Which signs/symptoms are indicative of diabetes insipidus?

• A. Blurred vision and hot, dry skin
• B. Excessive thirst and urine output
• C. Diarrhea and decreased urine output
• D. Weight gain and increased urine specific gravity

Answer: (B)

Diabetes insipidus presents with polyuria and polydipsia because there isn’t enough antidiuretic hormone effect to concentrate urine. When the kidneys can’t reclaim water, they excrete large volumes of dilute urine, which triggers increased thirst to replace the water loss. That combination—excessive thirst and large urine output—is the hallmark.

Think of it this way: the defining feature is producing a lot of dilute urine, which drives thirst. The urine in DI is dilute (low specific gravity and low osmolality), and dehydration can ensue if water intake doesn’t keep up.

The other options don’t fit DI as the main picture. Blurred vision and hot, dry skin can occur with dehydration in general or with other conditions like hyperglycemia, but they’re not the characteristic signs of DI. Diarrhea with decreased urine output doesn’t align with the high-volume urine loss seen in DI. Weight gain with increased urine specific gravity would suggest water retention and concentrated urine, opposite of DI’s dilute urine and fluid loss.