Hashimoto's Disease- How it affects the thyroid gland!

Hashimoto's Disease Overview

Hashimoto's thyroiditis, or Hashimoto's disease, is a disorder that affects the thyroid gland. Hashimoto's thyroiditis is also known as chronic autoimmune thyroiditis and chronic lymphocytic thyroiditis.

The name Hashimoto's thyroiditis comes from the pathologist who in 1912 first described the microscopic features of the disease. Hashimoto's disease is the most common cause of hypothyroidism in iodine-sufficient areas throughout the world such as the United States. In general, there is a gradual loss of thyroid function, often accompanied by enlargement of the thyroid gland, also known as a goiter. Hashimoto's disease is most common in middle-aged women and tends to run in families.

As a brief background, the thyroid is responsible for producing hormones that exert control over and participate in a number of metabolic functions such as temperature and heart rate regulation, and metabolism.

Picture of the Thyroid Gland

Hashimoto's Disease Causes

The cause of Hashimoto's is thought to be a combination of a genetic predisposition along with an environmental trigger that starts the process of autoimmune destruction. What the trigger actually is remains unknown. Additional factors, including heredity, gender, and age, also play a role in developing this disorder.

Normally, the immune system acts to protect against viruses, bacteria, and foreign substances (antigens) that invade the body. In conditions of autoimmune disease, the immune system mistakenly attacks parts of the body itself. In the case of Hashimoto's disease, the immune system attacks the thyroid gland. Theautoimmune process causes inflammation of the thyroid gland (thyroiditis), resulting in an impaired ability of the thyroid gland to produce hormones, leading to hypothyroidism. The pituitary gland responds by increasing TSH and attempting to stimulate the thyroid gland to produce more thyroid hormones. This can cause growth of the gland, or a goiter.

Hashimoto's Disease Symptoms and Signs

The signs and symptoms of Hashimoto's disease are the same as those of hypothyroidism. The disease is slow to progress, and it may take years for true hypothyroidism to develop.

The signs and symptoms of hypothyroidism vary widely, depending on the severity of hormone deficiency. Some of the complaints experienced by those with hypothyroidism include:

• fatigue,
  
• mental fogginess and forgetfulness,
  
• feeling excessively cold,
  
• constipation,
  
• dry skin,
  
• fluid retention,
  
• non-specific aches and stiffness in muscles and joints,
  
• excessive or prolonged menstrual bleeding(menorrhagia), and
  
• depression

These signs and symptoms can increase in severity as the condition worsens.

Complications of Hashimoto's disease

The complications of Hashimoto's disease are the same as those of an underactive thyroid gland. The complications may be local and related to the structural changes in the gland or systemic (body-wide) and related to the decrease in hormone production.

Local complications

Goiter: As described above, the pituitary will try to stimulate production of thyroid hormone in an underactive thyroid gland affected by Hashimoto's disease. This may cause the gland to become enlarged. Unlike a thyroid nodule, in which only a part of the gland is enlarged, in this case the entire gland enlarges- a condition called goiter. Goiterous glands are usually no more than a cosmetic nuisance. However, in extreme cases, growth of the gland may cause impingement on the esophagus or the trachea, impairing swallowing and breathing, respectively.

Systemic complications

Cardiac: Prolonged hypothyroidism that may result from untreated Hashimoto's disease also may be associated with an increased risk of heart disease. The heart disease may be directly related to hypothyroid effects on the heart, causing changes in contraction and rhythm that may lead to subsequent heart failure. There may also be indirect influences, such as hypercholesterolemia (an increase in "bad" cholesterol is often seen with hypothyroidism).

Psychiatric: Depression may occur early in Hashimoto's disease and if underlying depression exists, the addition of Hashimoto's may worsen the condition. Patients may complain of mental fogginess or slowing of reaction times, and a decrease in sexual desire is often observed.

In its severest form, hypothyroidism may result in a rare life-threatening condition called myxedema or myxedema coma. There is mental slowing, profound lethargy, and ultimately coma. This is a life-threatening emergency.

It is important to remember that during states of hypothyroidism, the metabolism of drugs slows down. Thus, a very small dose of a sedative may have profound results. Unintentional overdosing becomes a very real possibility.

Hashimoto's Disease and Pregnancy

Babies born to women who have uncontrolled hypothyroidism during their pregnancy may have a greater risk of birth defects than babies born to mothers with normal thyroid function. There may be a direct link with congenital defects such as cleft palate and certain brain and kidney anomalies. Data suggests that over the long term, these children may also have a higher likelihood of intellectual and developmental problems. Intervening early in pregnancy with thyroid hormone replacement may have significant benefits. Interestingly, there is also recent data to suggest that the presence of thyroid autoantibodies, such as those seen in Hashimoto's disease, may reduce the chance of conception.

Hashimoto's Disease Diagnosis

Most people are diagnosed with Hashimoto's disease after presenting to their physician with typical symptoms of hypothyroidism noted above. Some patients are diagnosed without symptoms on a routine screen, and others are diagnosed after a family member is found to have the disease and concern is raised.

The diagnosis is made based on the results of blood tests that measure levels of thyroid hormone and thyroid-stimulating hormone (TSH). These blood tests confirm hypothyroidism, but the addition of positive autoantibody tests further points to Hashimoto's disease as the underlying cause. Antibodies can be measured in the blood, and the presence of antibodies against thyroid peroxidase (TPO) is usually seen in Hashimoto's thyroiditis.

Hashimoto's Disease Treatment

If there is no evidence of hormone deficiency and only antibodies tests are positive, the use of medications is one that must be discussed in detail by the patient and doctor. Other medical conditions, patient preference, and the presence of symptoms are all taken into consideration.