A case of thyroid hormone resistance with thyroid regrowth: implications of misdiagnosis on patient care

TL;DR

A man was misdiagnosed with resistant hyperthyroidism, leading to unnecessary surgery and treatment, and later showed signs of thyroid hormone resistance.

Contribution

This case highlights the diagnostic challenges and treatment complications of thyroid hormone resistance syndromes.

Findings

The patient had persistently elevated TSH levels despite variable FT4 levels.

Thyroid regrowth occurred after total thyroidectomy, complicating the misdiagnosis.

Misdiagnosis led to inappropriate iodine-131 therapy and medical management.

Abstract

We present the case of a male patient misdiagnosed with resistant hyperthyroidism who erroneously underwent total thyroidectomy complicated by thyroid tissue regrowth. Subsequent iodine-131 (I-131) radiation therapy and medical management further confounded the misdiagnosis. Serological examination in the following years revealed persistently elevated thyroid stimulating hormone (TSH) levels ranging from 45.7 μIU/mL (SI: 45.7 mIU/L) to 134.0 μIU/mL (SI: 134.0 mIU/L) (reference range, 0.550-5.00 μIU/mL [SI: 0.55-5.00 mIU/L]) with variable free thyroxine (FT4) levels ranging from 0.80 ng/dL to 8.1 ng/dL (SI: 10.3 pmol/L to 104.3 pmol/L) (reference range, 0.90-1.70 ng/dL [SI: 11.5-21.8 pmol/L]). Thyroid hormone resistance syndromes (RTH) are characterized by thyroid hormone resistance in organ tissues. Clinical presentation varies based on the severity of thyroid hormone dysregulation and the location of hormone resistance. RTH is often misdiagnosed due to variable phenotypic and biochemical presentations, resulting in erroneous medical and surgical treatments that further complicate patient management. The purpose of this report is to highlight the complex treatment course of this patient and describe challenges faced when diagnosing and managing RTH.

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