Evaluation of growth hormone stimulation tests in cured acromegalic patients

We have evaluated the GH peak response to insulin tolerance test (ITT) and to GHRH + arginine in 11 patients cured of acromegaly after treatment with surgery/radiotherapy and compared them to a control group matched for age and sex. GH peak response was significantly higher in the control group than in the patient group (11.21 ± 6.98 vs. 4.46 ± 6.90 ng/ml, p=0.010). Seven patients had a GH peak response of less than 3 ng/ml, compatible with the diagnosis of GH deficiency. Peak GH response after GHRH + arginine was significantly lower in the group of patients with GH peak of less than 3 ng/ml during ITT as compared to the group with GH peak of more than 3 ng/ml, and in all cases the diagnosis of GH deficiency was confirmed. Mean IGF-I level was not different between the patients and controls, as well as between patients with and without GH deficiency diagnosed by the stimulation tests. Conclusion: The incidence of GHD diagnosed by stimulation tests is high in patients cured of acromegaly.