Thyroid hormone resistance

Overview

Diagram of the thyroid system

Thyroid hormone resistance is a rare condition characterized by a reduced responsiveness of the body's tissues to thyroid hormones. This condition can lead to a variety of clinical manifestations, depending on the degree of resistance and the tissues affected. It is often inherited in an autosomal dominant pattern.

Pathophysiology

Thyroid hormone resistance is primarily caused by mutations in the thyroid hormone receptor beta (THRB) gene. These mutations impair the receptor's ability to bind to thyroid hormones, such as triiodothyronine (T3) and thyroxine (T4), leading to altered feedback mechanisms and variable tissue responses.

Clinical Features

Patients with thyroid hormone resistance may present with a wide range of symptoms. Common features include elevated levels of circulating thyroid hormones with normal or slightly elevated thyroid-stimulating hormone (TSH) levels. Symptoms can vary from hyperthyroidism to hypothyroidism, depending on the tissue-specific expression of the receptor.

Diagnosis

The diagnosis of thyroid hormone resistance is based on clinical evaluation, laboratory tests showing elevated T3 and T4 with non-suppressed TSH, and genetic testing to identify mutations in the THRB gene. Differential diagnosis includes pituitary resistance to thyroid hormone and other causes of altered thyroid function tests.

Management

Management of thyroid hormone resistance is challenging and often requires a multidisciplinary approach. Treatment is usually symptomatic and may involve the use of beta-blockers to manage symptoms of hyperthyroidism. In some cases, high doses of thyroid hormone may be used to overcome the resistance.

Prognosis

The prognosis for individuals with thyroid hormone resistance varies. Many patients lead normal lives with appropriate management, although some may experience complications related to altered metabolic states.

Related Pages

• Thyroid hormone
• Thyroid gland
• Endocrinology
• Genetic disorders