Endocrine Abstracts

The patients following craniospinal irradiation (CSI) in young ages due to posterior fossa tumors had high risk of hypopituitarism. The glucagon stimulation test (GST) may be used as alternative the insulin tolerance test (ITT) in the diagnosis of GH deficiency (GHD) and central adrenal insufficiency (CAI) when insulin-induced hypoglycaemia is contraindicated e.g. history of convulsions, coronary heart disease, also it can be carry out as an outpatient. The aim of this study was to compare the GST and ITT for diagnostic GDH and CAI in patients following craniospinal irradiation (CSI) in young ages.

Methods: Thirteen patients were examined (five girls, eight boys, median age, 19 years (17; 22)). All had posterior fossa tumors in history. Median age at the time of treatment was 13 years (8; 14), Median follow-up was 5 years (3; 6). All patients received resection of the tumor, chemotherapy and CSI (35 Gy for whole brain, 55 Gy for tumor area and 32 Gy for spine). All of them performed ITT and GST. Severe GHD was diagnosed when GH was <3 ng/ml, cortisol cut-off for normal response was level 550 nmol/l.

Results: 9/13 patients diagnosed severe GHD (median GH, 0.89 ng/ml (0.6–1.4)) in GST and 12/13 patients revealed GHD (median GH, 0.85 ng/ml (0.37–1.65)) in the ITT. 9/13 patients had CAI in GST (median peak plasma cortisol, 385 nmol/l (335; 476)). But the diagnosis was refuted in 4/9 patients in ITT, peak plasma cortisol in this was >550 nmol/ml (Me 645 nmol/l (624–676)).

Conclusions: The obtained results allow us to recommend GST as initial outpatient test. If patient have peak GH <3 ng/ml and peak cortisol <550 nmol/ml in GST, ITT is required. Because the sample is small GST can’t substitute ITT now. The study continues.