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Growth hormone (GH) is essential not only for normal growth during childhood, but also for the acquisition of bone mass and muscle strength in both sexes. This process is completed after the achievement of adult height in the phase of transition from adolescence to adulthood. Adolescents with childhood onset GH deficiency (GHD) show reduction of bone mineral density, decrease in lean body mass, increase in fat mass, and deterioration of the lipid profile. For this reason, continuation of GH replacement therapy in the transition age is recommended in all patients with a confirmed diagnosis of GHD. To confirm the diagnosis of GHD, GH treatment should be discontinued for at least 1 month after the attainment of adult height, and the patient should be re-evaluated for GH secretion. Current guidelines indicate that retesting is not required for those with a transcription factor mutation, more than 3 pituitary hormone deficits, or isolated GHD associated with an identified mutation. The key predictors of persistent GHD are its severity, the presence of additional pituitary hormone deficits, low insulin-like growth factor I (IGF-I) concentration, and the presence of structural hypothalamic-pituitary abnormalities Treatment should be initiated with a low dose (0.2-0.5 mg/day s.c.) and then adjusted according to IGF-I concentrations.

Background: In past decades, our understanding of the vasopressin-mediated renal concentration mechanism has improved considerably due to the discovery of new endocrine-related neurotransmitters and the elucidation of the roles of crucial molecular players in this process. The identification of disease-causing genes in hereditary disorders of water balance has been extremely helpful in identifying these pivotal molecules. Acquired diseases, however, are the most frequent causes of impaired water homeostasis. Diagnosis: The clinical and biochemical diagnosis of hormonal deficit is confirmed by standard laboratory tests, but recent advances in imaging techniques have shed new light on the pathophysiology of many of these diseases. Management: Magnetic resonance imaging (MRI) permits identification of the posterior pituitary in vivo and can clearly delineate the shape, size and enhancement pattern of the pituitary stalk, as well as its functional integrity. Thickening of the pituitary stalk is a common finding on MRI scans in several pituitary stalk pathologies, but it is not specific to any single pathological subtype. However, biopsy of an enlarged pituitary stalk should be reserved for selected patients with hypothalamic-pituitary mass or with progressive thickening of the pituitary stalk.

Magnetic resonance imaging (MRI) allows a detailed and precise anatomical study of the pituitary gland by differentiating between the anterior and posterior pituitary lobes. The identification of posterior pituitary hyperintensity, now considered a marker of neurohypophyseal functional integrity, has been the most striking advance for the diagnosis and understanding of anterior and posterior pituitary diseases. The advent of MRI has in fact led to a significant improvement in the understanding of the pathogenesis of disorders that affect the hypothalamo-pituitary area. Today, there is convincing evidence to support the hypothesis that marked MRI differences in pituitary morphology indicate a diverse range of disorders which affect the organogenesis and function of the anterior pituitary gland with different prognoses. Furthermore, the association of extrapituitary malformations accurately defined by MRI has supported a better definition of several conditions linked to pituitary hormone deficiencies and midline defects. MRI is a very informative procedure that should be used to support a diagnosis of hypopituitarism. It is useful in clinical management, because it helps endocrinologists determine which patients to target for further molecular studies and genetic counselling, which ones to screen for additional hormone deficits, and which ones may need growth hormone replacement into adult life.