A 47-year-old comes to the physician because of 1 month history of increased urination. She has also had dry mouth and excessive thirst. The patient has no prior medical problems and takes no medications. Her temperature is 36.9, blood pressure is 118/78 mm Hg, and pulse is 86/min. The remainder of her physical examination is normal. Her urine output and osmolality remain unchanged with water deprivation for several hours, but after administration of desmopressin, urine output decreases and urine osmolality increases. Renal clearance of which of the following substances would decrease the most after this patient's injection?

Question

Quizplus · Accepted Answer

Eductional Objective: Vasopressin and desmopressin work at the inner medullary collecting duct on V2 receptors. They induce permeability of the water and urea through the duct. The resulting rise in urea reabsorption (decreased urea clearance) enhances the medullary osmotic gradient, allowing the production of maximally concentrated urine.

A 47-Year-Old Comes to the Physician Because of 1 Month