A 39-year-old man with no past medical history developed lower-extremity edema. His primary care physician initiated treatment with furosemide and spironolactone, but there was no improvement in the patient’s edema. Laboratory testing showed the following values: sodium, 137 mEq/L; potassium, 6.22 mEq/L; glucose, 109mg/dL; serum urea nitrogen, 45mg/dL; and serum creatinine, 1.7mg/dL. In the following weeks, the patient developed paresthesias and progressive weakness in the upper and lower extremities, preventing ambulation.