Electrolyte Disorders USMLE Step 1 Practice Question
A 72-year-old man with SIADH secondary to small cell lung cancer presents with acute confusion and generalized seizures. Vital signs: BP 128/76 mmHg, HR 92 bpm, RR 18/min, Temp 37.2°C. Serum sodium is 118 mEq/L (osmolality 238 mOsm/kg), urine osmolality 580 mOsm/kg. He has been on fluid restriction for 2 weeks without symptom improvement. Neuroimaging shows no acute intracranial pathology. Which of the following is the most appropriate initial management?
Answer choices
- AHypertonic (3%) saline with furosemideCorrect answer
- BNormal saline infusion alone
- CFree water loading to promote diuresis
- DDesmopressin to increase ADH levels
- EHypertonic saline at rapid infusion rate to correct sodium by 20 mEq/L
- FFluid restriction with gradual sodium correction over 48 hours
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