Thyroid Hormone Resistance Syndrome in an Adolescent Girl: A Case Report

Abstract

Introduction: Resistance to Thyroid Hormones (RTH) is a rare, hereditary disease characterized by diminished sensitivity of target tissues to thyroid hormones. Most cases (~85%) are caused by mutations in the thyroid hormone receptor beta (THRβ) gene (RTHβ). The clinical spectrum of RTHβ is quite broad and highly heterogeneous, and the hallmark of the condition is a paucity of signs and symptoms of thyroid dysfunction despite elevated levels of T4 and T3, with a concomitant non-suppressed TSH. Case Report: Here, we describe a rare case of RTHβ in a female adolescent who was initially misdiagnosed and treated for Graves’ disease, but whose unusual evolution motivated her transference to a tertiary center. The patient exhibited mild manifestations, presenting with a goiter without compressive symptoms and some degree of cognitive impairment with learning disability. Misdiagnosis of RTHβ as Graves’ disease can lead to unnecessary treatments such as anti-thyroid medication, thyroidectomy or radioiodine, but treatment is generally not necessary for most patients with RTHβ. Discussion and Conclusion: Establishing the diagnosis of RTHβ can be challenging. It must be considered in patients who present with a goiter and increased thyroid hormone levels with an unsuppressed TSH, to potentially avoid an incorrect diagnosis of primary hyperthyroidism and the implementation of unnecessary and harmful treatments. Most patients with RTHβ are asymptomatic, and in children, particular attention must be paid to growth, bone maturation, and mental development.