Seen in the ED: Generalized Weakness

Persistent generalized weakness and decreased oral intake bring a man in his early 60s with hx of thyroid cancer to the ED. Do ECG and labs suggest a diagnosis?

Patient history: A man in his early 60s with a history of thyroid cancer and a recent admission presents to the hospital for 4 days of generalized weakness and decreased oral intake. He denies any pain, palpitations, vomiting, diarrhea, focal weakness, syncope, trauma or other complaints.

Vital signs and physical examination: Vital signs are normal except for a soft blood pressure of 102/52 mm Hg and a pulse of 118 beats/min. Initial physical exam is otherwise normal except for dry mouth.

Initial diagnostic testing:

  • ECG: sinus tachycardia, no S1Q3T3
  • Labs: BUN/Cr 65/2.5, Na 126, Hb 14.6, WBC normal, UA elevated specific gravity but otherwise not impressive.
  • Imaging: chest radiograph, no abnormality detected

What is the most likely diagnosis?