Hyperthyroidism
Hyperthyroidism is an overactive thyroid gland, evaluated and treated per the 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism, still the ATA's current full guideline.
Symptoms
Weight loss despite normal or increased appetite, rapid heartbeat or palpitations, heat intolerance, tremor, anxiety, and sometimes eye changes (bulging, irritation) specific to Graves' disease.
Causes and risk
Graves' disease (autoimmune) is the most common cause; toxic nodules and thyroiditis (an inflammatory, often temporary release of stored hormone) are next.
How it is evaluated
TSH, free T4, and free T3 confirm the diagnosis; thyroid antibodies and, when the cause isn't clear, a radioactive iodine uptake scan distinguish Graves' from nodules from thyroiditis, since treatment differs by cause.
Treatment
Antithyroid drugs (methimazole first-line, with a small agranulocytosis and hepatotoxicity risk to monitor for), radioactive iodine, and surgery are all guideline-supported options, chosen based on cause, goiter size, eye involvement, and patient preference. Never stop antithyroid drugs abruptly without guidance -- it's a recognized trigger for thyroid storm.
When to seek care
Thyroid storm -- high fever, racing heart, confusion, and severe agitation -- is a life-threatening emergency requiring immediate hospitalization.