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What is hypothyroidism?

The thyroid gland is a butterfly-shaped organ found in the center of the neck, below the Adam's apple. It creates and stores hormones that control the body's heart rate, blood pressure, and metabolism (how the body makes energy from food). Hypothyroidism is a condition in which the thyroid gland produces fewer hormones than the body needs.

What are the signs of hypothyroidism?

In hypothyroidism, the body's systems slow down. This can cause:

  • Feeling tired and weak
  • Feeling chilly, even when others with you feel warm
  • Puffiness (myxedema), especially around the face and eyes
  • Slow heart rate
  • Constipation
  • Decreased appetite
  • Muscle cramps
  • Irregular or absent menstrual periods in female patients
  • Shortness of breath
  • Depression
  • Dry skin
  • Hair thinning, or hair loss

Hypothyroidism, if not treated, can become a very dangerous condition.

What causes hypothyroidism?

The most common cause of hypothyroidism in adults is Hashimoto's thyroiditis, which causes long-term inflammation of the thyroid gland. This disease damages the thyroid tissue so the gland can't work properly.

Other causes of hypothyroidism include:

  • The failure of the pituitary gland to adequately stimulate the thyroid to produce its hormones (hypopituitarism)
  • Congenital (present at birth) defects
  • Treatment for hyperthyroidism (excess thyroid hormones), including removal of the thyroid gland and radiation therapy
  • Viral infections
  • Reactions to certain medications

How does my doctor tell if I have hypothyroidism?

In addition to a physical examination, your doctor will want to perform a TSH blood test. In an effort to get the thyroid working properly, the pituitary gland produces high levels of TSH, a hormone that usually stimulates the thyroid. In hypothyroidism, TSH is not used by the thyroid, and its levels remain high in the blood.

How is hypothyroidism treated?

Thyroid hormone replacement therapy treats hypothyroidism by giving you the hormones that your thyroid is not producing.

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