A 67 year old man with a 50 pack year smoking history is brought for confusion. He has no edema. Serum sodium is 118 mEq/L, serum osmolality is low, and urine osmolality is inappropriately high. Chest imaging shows a central lung mass. Which of the following is the most likely cause of his electrolyte abnormality?
- A)Ectopic ADH production by small cell carcinomaGABARITO
- B)Renal resistance to ADH from lithium use
- C)Loss of aldosterone synthesis due to adrenal destruction
- D)Osmotic diuresis from uncontrolled diabetes mellitus
- E)Primary polydipsia with suppressed ADH
Explicação
This patient has euvolemic hyponatremia with concentrated urine due to SIADH. Small cell carcinoma of the lung commonly produces ectopic ADH, causing free water retention and dilutional hyponatremia. The absence of edema helps distinguish SIADH from hypervolem... Ver explicação completa e trilha adaptativa →