An older adult with a history of small cell lung carcinoma reports muscle cramping, thirst, and fatigue. The primary healthcare provider diagnoses the client with a pituitary disorder and is treating the client accordingly. Which is an effective outcome of the treatment?

• A. Urine output of 10 L/day
• B. Urine specific gravity less than 1.025
• C. Urine osmolarity of 80 mOsm/kg
• D. Serum osmolarity of 600 mOsm/kg

Answer: (B)

When small cell lung cancer secretes ADH inappropriately, it causes the body to retain water, leading to hyponatremia. Treating this pituitary-related problem aims to reduce that excess water retention. An effective result is a decrease in the kidneys’ water reabsorption, so urine becomes less concentrated. A urine specific gravity below 1.025 indicates more dilute urine, which signals that ADH effect is decreasing and the body is excreting more free water toward a normal balance.

The other options don’t reflect the expected supportive changes after treatment: very high urine output would suggest ongoing DI or overcorrection issues; extremely dilute urine (very low osmolarity) or a very high serum osmolarity would indicate mismatched or ineffective correction of the hyponatremia and fluid status.