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Hashimoto Disease

January 24, 2022

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Hashimoto disease, also known as Hashimoto's thyroiditis, is an autoimmune disease. It is more common in women than in men, and also more common as people age. Hashimoto disease is the most common cause of hypothyroidism in iodine-sufficient areas of the world, including the United States. 

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Autoimmune diseases occur when the body’s immune system starts to make antibodies which target areas of the body that they should not. Usually, the immune system is supposed to protect our bodies and help fight disease. The antibodies in Hashimoto disease, called thyroid peroxidase antibodies (TPO), target the thyroid gland. Subsequently, the thyroid becomes inflamed and is not able to make thyroid hormones as efficiently as it should. This results in low thyroid hormone levels, and we call this condition hypothyroidism. In some people, this inflammation of the thyroid can cause it to becomes enlarged (called goiter) and in others, the gland can shrink down. The hypothyroidism caused by Hashimoto disease progresses slowly over months to years.

We don’t know exactly what causes Hashimoto disease to develop in an individual at a particular time. Both genetics and environmental factors play a role, and Hashimoto disease does run in families.

Your doctor will perform a physical examination and order blood tests to measure your hormone levels; we collectively call these labs thyroid function tests (TFTs) – TSH, free T4, total T3. 

TSH test:  TSH is hormone released from your pituitary gland when there is not enough thyroid hormone in the system. TSH will be high if there is not enough thyroid hormone in the system. Normal ranges for TSH vary lab by lab and are dependent on age (TSH normally rises as we age).

Free T4 and total T3 test: T3 and T4 are thyroid hormones. A low level of free T4 and/or T3 test also suggest hypothyroidism. 

Thyroid Peroxidase (anti-TPO) Antibody Blood Test: This test detects the presence of antibodies directed against the thyroid. Most people with Hashimoto disease have these antibodies, but people whose hypothyroidism is caused by other conditions may not. TPO antibodies may also be present in normal people without hypothyroidism. 

Possible symptoms include: 

  • Enlarged thyroid (or goiter) 
  • Trouble swallowing or breathing due to enlarged thyroid  
  • Intolerance to cold 
  • Mild weight gain 
  • Fatigue 
  • Constipation 
  • Dry skin 
  • Hair loss 
  • Heavy and irregular menses 
  • Infertility or miscarriage 
  • Difficulty concentrating or thinking 
  • Decreased libido 

If left untreated, hypothyroidism caused by Hashimoto disease can lead to serious complications: 

  • Goiter, which can interfere with swallowing or breathing. 
  • Heart problems such as enlarged heart or heart failure. 
  • Mental health issues such as depression, decreased sexual desire, slowed mental functioning. 
  • Myxedema coma, a rare life-threatening condition that can result from long-term untreated hypothyroidism. Myxedema coma requires immediate emergency treatment. 
  • Birth defects. Babies born to women with untreated hypothyroidism are more likely to be stillborn or premature. They may also have lower IQ (intelligence) later in life due to underdevelopment of the brain while in the womb. 

Anyone can develop Hashimoto disease, and symptoms vary from person to person; but it occurs more often in women and those with a family history of thyroid disease. It also occurs more often as people get older. People with other autoimmune disorders are more likely to develop Hashimoto disease. 

Not everyone with Hashimoto disease has hypothyroidism. If you have positive TPO antibodies but thyroid hormone levels are normal, then observation with repeated thyroid function tests is often recommended.  If thyroid hormone levels are low, then treatment often involves thyroid hormone replacement therapy.  If you have symptoms of hypothyroidism but the thyroid function tests are normal, then it is most likely that the symptoms are coming from a different cause than the thyroid. The most effective treatment is a synthetic (man-made) T4 medicine called levothyroxine.

Levothyroxine is identical to the T4 produced by your body. A daily pill can restore normal levels of thyroid hormone and TSH in your bloodstream and make your thyroid function normal. You will probably need to take this medicine daily for life, but your dose may need to be adjusted from time to time related to multiple aspects such as your weight, if you remember to take medication, and how it is spaced out from food and other medication. To maintain consistent thyroid hormone levels in your blood, you should always take the same brand since not all medicines are the sameCalcium supplements, iron supplements, or anti-acid medications should be spaced several hours apart from your thyroid medication, as these can interfere with absorption of thyroid hormone.

People are not routinely screened for hypothyroidism. However, if you are at risk for thyroid disease and are thinking about getting pregnant, you should be tested. Hypothyroidism is easily treated, and you can protect your child from birth defects.

  • Do my symptoms mean I have hypothyroidism? 
  • How can I tell if my hypothyroidism is caused by Hashimoto's disease? 
  • What should I do about my hypothyroidism if I want to get pregnant?  
  • What medicines do I need? When should I take them? What medications or supplements should I avoid with my thyroid medications? 
  • How often should I see my doctor or get testing of my thyroid? 
  • What else can I do to stay healthy?  
  • Should I see an endocrinologist for my care? 

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