The octreotide test dose is not a reliable predictor of the subsequent response to somatostatin analogue therapy in patients with acromegaly

Abstract

In many centres, a test dose (TD) of octreotide is administered before commencing somatostatin analogue therapy (SAT), although the merits of this procedure are uncertain. We have analysed the value of the GH response to a TD in predicting the efficacy of subsequent SAT in 47 patients with acromegaly (25 male, median age 51 years, range 20-82). The primary goal of SAT was a mean GH of , 5 mU/l. Median baseline GH was 19.3 mU/l (2.2-233 mU/l) and with the TD fell by 78% (35 -98%) to a nadir of 4.2 mU/l (, 0.3-85 mU/l). Optimal predictive power was observed when GH fell to , 5 mU/l after the TD. With this criterion, the TD had a positive predictive value (PPV) of achieving the primary goal on SAT of 82% and a negative predictive value (NPV) of 50%. However, baseline GH was also highly predictive of the likelihood of successful SAT (GH , 5 mU/l). The GH response to the TD had PPV of 83% and NPV of 61% of normalising IGF-I on SAT. In summary, baseline GH and nadir after a TD are highly predictive of a good response to SAT; however, a poor response to a TD does not exclude an optimal response to SAT. Furthermore, failure to achieve biochemical control does not equate to no benefit, as biochemical improvement was seen in every patient; therefore, no patient should be deprived of octreotide therapy because of the result of a TD. In conclusion, our data indicate that the octreotide TD has no place in selecting patients for SAT.European Journal of Endocrinology 154 267-274

An audit of treatment outcome in acromegalic patients attending our center at Bergamo, Italy

“…As already reported [34][35][36][37], results of SA as primary or adjuvant treatment were not different. In contrast to what recently reported [38], but in agreement with others [39], acute octreotide administration was useless in predicting response to long-term treatment. Owing to the large prevalence of responsiveness to SA in acromegalic population and the very little difference in post-test probability as compared to pre-test one, it seems thus better to evaluate results of a short (3-6 months) treatment, that were convincingly reported to predict reliably the results of chronic treatment [34,35].…”

Dynamic tests for the diagnosis and assessment of treatment efficacy in acromegaly

“…After acute octreotide administration, GH levels fall in 50-65% of patients [54][55][56][57][58][59][60]. The criteria used to define the response to acute octreotide administration and the chronic response to somatostatin analogue therapy vary among studies.…”

Pituitary-independent effect of octreotide on IGF1 generation

“…It has been suggested that, in patients with acromegaly, octreotide treatment reduces circulating IGF1 more than anticipated from the suppression of the endogenous GH secretion, and several groups have commented on this phenomenon (10,(26)(27)(28). These findings suggest that octreotide action is not confined to the suppression of GH secretion, but that it may also have a direct effect on IGF1 generation.…”