Hashimoto's vs. Hypothyroidism: What's the Difference?

A Look at Autoimmune Thyroid Disease and Underactive Thyroid Conditions

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What is the difference between Hashimoto's thyroiditis and hypothyroidism? This common question can be confusing to even veteran thyroid patients. 

Let's clear up the main difference: Hashimoto's thyroiditis is a disease; hypothyroidism is a condition. In the United States, hypothyroidism is most commonly caused by Hashimoto's thyroiditis, but the two terms are not interchangeable. Here is more information to help understand the difference.

Overview

Hashimoto's thyroiditis is an autoimmune disease that affects your thyroid gland. It is sometimes known as Hashimoto's disease, autoimmune thyroiditis, or chronic lymphocytic thyroiditis. In Hashimoto's, antibodies react against proteins in your thyroid gland, causing gradual destruction of the gland itself, and making it unable to produce the thyroid hormones your body needs.

Diagnosis

Hashimoto's disease is typically diagnosed by clinical examination that demonstrates one or more of the following findings:

  • Enlargement of your thyroid, known as a goiter
  • High levels of antibodies against thyroglobulin (TG) and thyroid peroxidase (TPO), detected via blood test
  • Fine needle aspiration of your thyroid (also known as a needle biopsy), which shows lymphocytes and macrophages
  • A radioactive uptake scan, which would show diffuse uptake in your enlarged thyroid gland
  • Ultrasound, which would show an enlarged thyroid gland

    Symptoms 

    If you have Hashimoto's thyroiditis, you may have no demonstrable symptoms. Many Hashimoto's patients experience thyroid enlargement, however, known as a goiter. Your goiter can range from slight enlargement, which may have no other symptoms, to a substantial increase in size that is symptomatic.

    If you have Hashimoto's, especially with a large goiter, you may feel discomfort in the neck area. Scarves or neckties may feel uncomfortable. Your neck may feel swollen or uncomfortably enlarged, even sore. Sometimes your neck and/or throat is sore or tender. Less commonly, swallowing or even breathing can become difficult if a goiter is blocking your windpipe or esophagus.

    Hashimoto's typically involves a slow but steady destruction of your gland that eventually results in the thyroid's inability to produce sufficient thyroid hormone—the condition known as hypothyroidism. Along the way, however, there can be periods where your thyroid sputters back to life, even causing temporary hyperthyroidism, then a return to hypothyroidism. This cycling back and forth between hypothyroidism and hyperthyroidism is characteristic of Hashimoto's disease. So, for example, periods of anxiety/insomnia/diarrhea/weight loss may be followed by periods of depression/fatigue/constipation/weight gain.

    In some cases, the onset of Hashimoto's and elevation of antibodies will be accompanied by a variety of symptoms, including anxiety, difficulty sleeping, fatigue, weight changes, depression, hair loss, muscle/joint aches and pains, and fertility problems, among others.

    Ultimately, however, the autoimmune attack on the thyroid typically makes the gland slowly less able to function, and eventually, the thyroid becomes underactive. When hypothyroidism itself can be measured by blood tests, many practitioners will finally diagnose the hypothyroidism, and treat the patient with thyroid hormone replacement drugs.

    Preventive Treatment 

    If your goiter causes difficulty swallowing or breathing or is a cosmetic problem, then thyroid hormone replacement drugs (i.e., levothyroxine or natural desiccated thyroid) will usually be given to help shrink the thyroid. If drug treatment does not work, or the goiter is too invasive, then surgery to remove all or part of your thyroid may be recommended.

    Except in the case of a goiter, most endocrinologists and conventional physicians will not treat your Hashimoto's disease, as diagnosed by elevated antibody levels, unless other thyroid function tests such as TSH are outside the normal reference range.

    There are, however, some endocrinologists, as well as holistic MDs, osteopaths, and other practitioners, who believe that Hashimoto's disease—as confirmed by the presence of thyroid antibodies—along with symptoms, are enough to warrant treating you with low doses of thyroid hormone replacement medication.

    The practice of treating patients who have Hashimoto's thyroiditis but normal range thyroid function tests is by several studies that have found that levothyroxine treatment for patients who had Hashimoto's thyroiditis but whose TSH had not yet elevated beyond normal range (the term for this is "euthyroid") could reduce the likelihood and degree of their autoimmune disease worsening.

    In the study of patients with euthyroid Hashimoto's thyroiditis (normal range TSH, but elevated antibodies), half of the patients were treated with levothyroxine for a year, the other half were not treated. After one year of therapy with levothyroxine, the antibody levels and lymphocytes (evidence of inflammation) decreased significantly only in the group receiving the medication. Among the untreated group, the antibody levels rose or remained the same.

    The researchers concluded that preventive treatment of normal TSH range patients with Hashimoto's thyroiditis reduced the various markers of autoimmune thyroiditis, and speculated that that such treatment might even be able to stop the progression of Hashimoto's, or perhaps even prevent progression to overt hypothyroidism.

    Selenium

    In the area of nutrition, promising findings from a number of research studies have pointed to the value of the mineral selenium in helping to combat autoimmune thyroid disease.

    Some studies have shown that selenium supplementation at the typically safe dose of 200 mcg per day can lower elevated thyroid antibody levels to normal, or reduce them significantly, therefore warding off development of full autoimmune thyroid disease, and resulting hypothyroidism.

    Hypothyroidism

    Many people with Hashimoto's thyroiditis end up hypothyroid, the situation where the thyroid is either underactive or, eventually, totally unable to function.

    Hashimoto's thyroiditis is the leading cause of hypothyroidism in the U.S. The other causes of hypothyroidism include, among others:

    • Graves' disease and hyperthyroidism treatments including radioactive iodine treatment (RAI) and surgery
    • thyroid cancer treatment, including surgery to remove all or part of the thyroid
    • surgical removal of all or part of the thyroid as a treatment for goiter or nodules
    • use of antithyroid drugs (such as Tapazole or PTU) to reduce thyroid activity
    • use of certain drugs, such as lithium

    The diagnosis and treatment of hypothyroidism itself is a detailed topic, and you can read more about it here at the site:

    Sources:

    Beckett GJ, Arthur JR. "Selenium and endocrine systems." J Endocrinol. 2005 Mar;184(3):455-65.

    Braverman, L, Cooper D. Werner & Ingbar's The Thyroid, 10th Edition. WLL/Wolters Kluwer; 2012.

    Garber, J, Cobin, R, Gharib, H, et. al. "Clinical Practice Guidelines for Hypothyroidism in Adults: Cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association." Endocrine Practice. Vol 18 No. 6 November/December 2012.

    Thyroid, 2001 Mar;11(3):249-55, "One-year prophylactic treatment of euthyroid Hashimoto's thyroiditis patients with levothyroxine: is there a benefit?"

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