HYPOTHYROIDISM

What is the thyroid?

The thyroid is a butterfly-shaped gland located in the front of the neck. It produces hormones that regulate the body's metabolic rate, and has major influences on various functions like heart rate, digestion, physical and mental growth, body temperature, and energy levels.

Hypothyroidism occurs when the thyroid gland fails to produce enough thyroid hormone. It is a common chronic disease. Symptoms may not be recognized for years, however, and is often mistaken for other illnesses, menopause, or aging. People are often unaware that they have the disease.

The brain normally controls the levels of thyroid hormone through the release of a chemical called TSH which stimulates the thyroid gland to produce more hormones.

What causes hypothyroidism?

Most cases of hypothyroidism occur when the gland no longer responds normally to TSH. Most often this is the result of Hashimoto's disease, or chronic thyroiditis. In this disease, the body's immune system attacks the thyroid as if it was a foreign body, and can potentially destroy the gland. The brain responds by increasing TSH levels to boost production. The thyroid is usually able to meet the body's needs for a while, but eventually the hormone levels fall.

Hypothyroidism more common in middle aged women, although it can affect anyone of any age. Newborn infants are tested for this at birth as the problem can lead to mental and physical abnormalities (cretinism). In children, hypothyroidism can slow growth.

Risk factors for hypothyroidism include obesity, high cholesterol, diabetes, autoimmune diseases such as lupus and rheumatoid arthritis, and a family history of thyroid disease.

Other causes of hypothyroidism include radiation treatments, surgical removal of the gland, medicines such as lithium, and other disorders.

SYMPTOMS
  • Fatigue
  • Decreased heart rate
  • Progressive hearing loss
  • Weight gain
  • Problems with memory and concentration
  • Depression
  • Goiter (enlarged thyroid gland)
  • Muscle pain, weakness, or cramps
  • Loss of interest in sex
  • Numb, tingling hands
  • Dry skin
  • Swollen eyelids
  • Dryness, loss, or premature graying of hair
  • Extreme sensitivity to cold
  • Constipation
  • Irregular menstrual periods
  • Hoarse voice
  • Large tongue, facial swelling
It's important to see a doctor if any of these symptoms appear.

Diagnosis

Diagnosis of hypothyroidism is based on symptoms, medical history, physical exam, and blood testing. A blood test to check the thyroid-stimulating hormone (TSH) level is often used to screen for problems. Though accurate, the TSH may not detect mild cases and can be misleading, so further labs may be necessary. Sometimes special scans are used.

Treatment

Natural or synthetic thyroid hormones are used to restore normal levels, usually determined by achieving a normal TSH. Synthetic hormones are most effective, but it may take several months to determine the proper dose. Patients often start to feel better within 48 hours, and symptoms will return if they stop taking the medication. Hypothyroidism is a chronic condition, which means that it can be treated, but not cured. Patients should expect to continue the medicine for the rest of their lives, though the required dose might change from time to time.

Most doctors prescribe a medicine called levothyroxine. Most people should expect to take the medication for the rest of their lives. As many factors can affect how much replacement hormone is needed, regular TSH tests are recommended.

Alternative treatment

Other treatments are aimed at strengthening the thyroid, but do NOT eliminate the need for thyroid hormone medications. Herbal remedies to improve thyroid function and relieve symptoms of hypothyroidism include bladder wrack (Fucus vesiculosus), which can be taken in capsule form or as a tea. Eliminating cabbage, peaches, radishes, soybeans, peanuts, and spinach may improved thyroid function.

Prognosis

Thyroid hormone replacement therapy generally maintains normal thyroid hormone levels unless treatment is interrupted or discontinued.

Prevention

Primary hypothyroidism can't be prevented, but routine screening of adults could detect the disease in its early stages and prevent complications.

Adapted from American Academy of Family Physicians