Thyroid Disorders USMLE Step 1 Practice Question
A 6-year-old girl is brought to the clinic by her parents who report that she has not grown well since infancy despite adequate nutrition. On examination, she is at the 3rd percentile for height, has a broad, flat nasal bridge, periorbital puffiness, coarse facial features, and delayed speech development. Her skin appears dry and her hair is brittle. Serum TSH is 18.2 mIU/L, free T4 is 0.4 ng/dL (normal 0.8-1.8), and thyroid peroxidase (TPO) antibodies are negative. Newborn screening records from birth are unavailable. Which of the following is the most likely diagnosis?
Answer choices
- AAcquired autoimmune hypothyroidism (Hashimoto's thyroiditis)
- BCentral hypothyroidism secondary to pituitary hypoplasia
- CIodine deficiency hypothyroidism
- DCongenital hypothyroidism with delayed diagnosisCorrect answer
- EPrimary hypothyroidism secondary to thyroid hormone resistance
- FTransient hypothyroidism from maternal iodine exposure in utero
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.