hypertyreoidism

Hypertyreoidism, also known as hyperthyroidism, is a condition in which the thyroid gland produces excess thyroid hormones, mainly thyroxine (T4) and triiodothyronine (T3). The thyroid helps regulate the body's metabolism, heart rate, temperature control, and energy use. When hormone levels are elevated, metabolic processes accelerate.

The most common causes are Graves' disease, an autoimmune disorder, and toxic nodular disease, such as toxic multinodular goiter or a toxic thyroid nodule. Less common causes include thyroiditis, which may release stored hormones into the bloodstream, and less often pituitary or hypothalamic disorders. In Graves' disease, antibodies stimulate the TSH receptor, increasing thyroid hormone production.

Symptoms vary but often include weight loss despite normal or increased appetite, rapid or irregular heartbeat (tachycardia or atrial fibrillation), heat intolerance, sweating, tremor, anxiety, irritability, and sleep disturbances. Other signs may include increased bowel movements, muscle weakness, fatigue, menstrual changes, and a goiter. Eye changes can occur with Graves' disease, including bulging eyes, redness, and irritation, though not in all patients.

Diagnosis relies on laboratory testing and clinical assessment. A low or suppressed thyroid-stimulating hormone (TSH) level with elevated free T4 and/or free T3 supports hyperthyroidism. Tests to identify the cause may include thyroid antibodies (such as TSH receptor antibodies), radioactive iodine uptake, and thyroid ultrasound. Electrocardiography may be used to assess heart rhythm in symptomatic individuals.

Treatment options depend on the underlying cause and patient factors. Antithyroid medications (e.g., methimazole) reduce hormone synthesis, while beta-blockers help control rapid heart rate and tremor. Definitive options include radioactive iodine therapy to ablate thyroid tissue or surgical removal (thyroidectomy). After treatment, hypothyroidism may occur and require lifelong thyroid hormone replacement. With appropriate management, most individuals experience symptom relief and good long-term outcomes.