Thyroiditis

Updated: Apr 28, 2017
  • Author: Robert P Hoffman, MD; Chief Editor: Sasigarn A Bowden, MD  more...
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Overview

Practice Essentials

The broad category of thyroiditis includes the following inflammatory diseases of the thyroid gland: (1) acute suppurative thyroiditis, which is due to bacterial infection; (2) subacute thyroiditis, which results from a viral infection of the gland; and (3) chronic thyroiditis, which is usually autoimmune in nature. In childhood, chronic thyroiditis is the most common of these 3 types. The second form of thyroiditis, Riedel struma, is rare in children. Secondary thyroiditis may be due to the administration of amiodarone to treat cardiac arrhythmias or the administration of interferon-alpha to treat viral diseases.

Three multinuclear, giant cell granulomas observed Three multinuclear, giant cell granulomas observed in a fine-needle aspiration biopsy of the thyroid; from a patient with thyrotoxicosis from lymphocytic or subacute granulomatous thyroiditis.

Diagnosis

Laboratory test results vary according to the type of thyroiditis, as follows:

  • Acute thyroiditis - Laboratory abnormalities in acute thyroiditis reflect the acute systemic illness; findings include leukocytosis with a left shift and an increased sedimentation rate; thyroid function test results are within the reference range
  • Subacute thyroiditis - Initially, the thyroid-stimulating hormone (TSH) level is suppressed, and the free thyroxine (T4) level is increased; as the disorder progresses, transient or sometimes permanent hypothyroidism may develop
  • Chronic thyroiditis - TSH levels are increased in children with subclinical and overt hypothyroidism; free T4 levels are within the reference range in the former and low in the latter; in children with hyperthyroidism, TSH levels are suppressed; many children have normal thyroid function and normal TSH levels; antithyroid peroxidase (antithyrocellular, antimicrosomal) antibody levels elevated above the reference range are the most sensitive indicator of thyroid autoimmunity

Radioactive iodine thyroid scanning is helpful in patients with hyperthyroidism who are thought to have subacute thyroiditis, because the extremely low uptake is consistent with the thyrocellular destruction in progress. Thyroid ultrasonography is useful in revealing abscess formation in patients with acute thyroiditis.

In patients with acute thyroiditis, fine-needle aspiration can be used to obtain material for culture, enabling appropriate antibiotic therapy.

Management

Medical care in thyroiditis includes the following:

  • Acute thyroiditis - Acute thyroiditis requires immediate parenteral antibiotic therapy before abscess formation begins; for initial antibiotic therapy, administer penicillin or ampicillin to cover gram-positive cocci and the anaerobes that are the usual causes of the disease
  • Subacute thyroiditis - Subacute thyroiditis is self-limiting; therefore, the goals of treatment are to relieve discomfort and control abnormal thyroid function
  • Chronic autoimmune thyroiditis - Treatment for chronic autoimmune thyroiditis depends on the results of the thyroid function tests; patients with overt hypothyroidism who have high TSH and low free T4 levels require treatment with levothyroxine; the treatment of subclinical hypothyroidism in patients with elevated TSH and normal free T4 levels is controversial; these children may enter a remission phase and may not have permanent hypothyroidism (this appears to be a minority of subjects); most pediatric endocrinologists recommend treatment of subclinical hypothyroidism during childhood to ensure normal growth and development; if thyroxine administration may not be permanently required, treatment may be stopped once the patient has completed pubertal development, and thyroid function then can be reassessed

In acute thyroiditis, surgery may be necessary to drain the abscess and to correct the developmental abnormality responsible for the condition.

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Pathophysiology

Acute suppurative thyroiditis is rare in childhood because the thyroid is remarkably resistant to hematogenously spread infection. Most cases of acute thyroiditis involve the left lobe of the thyroid and are associated with a developmental abnormality of thyroid migration and the persistence of a pyriform sinus from the pharynx to the thyroid capsule. The usual organisms responsible include Staphylococcus aureus, Streptococcus hemolyticus, and pneumococcus. Other aerobic or anaerobic bacteria may also be involved.

Subacute thyroiditis is generally thought to be due to viral processes and usually follows a prodromal viral illness. Various viral illnesses may precede the disease, including mumps, measles, influenza, infectious mononucleosis, adenoviral or Coxsackievirus infections, myocarditis, or the common cold. Other illnesses or situations associated with subacute thyroiditis include catscratch fever, sarcoidosis, Q fever, malaria, emotional crisis, or dental work. The disease is more common in individuals with human leukocyte antigen (HLA)–Bw35.

Because chronic thyroiditis in children is usually due to an autoimmune process, it is HLA-associated, similar to other autoimmune endocrine diseases. The specific alleles in the atrophic and goitrous forms of the disease vary. The histologic disease picture varies, but lymphocytic thyroid infiltration is the hallmark of the disease and frequently obliterates much of the normal thyroid tissue. Follicular thyroid cells may be small or hyperplastic. The degree of fibrosis among patients also widely varies. Children usually have hyperplasia with minimal fibrosis. The blood contains autoantibodies to thyroid peroxidase and, frequently, autoantibodies to thyroglobulin. Autoimmune thyroiditis is also frequently part of the polyglandular autoimmune syndromes.

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Epidemiology

Frequency

United States

Studies in the United States and Western Europe report a prevalence of 1.2% in individuals aged 11-18 years. Approximately 25% of adults with type 1 diabetes have thyroiditis, about one half of whom have hypothyroidism. Approximately 10% of children with type 1 diabetes have antithyroid antibodies. Thirteen of 121 children with vitiligo were also found to have subsequent evidence of autoimmune thyroiditis. [1]  Similarly, a Korean study, by Bae et al, indicated that persons with vitiligo have an odds ratio for the autoimmune disease Hashimoto thyroiditis of 1.609. [2]

The disease is also more common in children with Down syndrome or Turner syndrome. However, a study by Vassilatou et al indicated that the risk of autoimmune thyroiditis is not increased in psoriatic patients with or without psoriatic arthritis, finding the prevalence of autoimmune thyroiditis to be 20.2% in psoriatic patients (n = 114) and 19.6% in controls (n = 286). [3]  This contrasts with a study by Kiguradze et al, which reported an odds ratio of 2.49 for Hashimoto thyroiditis in persons with psoriasis. [4]

Acute suppurative thyroiditis is rare in Western nations. Subacute thyroiditis is rare in childhood.

International

The prevalence of chronic autoimmune thyroiditis varies depending on screening procedures. A Greek study showed a prevalence of thyroid antibodies as high as 12.5% in some areas. Few data are available regarding the incidence of the various forms of thyroiditis in the non-Western world. Acute thyroiditis is more common in geographic areas where antibiotic use is less prevalent.

Mortality/Morbidity

Long-term morbidity or mortality from thyroiditis is uncommon. Patients with autoimmune thyroiditis frequently develop hypothyroidism and require lifelong treatment. Patients with subacute thyroiditis may briefly have hyperthyroidism but usually regain normal thyroid function. Patients with acute thyroiditis generally maintain normal thyroid function.

Sex

The pediatric male-to-female ratio for autoimmune thyroiditis ranges from 1:2 to 1:6. This is low when compared with the 90% female predominance in adults. [5, 6, 7]

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Prognosis

Acute thyroiditis

Recovery is usually complete, and thyroid function returns to normal.

Subacute thyroiditis

This self-limiting disease may last 2-7 months.

Chronic autoimmune thyroiditis

Permanent hypothyroidism is the main complication. Approximately 20% of children with subclinical hypothyroidism enter remission and become euthyroidism. [7]

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