A 37-year-old woman suffers a severe head injury in a skiing accident. Shortly thereafter, she becomes polydipsic and polyuric. Her urine osmolarity is $75 \mathrm{mOsm} / \mathrm{L}$, and her serum osmolarity is $305 \mathrm{mOsm} / \mathrm{L}$. Treatment with 1-deamino-8-D-arginine vasopressin (dDAVP) causes an increase in her urine osmolarity to $450 \mathrm{mOsm} / \mathrm{L}$. Which diagnosis is correct?

Question

Quizplus · Accepted Answer

[Chapter 5, VII C; Table 5.6]. A history of head injury with production of dilute urine accompanied by elevated serum osmolarity suggests central diabetes insipidus. The response of the kidney to exogenous antidiuretic hormone (ADH) (1-deamino-8-D-arginine vasopressin [dDAVP]) eliminates nephrogenic diabetes insipidus as the cause of the concentrating defect.

A 37-Year-Old Woman Suffers a Severe Head Injury in a Skiing