In diabetes insipidus, daily urine output can reach up to approximately how many liters?

• A. 5
• B. 20
• C. 10
• D. 50

Answer: (B)

In diabetes insipidus the kidneys lose the ability to concentrate urine because antidiuretic hormone (ADH) action is deficient or renal tubules are resistant to it. That means a lot of water is excreted as dilute urine, and the body must compensate with increased water intake. Because ADH normally promotes water reabsorption in the collecting ducts, its absence or insensitivity leaves these ducts impermeable to water, resulting in large volumes of urine.

In severe cases, daily urine output can be around 20 liters, which is vastly higher than the normal 1–2 liters per day. The other options are not as representative of the typical maximum: 5 liters is possible but not the peak; 10 liters is plausible but not the best depiction of the extreme; 50 liters would be unusually high in most patients. Therefore, about 20 liters per day is the best answer.