Endocrine Abstracts (2009) 20 P587

GH response to oral glucose tolerance test: a comparison between patients with pituitary disease and healthy subjects

Elisa Verrua, Cristina Lucia Ronchi, Daniela Ilaria Ferrari, Luca Olgiati, Emanuele Ferrante, Marcello Filopanti, Andrea Gerardo Lania, Paolo Beck-Peccoz & Anna Spada

Unit of Endocrinology and Diabetology, Department of Medical Science, Fondazione IRCCS Ospedale Maggiore Policlinico, University of Milan, Mangiagalli e Regina Elena, Milan, Italy.

Background: GH response to oral glucose tolerance test (OGTT) is currently used for the definition of disease remission in acromegaly. This test has been poorly investigated in other pituitary diseases.

Aim: To evaluate the impact of a pituitary disease other than acromegaly on GH response to OGTT.

Patients and methods: Eighteen patients (13 F & 5 M, age: 50.7±13.1 years) with different pituitary diseases (i.e. non-functioning pituitary adenomas, n=14, empty sella, n=1, meningiomas: n=3) were evaluated. Eight of these patients underwent neurosurgery and 2 underwent radiotherapy. None of them had history of diabetes mellitus, GH deficiency or acromegaly, renal/liver failure or nutritional disorders and none was treated with drugs interfering with GH secretion. 45 sex-, age- and BMI-matched healthy subjects were investigated as controls. All patients and subjects were studied for IGF-I and GH levels before and during OGTT.

Results: IGF-I levels, evaluated as standard deviation score, were similar between the 2 groups (−1.00±0.58 vs −0.38±1.14, P=NS). All patients and controls had post-glucose GH nadir levels <1 ng/ml. Mean GH nadir was slightly higher in patients with pituitary disease than in controls (0.13±0.10 vs 0.08±0.09 ng/ml, P=0.08), being higher in females than in males only in the control group (0.10±0.09 vs 0.075±0.08 ng/ml, P<0.05). However, the time course of GH response was different between the two groups, GH levels being significantly higher in patients than in controls at time 90 and 120 min (P<0.01).

Conclusion: GH response to OGTT appears to be dysregulated in patients with pituitary tumors, possibly as a consequence of hypothalamic alterations.