From a group of 41 patients with acromegaly, the majority of whom had pituitary surgery as primary therapy, we have compared growth hormone responses to a test dose of octreotide across 8 hours with a 3 year random growth hormone in 22 patients who at the 3 year assessment were receiving at least 600mcg octreotide daily subcutaneously or 20mg LAR monthly intramuscularly and in 2 other patients who had achieved 3 year GH of <5 mU/l on smaller doses. Seven patients had a basal nadir of 5 mU/l or less after the test dose and 4 of them achieved GH <5 mU/l at 3 years. Seventeen had a basal nadir of 10 mU/l or less and of these 8/17 achieved GH <5 mU/l. Seven of the 24 had a nadir >10 mU/l and of these 3 had GH at 3 years of <5 mU/l. However all 3 had received external pituitary irradiation within 4 years of the 3 year assessment as compared with 2 of the <5 mU/l nadir group and 4 of the <10 mU/l group.
Our results are disappointing in predicting long-term response except that they demonstrate that the absence of a nadir GH less than 10 mU/l in the 8 hours across a test dose of 50 mcg octreotide subcutaneously was associated with failure to achieve the levels of random GH (5mU/l) associated with a normal life expectancy unless adjunctive therapy with external pituitary irradiation was given in addition to the octreotide.