A 70-year-old man presents with severe fatigue, decreased appetite, and weight gain. He also complains of constipation and dry skin. On examination, he has a slow heart rate and decreased reflexes. What are the potential causes, and what are the next steps?
The symptoms of severe fatigue, decreased appetite, weight gain, constipation, bradycardia, and delayed reflexes could suggest hypothyroidism. Other potential causes include heart disease, depression, or a neurological condition. To investigate further, the next step would be to order thyroid function tests, including serum TSH and free T4 levels.