Subacute thyroiditis is mostly caused by viral infection and is characterized by fever, painful and enlarged thyroid gland with systemic inflammatory reaction. In mild cases, anti-inflammatory and analgesic treatment can be given to reduce the inflammatory response and relieve pain. Glucocorticoids can rapidly relieve pain, reduce thyrotoxic symptoms, and shorten the course of the disease.
Subacute thyroiditis
Subacute thyroiditis is an abbreviation for subacute thyroiditis, which is most common in adults between the ages of 30 and 50, with a higher incidence in women than in men. The disease is mostly caused by viral infection of the thyroid gland and is characterized by transient painful and destructive thyroid tissue damage with a systemic inflammatory response.
Clinical presentation.
Onset is often 1-3 weeks after viral infection, with varying forms of onset and degree of illness.
1. Prodromal symptoms of upper respiratory tract infection.
Muscle pain, fatigue, lethargy, sore throat, etc., body temperature increases to varying degrees, peaking in 3-4 days after onset. May be accompanied by swollen lymph nodes in the neck.
2. Characteristic pain in the thyroid area.
It occurs gradually or suddenly, with varying degrees. It often radiates to the ipsilateral ear, throat, jaw angle, chin, occiput, and chest and back. A small number of patients have hoarseness and difficulty swallowing.
3. Enlarged thyroid gland.
Diffuse or asymmetric mild or moderate enlargement, mostly with nodules, hard texture, obvious tenderness, no tremor or murmur. Goiter often involves one lobe first and then extends to the other lobe.
4. Clinical manifestations associated with changes in thyroid function.
(1) Thyrotoxic stage: about 50%-75% of patients have weight loss, fever, tachycardia, etc. at the beginning of the disease, which lasts about 3-8 weeks;
(2) Hypothyroidism stage: About 25% of patients enter the hypothyroidism stage before the synthesis of thyroid hormones is restored, with symptoms such as edema, fear of cold and constipation;
(3) Thyroid function recovery stage: Most patients recover normal function for a short time (weeks to months), and only a few become permanently hypothyroid. The whole course of the disease lasts about 6-12 months. Some cases have recurrent exacerbations that last from a few months to 2 years. About 2-4% relapse and very few recurrent episodes.
Laboratory tests.
1, erythrocyte sedimentation rate (ESR), increased early in the course of the disease, > 50 mm / h is favorable to support the disease, ESR does not increase can not be excluded from the disease.
2. The thyrotoxic phase presents a bidirectional separation of elevated serum T4 and T3 concentrations and reduced thyroid iodine uptake (often less than 2%). As the destruction of thyroid follicular epithelial cells worsens, transient hypothyroidism occurs, with lower T4 and T3 concentrations and higher thyrotropin (TSH) levels. When the inflammation subsides and the thyroid follicular epithelium is restored, thyroid hormone levels and thyroid iodine uptake rate gradually return to normal.
FNAC is not used as a routine test to diagnose this disease.
4. thyroid nuclear scan: no uptake or low uptake of the thyroid gland in the early stage is helpful for diagnosis.
Diagnosis.
The disease can be diagnosed based on acute onset, systemic symptoms such as fever and a painful, enlarged and hard thyroid gland, combined with a significant increase in ESR and a bidirectional separation of elevated serum thyroid hormone concentration and reduced iodine uptake by the thyroid gland.
Differential diagnosis.
1. Upper respiratory tract infection: the presence of fever, anterior neck pain, and sore throat is easily misdiagnosed as epiglottitis or pharyngitis and treated with antibiotics. Therefore, patients with fever with cervicopharyngeal pain should consider the possibility of subxiphoiditis and perform thyroid-related tests.
2. Hemorrhagic nodular goiter: sudden bleeding may be accompanied by thyroid pain and fluctuating sensation at the site of bleeding; however, there are no systemic symptoms and ESR is not elevated; thyroid ultrasonography is helpful for diagnosis.
3. Hashimoto’s thyroiditis: a few may have thyroid pain and tenderness, ESR may be mildly elevated during the active phase, and transient thyrotoxicosis and reduced iodine uptake may occur; however, there are no systemic symptoms, and serum TgAb and TPOAb titers are elevated.
4. Painless thyroiditis: This disease is a variant of Hashimoto’s thyroiditis, a type of autoimmune thyroiditis. There is goiter and the clinical presentation goes through 3 stages of thyrotoxicosis, hypothyroidism and recovery of thyroid function, similar to subacute thyroiditis. Differentiation point: this disease has no systemic symptoms, no thyroid pain, ESR is not increased, FNAC examination is feasible to differentiate if necessary, focal lymphocytic infiltration is seen in this disease.
5, hyperthyroidism (hyperthyroidism): iodine-induced hyperthyroidism or hyperthyroidism in which the rate of iodine uptake is suppressed by exogenous iodide, with elevated serum T4 and T3, but reduced 131I uptake, needs to be differentiated from subacute thyroiditis. The differentiation can be based on the duration of the disease, systemic symptoms, thyroid pain, T3/T4 ratio in hyperthyroidism and ESR.