RATIONALE: Resistance to thyroid hormone (RTH) syndrome is an uncommon disorder of thyroid function that is frequently misdiagnosed or overlooked clinically. We identified a heterozygous mutation in the THRβ gene (c.1357C > A p.Pro453Thr) in a patient with resistance to thyroid hormone beta. This locus variation has rarely been reported domestically or internationally. PATIENT CONCERNS: The patient, a 13-year-old female presenting with goiter, was found to have persistent high free triiodothyronine and free thyroxine levels with a non-suppressed thyroid-stimulating hormone in the absence of classic hyperthyroid symptoms. DIAGNOSES: Based on the patient's history, physical examination, imaging studies, and genetic testing, the diagnosis of resistance to thyroid hormone was definitively established. INTERVENTIONS: The medication was discontinued based on the patient's clinical status. The management plan was transitioned to a strategy of watchful waiting, with scheduled follow-ups to monitor the patient's status. OUTCOMES: Following a genetic diagnosis, the patient has been followed for 24 months under an active surveillance strategy, which includes annual thyroid function tests. LESSONS: Enhanced clinical vigilance is imperative to mitigate diagnostic bias and errors associated with this condition, thereby ensuring timely and accurate diagnosis and appropriate therapeutic intervention.
Yang et al. (2026) studied this question.
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