Inflammation of the thyroid characterized by a triphasic course of transient thyrotoxicosis, followed by hypothyroidism, followed by return to euthyroidism.
The thyrotoxic phase is due to thyroid follicular damage and release of preformed hormone, and is characterized by very low thyroid uptake on nuclear scan and elevated ESR or CRP.
Moderate-to-severe thyroid pain and tenderness, which may be migratory and affect different areas of the gland at different times, is typical of the thyrotoxic phase. Thyroid is often enlarged, firm, and tender to palpation.
Ultrasound of the thyroid shows areas of hypoechoic echotexture with decreased or normal vascular flow by Doppler.
The condition is self-limited, and no specific therapy is generally necessary. Nonsteroidal anti-inflammatory drugs and beta-blockers may be used for symptoms. Some patients with severe symptoms may also require corticosteroids, opioid analgesics, or potassium iodide or iopanoic acid to reduce the conversion of T4 to the more biologically active form of thyroid hormone, T3.
Subacute granulomatous thyroiditis is a self-limited inflammation of the thyroid gland. It is associated with a triphasic clinical course that lasts for a few weeks to many months, characterized by transient thyrotoxicosis, hypothyroidism, and then a return to normal thyroid function in >90% of patients. The initial thyrotoxic phase is associated with thyroid pain, high serum thyroid hormone levels with a low radioiodine uptake, elevated ESR, elevated CRP, and a systemic illness similar to influenza, with fever, myalgia, and malaise.
History and exam
Key diagnostic factors
- neck pain
- tender, firm, enlarged thyroid
Other diagnostic factors
- recent viral infection
- heat intolerance
- viral infection
- HLA-Bw35 and B35
1st investigations to order
- thyroid-stimulating hormone (TSH)
- total T4, total T3, T3 resin uptake, free thyroxine index
- T3:T4 ratio
- radioactive iodine uptake
- antithyroid antibodies (thyroid peroxidase antibodies)
Investigations to consider
- fine needle aspiration biopsy
- ultrasonography of thyroid
- salivary CRP
- Graves disease
- Infectious, suppurative, or acute thyroiditis
- Toxic multinodular goiter
- 2017 guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and the postpartum
- 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis
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