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. Laboratory studies are important in the workup of thyroiditis, while thyroid ultrasonography is useful in revealing abscess formation in patients with acute thyroiditis. Moreover, acute thyroiditis requires immediate parenteral antibiotic therapy before abscess formation begins.
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.
Signs and symptoms of thyroiditis
Characteristics of acute thyroiditis include the following
The patient may have a fever of 38-40°C
Acute illness may be evident
Neck tenderness is present, and the swollen thyroid gland is tender; the swelling and tenderness may be unilateral; erythemas develop over the gland, and regional lymphadenopathy may develop as the disease progresses; abscess formation may occur
Characteristics of subacute thyroiditis include the following:
The patient may have signs of systemic illness, such as low-grade fever and weakness
Signs of hyperthyroidism, including increased pulse rate, widened pulse pressure, fidgeting, tremor, nervousness, tongue fasciculations, brisk reflexes (possibly with clonus), weight loss, and warm, moist skin, may be present
The thyroid gland may be enlarged and tender, with tenderness exacerbated by neck extension
Characteristics of chronic autoimmune thyroiditis include the following:
Initially, an enlarged, lumpy, bumpy, and nontender thyroid is often present; the gland may not be enlarged, particularly in children who have profound hypothyroidism
Signs of hypothyroidism include slow growth rate; weight gain; slow pulse; cold, dry skin; coarse hair and facial features; edema; and delayed relaxation of the deep tendon reflexes
Signs of hyperthyroidism are occasionally present early in the disease
Diagnosis of thyroiditis
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.
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.