A 59-year-old man comes to the physician for a 1-month history of darkening of his urine and worsening fatigue. He has smoked 1 pack of cigarettes daily for 40 years. Which of the following is most likely to be seen in this patient?
Decreased serum parathyroid hormone
Decreased serum potassium
Increased serum anti-diuretic hormone
Post-synaptic nicotinic acetylcholine receptor antibodies
Pre-synaptic voltage-gated calcium channel antibodies
