Endocrine Abstracts

Introduction: The role of glucocorticoids in the regulation of GH secretion is not well defined. Hypercortisolism inhibits GH secretion, but also hypocortisolism is correlated with impaired GH response to dynamic tests. This study was aimed to evaluate the GH reserve after GHRH+arginine test in patients with Addison’s disease (AD) and in operated patients with Cushing’s disease (CD).

Design: Twelve AD patients (6M, 6F, aged 52±3.4 years, BMI 24.8±0.9 kg/m², mean±S.E.M.) were studied. Ten out of 18 CD patients (14F, 4M; 45±1.7 years, BMI 29.2±1.7; all underwent pituitary adenomectomy 2-18 years before) had central hypoadrenalism (group a) and 8 had normal cortisol (group b). Patients were investigated 18 h after steroid withdrawal.

Serum GH peak responses to GHRH+arginine <16.5 and <9 ng/ml were considered as partial (p-GHD) and severe (s-GHD) GH deficiency, respectively. IGF1 levels were evaluated as SDS.

Results: Four of 12 AD patients had s-GHD (peak 4.2±1.1 ng/ml) and 3 had p-GHD (peak 10.7±0.3 ng/ml); IGF1 SDS was <−2 in 7 patients. In CD group a, impaired responses to GHRH+arginine were found in 9 cases (8 had s-GHD, peak 4.7±1.2 ng/ml and 1 had p-GHD); IGF1 SDS was <−2 in 7 patients. In CD group b, three patients showed a s-GHD (peak 2.7±1.1 ng/ml) and one patient a partial deficiency; IGF1 score was <−2 in all patients with s-GHD.

In AD patients, BMI was negatively correlated with GH peak (P=0.01), and a positive correlation between cortisol and GH peak (P=0.01) was observed in males. No correlation was found between ACTH, cortisol and GH responses in groups a and b.

Conclusions: This study demonstrates a higher prevalence of GHD in hypoadrenalism than in CD patients with normalized cortisol levels and suggests the need of careful assessment of GH secretion in cured CD.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.