CLINICAL DIABETES
VOL. 18 NO. 1 Winter 2000

PATIENT INFORMATION

Thyroid Disorders

The thyroid is a butterfly-shaped gland in the neck. It has a lobe on each side of the Adam's apple with a thin ridge of tissue between the lobes.

The two major thyroid hormones are thyroxine (T4) and triiodothyronine (T3). The thyroid produces T4 when the pituitary gland in the brain releases thyroid-stimulating hormone (TSH). Almost all of T3 is made from T4 after it is released by the thyroid gland, but a small amount of T3 is produced directly by the thyroid gland.

T3 and T4 help control how the body uses food for energy (metabolism). In children, these hormones are needed for normal growth and development. In adults, they are vital in maintaining many normal body functions.

Thyroid disorders can result when the thyroid produces too much thyroid hormone (hyperthyroidism) or when it does not produce enough (hypothyroidism). Hypothyroidism is by far the most common thyroid disorder, affecting 4 million people in the United States. The most common cause is autoimmune thyroid disease, in which the body mistakes the thyroid gland for a foreign body and produces antibodies to destroy it.

You are more likely to develop a thyroid disorder if you:

  • Are over age 50. (Older adults, particularly women, are more likely to develop hypothyroidism.)
  • Are female. (Women are 5 times more likely to develop hypothyroidism than are men.)
  • Have a family history of thyroid disorders.
  • Have another autoimmune disorder, such as type 1 diabetes.
  • Have had thyroid surgery.
  • Have been exposed to radiation, especially irradiation to the neck
  • Have been treated for a thyroid problem with radioactive iodine.
  • Are iodine deficient (rare in the United States).
  • Take in too much iodine (in food or drugs).
  • Take drugs that can slow thyroid function, particularly lithium carbonate (used to treat a form of depression called bipolar disorder) or amiodarone (prescribed to treat heart

The symptoms of thyroid disorder are listed below. But because the symptoms are various and may be caused by other medical problems, identifying thyroid disorders based on symptoms can be difficult. The most reliable way to diagnose a thyroid disorder is by a simple blood test known as the TSH assay.

  Symptoms of Hypothyroidism

  • Fatigue
  • Depression
  • Sensitivity to cold
  • Dry and itchy skin
  • Constipation
  • Muscle cramps
  • Facial puffiness
  • Increased menstrual flow in women
  • Possible decrease in insulin requirement for people with diabetes

Symptoms of Hyperthyroidism

  • Nervousness
  • Irritability
  • Weight loss despite increased appetite
  • Sensitivity to heat
  • Increased perspiration
  • Shakiness
  • Insomnia
  • Fine brittle hair
  • Itchy skin
  • Fast heart rate
  • Decreased exercise tolerance
  • Muscle weakness
  • Possible worsening of blood glucose control and increased insulin requirement for people with diabetes

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