History
In most situations, patients with adipsia present with obtundation caused by hypernatremic dehydration.
Information regarding the quantity and type of fluid intake may reveal the lack of thirst, pointing to the diagnosis. The presence of an inappropriately high urinary output is highly suggestive of concomitant central diabetes insipidus.
A history of brain tumors or congenital malformations suggests the possibility of a hypothalamic lesion.
Physical Examination
No physical signs are specific for adipsia. The most prominent physical signs are referable to alterations in brain water content due to hypernatremia. These alterations include the following:
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Hyperpnea
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Muscle weakness
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Restlessness
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High-pitched cry
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Insomnia
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Lethargy
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Coma
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Convulsions (uncommon, except in cases of overly rapid rehydration)
Loss of skin turgor and dry mucous membranes are evident but may not be commensurate with the grade of dehydration.
Physical signs indicative of an underlying abnormality are often evident. Examples of such physical signs include the following:
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Other midline facial defects
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Hydrocephalus
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A scar from a previous tumor surgery
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Anatomic relationships between pituitary and hypothalamic areas of interest with respect to regulation of antidiuretic hormone (ADH) secretion and thirst sensation. AN = Anterior (hypothalamic) nucleus; AP = Anterior pituitary; OC = optic chiasm; OVLT = Organum vasculosum of lamina terminalis; PA = Preoptic (hypothalamic) area; PP = Posterior pituitary; PVN = Paraventricular (hypothalamic) nucleus; SON = Supraoptic (hypothalamic) nucleus.
