LAUSR

A 43-year-old woman with a 1-year history of 6-kg weight loss and weakness was diagnosed with primary hypothyroidism and started levothyroxine one week before. She presented to the emergency department with a 4-day history of abdominal pain and vomiting. Physical examination revealed BP 80/35 mm Hg, HR 110 bpm, afebrile, slim build and generalized cutaneous hyperpigmentation, especially in the knuckles, the palmar and plantar creases (Fig. 1) and involving gingival mucosa and mucosal surface of lower lip (Fig. 2). Laboratory tests showed decreased serum sodium levels (131 mmol/L) and the remainder was unremarkable. A final test was quickly performed in the emergency room. What is the diagnosis?