A 25-year-old man presents with 3 months of polyuria and increased thirst. The patient suffered trauma to the base of the skull in a motorcycle accident 4 months ago. A 24-hoururine collection shows polyuria but no evidence of hematuria, glucosuria, or proteinuria. The pathogenesis of polyuria in this patient is most likely caused by a lesion in which of the following areas of the brain?

Central diabetes insipidus may be caused by head trauma that damages the posterior lobe of the pituitary (neurohypophysis) and interrupts the secretion of ADH. One fourth of cases of central diabetes insipidus are associated with brain tumors, particularly craniopharyngioma. The other choices do not involve areas of the brain that secrete ADH. The anterior pituitary (adenohypophysis, choice A) does not secrete ADH.Diagnosis: Diabetes insipidus