Hypothyroidism

Chapter 21 HYPOTHYROIDISM



Kathleen Dor


Hypothyroidism usually results from decreased thyroid hormone production and secretion by the thyroid gland. Hypothyroidism can be either primary or central. Central hypothyroidism involves either the pituitary gland (secondary hypothyroidism) or the hypothalamus (tertiary hypothyroidism). In the United States, the most common cause of hypothyroidism is chronic autoimmune thyroiditis.


Hypothyroidism is far more common in women and in the elderly than in other populations. In fact, about 2% to 3% of older women have hypothyroidism. Other risk factors include the presence of thyroid peroxidase antibodies and a high normal level of TSH.


Untreated hypothyroidism can result in decreased cardiac output, memory loss, infertility, and sleep apnea. The American Academy of Family Physicians recommends screening for hypothyroidism in patients 60 years of age or older and in patients with symptoms of hypothyroidism, a family history of thyroid disease, a history of autoimmune disease, or type 1 diabetes.


Myxedema coma refers to severe complications of hypothyroidism, involving hypothermia and stupor or coma. Myxedema coma can be precipitated by mild illnesses, exposure to cold, myocardial infarction, and medications that affect the central nervous system.


During pregnancy, there is a greater requirement of thyroid hormone because of increased maternal use, as well as transportation of thyroid hormone across the placenta. Some women who were euthyroid before pregnancy become hypothyroid during pregnancy. It is very important that women be treated adequately for hypothyroidism during pregnancy to avoid complications such as miscarriage, preeclampsia, preterm labor, and postpartum hemorrhage.



Medications That Can Cause Hypothyroidism




Amiodarone


Ethionamide


Interferon-α


Interleukin-2


Iodine excess


Lithium


Methimazole


Propylthiouracil


Sulfonamides



Causes of Hypothyroidism



Primary Hypothyroidism



Agenesis and dysgenesis of the thyroid gland


External irradiation


Hashimoto disease (chronic autoimmune thyroiditis)


Infections


• Mycobacterium tuberculosis

• Pneumocystis carinii

Infiltrative disorders


• Amyloidosis

• Hemochromatosis

• Leukemia

• Lymphoma

• Sarcoidosis

• Scleroderma

Invasive fibrous thyroiditis


Iodine deficiency


Medications


Postpartum thyroiditis


Radioactive iodine therapy

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Jun 4, 2016 | Posted by in GYNECOLOGY | Comments Off on Hypothyroidism

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