CENTRAL DIABETES INSIPIDUS: A STEP FORWARD

Key words: Central diabetes insipidus, Posterior pituitary hyperintensity, Pituitary stalk, Anterior pituitary gland, Magnetic resonance imaging

Diabetes insipidus is a multifactorial disease caused by the lack of secretion of vasopressin, its physiologic suppression following excessive water intake, or kidney resistance to its action. The clinical and laboratory diagnosis is confirmed by standard tests, but recent advances in molecular biology and imaging techniques have shed a new light on the physiopathological aspects. Magnetic resonance imaging (MRI) allowed identification of the posterior pituitary gland in vivo and hypothalamic-pituitary abnormalities. The lack of posterior pituitary hyperintensity at MRI is the hallmark of hypothalamic-posterior pituitary disorders and may represent the early stage of occult local tumors. Evidence of posterior pituitary hyperintensity does not necessarily indicate that functional integrity of the hypothalamic- neurohypophyseal axis is preserved. Thickened pituitary stalk is a common finding of several local inflammatory and autoimmune diseases or germinoma. A progressive increase in the size of the anterior pituitary gland should alert physicians to the possibility that a germinoma is present, whereas a decrease can suggest the presence of an inflammatory or autoimmune process. Most children with acquired central diabetes insipidus have abnormal findings on MRI, which may change over time, and at least half develope anterior pituitary hormone deficiencies.