79歳男性、低Na血症、手や顔の不随意運動を主訴に来院。 A 79-Year-Old Man with Hyponatremia and Involuntary Movements of the Arm and Face. N Engl J Med. 2020 May 14;382(20):1943-1950. https://www.nejm.org/doi/full/10.1056/NEJMcpc1913477 病歴…