Hyponatremia is associated with which diagnosis?

Hyponatremia is associated with which diagnosis?

• A. Chronic kidney disease
• B. Hepatitis C infection
• C. Bronchogenic lung cancer
• D. Gastric ulcer

Answer: (C)

Hyponatremia in this context is most often due to SIADH, where a tumor secretes antidiuretic hormone, causing the kidneys to reabsorb water and dilute the serum sodium. Small cell (bronchogenic) lung cancer is the classic source of ectopic ADH, leading to euvolemic hyponatremia with low serum osmolality and inappropriately concentrated urine. This connection is why bronchogenic lung cancer best fits the question. Other conditions listed can cause hyponatremia through different mechanisms (kidney dysfunction, cirrhosis, etc.), but they’re not the classic tumor-related cause.

Hyponatremia in this context is most often due to SIADH, where a tumor secretes antidiuretic hormone, causing the kidneys to reabsorb water and dilute the serum sodium. Small cell (bronchogenic) lung cancer is the classic source of ectopic ADH, leading to euvolemic hyponatremia with low serum osmolality and inappropriately concentrated urine. This connection is why bronchogenic lung cancer best fits the question. Other conditions listed can cause hyponatremia through different mechanisms (kidney dysfunction, cirrhosis, etc.), but they’re not the classic tumor-related cause.