Failure to confirm a growth hormone-releasing activity of corticotropin-releasing hormone in acromegaly: comparison with the effects of other hypothalamic hormones.

We re-examined whether CRH stimulates GH secretion in acromegaly. Human CRH (100 micrograms) was given as an iv bolus to 15 patients with active acromegaly, and plasma GH levels were measured before and at intervals up to 120 min after the injection. For comparison, we assessed in all the patients the effects of TRH (500 micrograms), GnRH (100 micrograms), vasoactive intestinal peptide (100 micrograms) and peptide histidine methionine (100 micrograms), which are known paradoxically to stimulate GH secretion in acromegaly. A paradoxical GH response (greater than 50% above the basal) to TRH, GnRH, vasoactive intestinal peptide and peptide histidine methionine was observed in 12 (80%), 4 (27%), 5 (33%) and 2 (13%) patients, respectively. All the patients were responsive to at least one of these 4 peptides. However, none of the patients showed a positive GH response to hCRH. These results do not support a GH-releasing activity of CRH in acromegaly. Even if CRH has such an effect, it does not appear as potent as TRH, GnRH, vasoactive intestinal peptide and peptide histidine methionine. However, the possibility cannot be excluded that our negative data might have been due to the use of hCRH vs ovine CRH in earlier studies.