHRH were examined in 19 patients with active acromegaly. In 4 patients (21%), plasma alpha subunit levels were increased over 50% of basal levels after administration of GHRH, whereas plasma TSH-beta subunit levels were increased in response to GHRH in another 5 patients (26%). No patient showed simultaneous increases of alpha and beta subunits. After successful surgery, alpha and TSH-beta subunits did not respond to GHRH. These findings support the idea that some pituitary adenomas in acromegaly cosecrete GH and either alpha subunit or TSH-beta subunit.