Hyperthyroidism is more common in women, people with other thyroid problems and people over 60 years old. Grave's disease, an autoimmune disorder, is the most common cause. Other causes include thyroid nodules, thyroiditis, excessive iodine intake and taking too much synthetic thyroid hormone.

Symptoms vary from person to person. These may include:

Being nervous or irritable

Mood swings

Fatigue or weakness

Heat intolerance

Trouble sleeping

Tremor

Fast or irregular heartbeat

Frequent bowel movements or diarrhea

Weight loss

Goiter, which is an enlarged thyroid that may cause the neck appear swollen

To diagnose hyperthyroidism, your doctor will review your symptoms, do a blood test and sometimes a gammafría thyroid. Treatment involves medications, radioactive iodine therapy or thyroid surgery. These treatments work differently for each person.