Thyroiditis refers to a group of conditions in which the thyroid is inflamed and may be classified in three different ways:
1. Clinical symptoms: Painless or painful
2. Onset: Chronic, subacute or acute
3. Aetiology.
Most forms of thyroiditis are painless. De Quervain’s thyroiditis and acute suppurative thyroiditis are painful. Pain is a very helpful symptom in distinguishing between the different types of thyroiditis.
Most types of painless thyroiditis are autoimmune in nature. Hashimoto’s thyroiditis, subacute thyroiditis and Graves’ disease are all examples of thyroiditis with an autoimmune basis.
Chronic thyroiditis is Hashimoto’s thyroiditis, subacute thyroiditis is either postpartum or De Quervain’s, and acute thyroiditis is suppurative thyroiditis.
Many types of thyroiditis pass through four stages: thyrotoxicosis, euthyroid, hypothyroid and back to euthyroid. However, one or more of these stages may not occur. Thyrotoxicosis occurs when preformed thyroid hormones leak out into the circulation; therefore, antithyroid medication is not effective. Instead, beta blockers are used to control the symptoms of thyrotoxicosis. Graves’ disease is due to stimulation of the thyroid by thyroid stimulating antibodies causing over production of thyroid hormones (hyperthyroidism).
Anti-thyroid medication (carbimazole) is therefore used to treat Graves’ disease. If the decision is made to treat hypothyroidism it is treated with thyroxine at a dose of 1.6 microgram per kg per day. In elderly patients and patients with ischaemic heart disease thyroxine is started at a lower dose: 25 micrograms per day and titrated up every four to six weeks, depending on the results of blood tests (TSH and fT4).
Hashimoto’s thyroiditis (chronic lymphocytic thyroiditis)
Ninety-five percent of patients with Hashimoto’s thyroiditis are women, and it commonly presents in the 30–50-year-old age group. It is the most common cause of hypothyroidism. Because about 50% of people with Hashimoto’s thyroiditis eventually develop hypothyroidism, it is recommended to request annual thyroid function tests. Rarely, Hashimoto’s can present with thyrotoxicosis – Hashitoxicosis.
There is an increased incidence of lymphoma Understanding thyroiditis By Dr Francis Hall VOICES OF THE SECTOR VOICES OF THE SECTOR GP VOICE | NOVEMBER 2024 | PAGE 2 6 of the thyroid in people with Hashimoto’s. Most patients are thyroid antibody (thyroid peroxidase antibody) positive. Ultrasound scan shows an enlarged diffusely hypoechoic thyroid. Investigate any suspicious nodules with ultrasound-guided FNA. See the article on thyroid nodules in the June issue of GP Voice for more information.
Subacute thyroiditis (Postpartum thyroiditis)
This usually occurs 3–12 months postpartum. Sometimes it occurs sporadically. It presents as a small painless thyroid and symptoms of thyrotoxicosis (tachycardia, heat intolerance, nervousness, weight loss). It typically goes through the four stages discussed above and approximately 30% develop permanent hypothyroidism. Treatment is as outlined above. It is very likely (70%) to occur in subsequent pregnancies.
De Quervain’s thyroiditis (subacute granulomatous thyroiditis)
De Quervain’s presents with pain and tenderness of the thyroid. Patients usually also complain of pain on swallowing. Geographical and seasonal (summer and autumn) clustering of cases occurs. Many viruses including mumps, echovirus, EBV, influenza and adenovirus have been implicated. A markedly raised ESR and raised thyroglobulin level are seen. A normal ESR or a normal thyroglobulin level rules out the condition. It typically goes through the four stages discussed above and approximately 10% develop permanent hypothyroidism. Treatment is as outlined above. The pain usually responds to high-dose NSAIDs (ibuprofen up to 1800mg per day). If the pain is not controlled within four days, commence high-dose prednisone. Patients may need to be on prednisone for up to 4–6 weeks before weaning slowly off prednisone.
Acute suppurative thyroiditis
Acute suppurative thyroiditis is uncommon. It is usually caused by Staph aureus or Strep spp. It is associated with either immunosuppression or fistula of the pyriform sinus. It presents with a systemically unwell patient with fever and a tender, enlarged thyroid lobe. The overlying skin may be erythematous. The ESR and CRP are elevated. Treatment is with antibiotics. There should be a low threshold to request an ultrasound, which may reveal an abscess. Any abscess should be drained surgically. Subsequent elective hemithyroidectomy plus or minus excision of any associated fistula may be required. Pharyngoscopy may reveal the opening a fistula in the pyriform fossa (third and fourth arch congenital branchial cleft fistula).
Riedel’s thyroiditis
Riedel’s thyroiditis presents as a bony, hard thyroid mass. About one third of patients develop other areas of fibrosis, including sclerosing cholangitis, retroperitoneal fibrosis or orbital pseudotumour. Diagnosis is with a biopsy. Sometimes hemithyroidectomy is required to make the diagnosis. Treated as symptomatic or surgical depending on the severity of the symptoms and VOICES OF THE SECTOR communications@rnzcgp.org.nz Do you have a story you’d like to share? Make your voice heard Submit your article to the Editorial team: GP VOICE | NOVEMBER 2024 | PAGE 2 7 Submit your feedback the certainty of diagnosis. Excising the thyroid isthmus may be enough to relieve symptoms in some patients. Medical treatment with prednisone, mycophenolate or tamoxifen has been tried. Graves’ disease See the October issue of GP Voice.
Drug-induced thyroiditis
Several drugs may induce thyroiditis. Amiodarone and lithium are probably the best-known drugs to induce thyroiditis. Other drugs that can induce thyroiditis include immune checkpoint inhibitors and tyrosine kinase inhibitors. Radiotherapy and RAI may also induce thyroiditis.
Summary
Thyroiditis is best categorised by the presence or absence of pain. Pain from De Quervain’s is treated with high-dose NSAIDs or prednisone. Some patients with thyroiditis develop permanent hypothyroidism. Surgery is reserved for patients with a thyroid abscess, symptoms from an enlarged thyroid or as definitive treatment of Graves’ disease and some cases of drug-induced thyroiditis.
References:
1. Martinez Quintero B, Yazbeck C, Sweeney LB. Thyroiditis: Evaluation and Treatment. Am Fam Physician. 2021 Dec 1;104(6):609-617.
2. Lafontaine N, Learoyd D, Farrel S, Wong R. Suppurative thyroiditis: Systematic review and clinical guidance. Clin Endocrinol (Oxf). 2021 Aug;95(2):253-264.
3. Ragusa F, Fallahi P, Elia G, Gonnella D, Paparo SR, Giusti C, Churilov LP, Ferrari SM, Antonelli A. Hashimotos’ thyroiditis: Epidemiology, pathogenesis, clinic and therapy. Best Pract Res Clin Endocrinol Metab. 2019 Dec;33(6):101367