Stimulation Test With Intranasal Glucagon for Corticotroph, Somatotroph and Antidiuretic Axes

Detailed Summary

The diagnosis of secondary hypoadrenalism and GH deficiency (GHD) often requires the performance of a dynamic test. The glucagon stimulation test (GST) is one of the options for evaluating hypothalamic-pituitary function, representing a stimulus for both the corticotropic and somatotropic axis, substantially safe and easily available. The standard procedure involves the intramuscular injection of 1-1.5 mg of glucagon based on the patient's weight. In addition to its antero-pituitary function, glucagon has also shown its ability to stimulate neurohypophyseal secretion. Using the copeptin dosage, it has been shown that after the administration of glucagon in healthy subjects there is a significant release of ADH. However, the available data are scarse and there is no standardized protocol for the use of the glucagon test in diabetes insipidus. At the moment, GST is not the most frequently chosen diagnostic option. In fact, despite having the advantage of being able to investigate different areas of anterohypophyseal and probably posterohypophyseal function at the same time, the test has some disadvantages: the prolonged duration makes the procedure challenging, the intramuscular injection can be unwelcome, and many variables can come into play in the definition of a normal response (age, BMI, glycemic status). The recent introduction of a single-dose nasal powder formulation (Baqsimi®) could overcome some of the limitations of classic GST and make the procedure less demanding. To date, no assessments are yet available regarding a purely diagnostic role in the context of hypopituitarism of this new formulation. Through the knowledge of the physiological response of the adrenocortical, somatotropic and ADH axis to the administration of intranasal glucagon in healthy subjects, it will be possible to evaluate its possible application in the diagnosis of GH deficiency, central adrenal insufficiency and possibly diabetes insipidus.

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