A 12-year-old girl with type 1 diabetes, well-controlled on insulin, develops diffuse thyroid enlargement. TSH is elevated at 18 mIU/L, free T4 is low-normal, and thyroid peroxidase antibodies are strongly positive. The diagnosis and management is:
- A Graves disease — start methimazole
- B Simple goiter — observe without treatment
- C Hashimoto's thyroiditis — start levothyroxine since TSH is elevated with positive antibodies ✓
- D Subacute thyroiditis — give aspirin
Explanation
Hashimoto's thyroiditis (autoimmune thyroiditis) is the most common autoimmune disease of childhood, frequently co-occurring with type 1 diabetes as part of autoimmune polyglandular syndrome type 3B. The hallmarks are positive anti-TPO antibodies (>95% sensitivity), lymphocytic infiltration and goiter. Elevated TSH (even with normal or low-normal free T4) represents compensated hypothyroidism and is an indication for levothyroxine replacement to normalize TSH and prevent goiter enlargement. Graves disease presents with suppressed TSH and hyperthyroid features. Subacute thyroiditis is painful and post-viral.
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.