A case of resistance to thyroid hormone beta and literature review: Case report.

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.