Hyperthyroidism Overview Quiz

Hyperthyroidism

• Hyperthyroidism is a condition of too much circulating thyroid hormone in the body
• Thyrotoxicosis refers to high circulating thyroid hormone regardless of its source
• Common symptoms include weight loss despite increased appetite, hand tremors, palpitations, heat intolerance, anxiety, frequent bowel movements, fine hair, increased thirst and urination, light and infrequent menstrual periods, difficulty sleeping, weakness in upper arms and thighs, and fatigue.
• Physical exam findings may include rapid heart rate, hand tremors, hyperreflexia, enlarged thyroid gland, moist fine skin, inability to sit still, lid lag, proptosis, and onycholysis.
• Thyroid storm is a life-threatening thyrotoxicosis, which is often the result of abrupt cessation of antithyroid drugs, surgical procedures, or exposure to iodine-containing contrast or radioactive iodine.
• There is a classification system for thyroid storm using a point scale based on body temperature, heart rate, signs of congestive heart failure, atrial fibrillation, central nervous system disturbance, and gastrointestinal-hepatic dysfunction.

Classifications for Hyperthyroidism

• According to the level of dysfunction within the H-P-T axis:
  • Primary hyperthyroidism: problem at the level of the thyroid gland itself
  • Secondary hyperthyroidism: problem at the level of the pituitary leading to overproduction of TSH
  • Tertiary hyperthyroidism: (no known instances)
• According to the type of process leading to high levels of thyroid hormone:
  • Ongoing thyroid hormone synthesis and release
  • Release of excessive amounts of pre-formed, stored thyroid hormone due to a destructive process, usually short-lived less than 3 months.

Disorders causing hyperthyroidism/thyrotoxicosis

• Graves' Disease:
  • Most common cause of hyperthyroidism
  • Caused by antibodies that bind to and activate TSH receptors, causing thyroid gland to overproduce thyroid hormone.
  • Antibodies mimic actions of TSH, but are not under negative feedback control.
  • Tends to run in families with other autoimmune conditions.
  • Has specific physical exam findings:
    • Uniformly enlarged thyroid gland/goiter +/- thyroid bruit
    • Thyroid ophthalmopathy: proptosis, stare, lid lag, redness, abnormal extraocular movements, tearing, periorbital edema.
      • Occurs in nearly 70% of patients if diagnosed by CT.
      • Clinically evident ophthalmopathy occurs in about 25% of patients.