Endocrine Abstracts

Background: Measurement of mean serum growth hormone (GH) during an oral glucose tolerance test (OGTT) is currently used for determination of disease activity in patients with acromegaly post-treatment. In contrast to normal subjects, GH secretion in acromegalic patients is largely non-pulsatile, even after treatment.

Aim: To determine if random serum GH correlated with mean serum GH during OGTT in patients with acromegaly post-treatment. Furthermore, we wanted to know whether random serum GH could be used as a measure of disease activity in these patients.

Methods: A retrospective analysis of 365 pairs of random and mean GH values on OGTT from 85 acromegalic patients was performed. Mean GH values on OGTT were obtained by calculating the mean of serum GH taken every 30 minutes for 2 hours following ingestion of 75 g of oral glucose. All patients had previously been treated. Forty-two patients needed medications to control disease activity at the time of the study.

Results: Random GH and mean GH on OGTT were shown to have a significantly positive linear correlation (Pearson correlation =0.965; P < 0.01). The sensitivity of random GH < 5 mIU/l in detecting patients who are in remission (mean GH ≤ 5 mIU/l) was 83.7% and the specificity was 96.8%. The sensitivity of random GH > 10 mIU/l in detecting patients with active disease (mean GH > 5 mIU/l) was 56.9% and the specificity was 99.3%.

Conclusion: There is a strong correlation between random GH and mean GH on OGTT in previously treated patients with acromegaly. Furthermore, random GH <5 or >10 mIU/l are highly specific tests of disease remission and active disease respectively. We therefore suggest that OGTT, which requires in-patient admission, need only be performed to assess disease activity in previously treated acromegalic patients if random GH is 5–10 mIU/l.