• Heart complications include abnormal heart rhythm (as in atrial fibrillation, premature ventricular contractions) which may result in heart failure.
  • Hypokalemic (an abnormally low concentration of potassium ions in blood) periodic paralysis occurs in about 15% of Asian or Native American men. The condition presents with sudden paralysis and a few hyperthyroidism symptoms. It is usually precipitated by intravenous dextrose, oral carbohydrate or vigorous exercise. Attack usually lasts for 7-72 hours.
  • Decreased sexual desire, low sperm count, impotency or gynecomastia (abnormal enlargement of breasts in males) in males.
  • Thyroid storm – It is a sudden, extreme over activity of the thyroid gland. It is a life threatening emergency necessitating prompt treatment. It may be precipitated by infection, injury, surgery, poorly controlled diabetes, fear, pregnancy/labor, discontinuance of thyroid medication, or other stresses. Mortality (death) rate is 50-75%. Notable features include:
    • high fever
    • tachycardia (rapid heart rate)
    • mood swings
    • altered consciousness (even coma)
    • other symptoms may include vomiting, diarrhea, enlarged liver with mild jaundice

In old people symptoms may not be so marked (masked or apathetic hyperthyroidism). They may simply complain of weakness and sleepiness. They appear to be confused and depressed. However heart problems like abnormal heart rhythm are common in older people and they may suffer from heart failure or angina (pain in the chest).