Familial non-immune hyperthyroidism

Familial Non-Immune Hyperthyroidism (FNIH) is a rare endocrine disorder characterized by the overproduction of thyroid hormones, known as thyroxine (T4) and triiodothyronine (T3), without the presence of autoimmunity. This condition is also referred to as familial hyperthyroidism without autoimmune involvement. It is a genetic condition that affects the thyroid gland, leading to symptoms associated with hyperthyroidism.

Causes

Familial Non-Immune Hyperthyroidism is primarily caused by mutations in the TSH receptor gene. These mutations lead to an increased sensitivity and overactivity of the thyroid gland to the normal circulating levels of thyroid-stimulating hormone (TSH), resulting in excessive production of thyroid hormones. Unlike other forms of hyperthyroidism, such as Graves' disease, FNIH is not caused by an autoimmune response.

Symptoms

The symptoms of Familial Non-Immune Hyperthyroidism are similar to those of other types of hyperthyroidism and may include:

• Increased heart rate or palpitations
• Weight loss despite normal or increased appetite
• Nervousness, anxiety, or irritability
• Tremors
• Heat intolerance and increased sweating
• Changes in menstrual patterns in women
• Enlarged thyroid gland or goiter

Diagnosis

Diagnosis of Familial Non-Immune Hyperthyroidism involves a combination of clinical evaluation, laboratory testing, and genetic testing. Laboratory tests typically show elevated levels of thyroid hormones (T3 and T4) with non-suppressed or inappropriately normal TSH levels. Genetic testing can confirm the presence of mutations in the TSH receptor gene.

Treatment

The treatment of Familial Non-Immune Hyperthyroidism aims to normalize thyroid hormone levels and alleviate symptoms. Treatment options may include:

• Antithyroid medications to reduce thyroid hormone production
• Radioactive iodine therapy to destroy overactive thyroid cells
• Surgical removal of part or all of the thyroid gland in severe cases

Prognosis

With appropriate treatment, individuals with Familial Non-Immune Hyperthyroidism can manage their symptoms and maintain normal thyroid hormone levels. However, they may require lifelong monitoring and treatment adjustments.

Epidemiology

Familial Non-Immune Hyperthyroidism is a rare condition, and its exact prevalence is unknown. It can affect individuals of any age but is often diagnosed in childhood or early adulthood. The condition has an autosomal dominant pattern of inheritance, meaning a child of an affected parent has a 50% chance of inheriting the disorder.