HASHIMOTO'S THYROIDITIS

Mauro Czepielewski, MD., Ph.D. in Endocrinology – São Paulo State University School of Medicine (UNIFESP). Vice-Director of the State University Rio Grande do Sul School of Medicine (UFRGS). Associate Professor – Internal Medicine Department/UFRGS.

Alternative names:

Autoimmune thyroiditis; chronic lymphocytic thyroiditis; thyroid inflammation

What is it?

It’s an autoimmune condition in which the organism itself produces antibodies against the thyroid gland leading to a chronic inflammation that may result in the gland’s enlargement (goiter) and a decrease in its functional activity (hypothyroidism).

As this is an autoimmune disease, it may be associated to further diseases with these characteristics, involving other glands (suprarenal, parathyroid, pancreas, gonads) or other organs such as the skin and liver mainly (see Hypothyroidism and Adrenal Insufficiency on this site).

It’s the most common cause of thyroid enlargement in women aged between 20 and 40 years, especially leading to the occurrence of diffuse goiter.

How does it develop?

The organism itself develops antibodies against the thyroid gland.

This situation occurs more frequently to women and people presenting some genetic predisposition, as the disease attacks several individuals of the same family.

Usually, the antibodies are against enzymes present in the gland (antimicrosomal and antithyroperoxidase antibodies) or against thyroglobulin, which is one of the most important proteins existent in the thyroid gland.

As the condition has autoimmune characteristics, involvement of other glands may take place, characterizing an autoimmune polyglandular insufficiency.

This set of alterations has two types:
 

Type I

Occurs more often in childhood, the patient presents with the adrenal and parathyroid glands, gonads and red blood cell production (anemia) involved.

Type II

The patient presents with Hashimoto’s Thyroiditis, diabetes mellitus, involvement of gonads and skin (vitiligo).

What does one experience?

Hashimoto’s thyroiditis patients can present local and general symptoms. Local symptoms are enlargement of the thyroid gland and mild local pain. The enlargement is designated goiter, which shows involvement of the entire gland in these cases, leading to diffuse goiter.

Pain is a symptom that seldom occurs, being generally of low intensity and observed on the neck’s lower region.

In a situation where the patient presents a painful condition of significant intensity that has appeared recently (a few days ago), another form of thyroiditis must be suspected – subacute thyroiditis. This disease is an inflammatory process of viral origin that rapidly affects the thyroid gland and is not associated with an autoimmune process. This form of thyroiditis is called subacute thyroiditis and has specific diagnosis and treatment.

The general symptoms result from a reduction in the functional activity of the thyroid gland, causing a clinical condition of primary hypothyroidism (see specific item on this site).

How does the doctor diagnose it?

The diagnosis is made through clinical history and suitable evaluation, including a comprehensive neck exam and study on signs and symptoms of the reduction in the thyroid gland’s functional activity (hypothyroidism). Based on an initial medical evaluation, the patient must undergo a TSH(thyroid-stimulating hormone) level assessment for thyroid function, occasionally using a T4 level test and study of antithyroid antibodies.

Amongst the antithyroid antibodies, one should prefer the assessment of antithyroperoxidase antibodies (anti-TPO antibodies); antimicrosomal and antithyroglobulin antibody tests can be conducted as well, despite their lower diagnostic sensitivity.

If the patient shows a significant enlargement of the thyroid gland and nodule, it’s useful to perform neck echography for thyroid features, which will determine whether there is only one or two nodules in the gland and what the characteristics of these nodules are.

If several nodules exist, but one of them is dominant, or if there’s a nodule in a diffuse goiter, this must be aspirated for a thorough diagnosis. The measurement of radioactive iodine capture or thyroiditis scintigraphy is an exam that presents a dubious indication in hypothyroidism and Hashimoto’s thyroiditis cases. These tests, which will demonstrate a reduction in iodine capture and difficulty identifying the thyroid gland, are laborious exams that use radioactivity, a reason why they’ve been set aside for this purpose.

How is it treated?

In cases where hypothyroidism occurs, specific treatment is indicated (see specific item on this site).

In cases where antibodies are positive and the thyroid function is normal, the patient must subject to a 6-month or yearly periodic medical and hormonal checkup and be medicated according to the disease evolution. The appearance of nodules or further associated diseases must be periodically evaluated.

It’s important to underscore that, although antibodies against the thyroid gland are detected, treatment with medications that may eventually reduce the antibodies isn’t indicated. Thus, individuals presenting with positive antibodies should not be medicated with cortisone (corticoids), anti-inflammatory or immunosuppressive drugs. The side effects from these drugs are greater than the benefits in these cases.

How is it prevented?

No preventive methods are known for Hashimoto’s thyroiditis.

It can, on the other hand, be early detected if we evaluate periodically risk patients. These patients are those that have some of the associated diseases or first-degree relatives carrying the disease. Patients already diagnosed who don’t present hypothyroidism yet must be checked for this condition periodically, preventing, therefore, the development of signs and symptoms of thyroid hormone deficiency.

 

 

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