The interaction of GHRH with TRH in acromegaly: a controlled study.

In a single-blind placebo-controlled study, the effect of an iv bolus injection of 100 micrograms GHRH(1-29)NH2 on the response to 200 micrograms TRH was assessed in 10 untreated patients with acromegaly to determine whether GHRH interacts with TRH in acromegaly, as previously described in healthy subjects. The combination of GHRH(1-29)NH2 with TRH resulted in a larger increment of peak and of integrated plasma TSH and PRL levels than after TRH alone. GHRH alone had no effect on TSH secretion and only a modest effect on PRL secretion. These findings suggest that in acromegaly, like in healthy individuals, GHRH potentiates the TSH response to TRH and that the effects of GHRH and TRH on PRL secretion are additive.