History: A 50 year old housewife complains of progressive weight gain of 20 pounds in 1 year, fatigue, slight memory loss, slow speech, dry skin, constipation, and cold intolerance.

Physical examination: Vital signs include a temperature 96.8^oF, pulse 58/minute and regular, BP 140/100. She is moderately obese and speaks slowly and has a puffy face, with pale, cool, dry, and thick skin. The thyroid gland is slightly enlarged, firm, not nodular, mobile, and not tender. The deep tendon reflex time is delayed.

Laboratory studies: CBC and differential WBC are normal. The serum T4 concentration is 3.8 ug/dl, the serum TSH is 23.0 uU/ml, and the serum cholesterol is 255 mg/dl.

1. What is the likely diagnosis?

3. What additional aspects of the history and physical examination could provide relevant information to help in the diagnosis?

4. What additional tests would help confirm the diagnosis?

5. What are the treatment options?