A 30-year-old female presents with 3 months of fatigue, cold intolerance, weight gain, constipation, and dry skin. Physical examination reveals delayed deep tendon reflexes and diffuse non-tender goiter. What is the most sensitive screening test?
Answer and explanation
Correct answer: C. Serum thyroid-stimulating hormone (TSH) concentration
- Step 1: The patient presents with signs and symptoms of primary hypothyroidism (most commonly Hashimoto thyroiditis).
- Step 2: Due to the sensitive logarithmic feedback relationship between pituitary and thyroid, serum TSH is the most sensitive initial screening test.
- Step 3: An elevated TSH followed by low free T4 confirms primary hypothyroidism.
Answer
Serum thyroid-stimulating hormone (TSH) concentration.
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