Hyperthyroidism
Hyperthyroidism is a state of excess thyroid hormone that accelerates metabolism, strains the heart, and affects mood and bone density over time. Graves' disease (an autoimmune condition) is the most common cause in younger adults. Early recognition and treatment prevent complications including cardiac arrhythmia and bone loss.
Symptoms
Palpitations or rapid heart rate, unexplained weight loss despite normal or increased appetite, heat intolerance, excessive sweating, tremor, anxiety, irritability, difficulty sleeping, frequent bowel movements, fatigue, muscle weakness, and -- in Graves' disease -- eye protrusion (proptosis).
Causes and risk
Graves' disease accounts for 70 -- 80% of cases and involves antibodies stimulating the TSH receptor. Toxic multinodular goiter and a single autonomously functioning nodule are other common causes. Less frequently, thyroiditis, iodine excess (from contrast dye or amiodarone), or TSH-secreting pituitary adenoma is responsible.
How it is evaluated
Low TSH with elevated free T4 and/or free T3 confirms hyperthyroidism. TSH receptor antibodies (TRAb or TSI) distinguish Graves' disease. Thyroid ultrasound and, when needed, radioactive iodine uptake scan determine the cause and guide treatment choice.
Treatment
Antithyroid medications (methimazole, propylthiouracil) reduce hormone synthesis. Beta-blockers control symptoms quickly while awaiting hormone normalization. Definitive options -- radioactive iodine ablation or thyroidectomy -- are considered for Graves' disease that does not remit after 18 -- 24 months or for toxic nodular disease.