A 42-year-old woman presents to the clinic complaining of dry skin, fatigue, and weight gain over the past 3 months. She is not on any medications and there is no significant medical history.On physical examination, her blood pressure is 110/70 mm Hg, pulse 52/min, and heart and lungs are normal. Her skin feels rough and dry, but the rest of the examination is normal. Her biochemistry is normal but the thyroid-stimulating hormone (TSH) level is 39 mU/L (0.5-5 mU/L). Which of the following is the most likely cause for her elevated TSH?
High-Yield Explanation
Autoimmune hypothyroidism is the most common cause of hypothyroidism in adults. It is several times more common in women than in men and occurs most often between the ages of 40 and 60. Post ablative hypothyroidism (radiation or surgery induced) can also occur if the patient has a history of thyroid surgery or neck radiotherapy. Medications such as amiodarone or lithium can also cause hypothyroidism as a side effect of their use if there is a history of such medication use.