Hypothyroidism - Causes

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Painless Postpartum Subacute Thyroiditis. Postpartum thyroiditis is an autoimmune condition that occurs in up to 10% of pregnant women and tends to develop between 4 and 12 months after delivery. In most cases, a woman develops a small, painless goiter. Although 80% of women with this condition have normal thyroid function within a year, some evidence suggests that half of women with this condition develop permanent hypothyroidism within 7 years. Women who have had recurrent episodes after previous pregnancies and women who have other autoimmune disorders are at higher risk fort his form of subacute thyroiditis. It is generally self-limiting and requires no therapy unless the hypothyroid phase is prolonged. In such cases, therapy may be thyroxine replacement may for a few months. A doctor will prescribe beta blockers if the hyperthyroid phase requires treatment.

Painless Sporadic, or Silent, Thyroiditis. This painless condition is very similar to postpartum thyroiditis except it can occur in both men and women and at any age. About 20% of patients with silent thyroiditis may develop chronic hypothyroidism. Treatment considerations are the same as for postpartum subacute thyroiditis.

Painful, or Granulomatous, Thyroiditis. This condition comes on suddenly with flu-like symptoms and severe neck pain and swelling. It generally occurs in the summer and is five times more common in women. It recurs in about 2% of patients and hypothyroidism persists in about 5%. Treatments typically include pain relievers and, in severe cases, corticosteroids.

Hyperthyroidism Treatments

Up to half or more of patients who receive radioactive iodide treatments for an overactive thyroid develop permanent hypothyroidism within a year of therapy. This is the standard treatment for Graves' disease, which is the most common form of hyperthyroidism, a condition caused by excessive secretion of thyroid hormones.

By the end of 5 years, about 65% of treated patients have developed hypothyroidism, after which the rate of this condition levels off to about 1% a year. Such patients need to take thyroid hormones for the rest of their lives. Other forms of treatment for overactive thyroid glands using either antithyroid drugs or surgery may also result in hypothyroidism.