Endocrine Abstracts

Treatment of acromegaly aims primarily to reverse the increased mortality and morbidity associated with active disease to that of the non-acromegalic population. Recent evidence indicates that the best biochemical criteria for successful treatment should be a mean GH<2micrograms per litre (approximately 4milliunits per litre). Although a 'test dose' of octreotide (OTD) is recommended prior to use of depot somatostatin analogues (SSAs), there remains no consensus regarding the criteria that predict a response to treatment. No studies have examined the value of an OTD in predicting longer term GH and IGF1 suppression with depot SSA therapy.

We retrospectively evaluated the predictive value of both the GH nadir and mean GH following an OTD in identifying acromegalic subjects who subsequently achieved disease remission with depot SSA therapy (octreotide or lanreotide). We hypothesised that either a nadir GH<2milliunits per litre or mean GH<4milliunits per litre would predict remission on long term SSAs.

41 subjects underwent an OTD where GH was measured hourly for a total of 6 hours following an injection of octreotide 50micrograms subcutaneously. 15/41(37%) achieved a nadir GH<2milliunits per litre and 7/41(17%) a mean GH<4milliunits per litre. 33 subjects were subsequently treated with depot SSAs as primary(13) or adjuvant(20) therapy. Of subjects with a nadir GH<2milliunits per litre, 85% achieved a mean GH<4milliunits per litre within 18 months of therapy. Of subjects with a nadir GH>2milliunits per litre; only 15% (chi-squared,12.9;p<0.001) had achieved a mean GH<4milliunits per litre at current follow up, median 15 months (3-66). However, of those subjects with a mean GH>4milliunits per litre after an OTD, 35% achieved a mean GH<4milliunits per litre on long term SSAs.

Our data suggest that a nadir GH<2milliunits per litre following an OTD is a good predictor of remission with depot SSA therapy used as primary or adjuvant therapy.