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Key Features

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  • Central DI is an inability to synthesize and release vasopressin

  • Without vasopressin, the kidneys cannot concentrate urine, causing excessive urinary water loss

  • Most common causes

    • Midline defects (septo-optic dysplasia, holoprosencephaly)

    • Trauma (surgery, injury)

    • Infiltrative/neoplastic disease (tumors such as craniopharyngioma, germinoma, Langerhans cell histiocytosis, sarcoidosis)

    • Infectious (meningitis)

    • Idiopathic

  • Traumatic DI often has three phases

    • Initially caused by edema in the hypothalamus or pituitary area

    • In 2–5 days, unregulated release of vasopressin from dying neurons causes the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)

    • Finally, permanent DI occurs if a sufficient number of vasopressin neurons are destroyed

  • Of note, germinomas often present with DI, whereas DI in craniopharyngioma is more often the result of neurosurgical intervention

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Clinical Findings

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  • Onset is characterized by polyuria, nocturia, enuresis, and intense thirst, usually with a preference for cold water

  • Hypernatremia, hyperosmolality, and dehydration occur if insufficient fluid intake does not keep up with urinary losses

  • In infants, symptoms may also include failure to thrive, vomiting, constipation, and unexplained fevers

  • Severe dehydration, circulatory collapse, and seizures may be presenting symptoms in some infants

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Diagnosis

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  • Polydipsia, polyuria (> 2 L/m2/d), nocturia, dehydration, and hypernatremia

  • Inability to concentrate urine after fluid restriction (urine specific gravity < 1.010; urine osmolality < 300 mOsm/kg)

  • Plasma osmolality > 300 mOsm/kg with urine osmolality < 600 mOsm/kg

  • Low plasma vasopressin with antidiuretic response to exogenous vasopressin

  • DI is confirmed when serum hyperosmolality is associated with urine hypo-osmolarity

  • Germinomas and other infiltrative diseases are often associated with pituitary stalk thickening on MRI

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Treatment

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  • Central DI is treated with oral or intranasal desmopressin acetate (DDAVP)

  • Children hospitalized with acute-onset DI can be managed with intravenous or subcutaneous vasopressin

  • Due to the amount of antidiuresis, electrolytes should be closely monitored to avoid water intoxication

  • Infants should not be treated with DDAVP, since their primary source of nutrition is through liquid calories and this combination can result in water intoxication

  • For this reason, infants are treated with extra free water to maintain normal hydration

  • A formula with a low renal solute load and chlorothiazides may be helpful in infants with central DI

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