OVERVIEW

What is thyroiditis?

Thyroiditis is inflammation of the thyroid gland caused by various factors such as infection or autoimmune disorders. Destruction of thyroid follicles leads to the release of large amounts of thyroid hormones into the bloodstream, which may result in thyrotoxicosis, manifesting as heat intolerance, palpitations, and hand tremors. During thyroid repair, insufficient thyroid hormone secretion may also lead to hypothyroidism, presenting as cold intolerance, edema, and fatigue.

Patients with thyroiditis typically exhibit a pattern of hyperthyroidism followed by hypothyroidism, then recovery.

Different causes of thyroiditis lead to variations in disease presentation, treatment approaches, and recovery outcomes.

Common types of thyroiditis include subacute thyroiditis, Hashimoto's thyroiditis, and postpartum thyroiditis. Search for related diseases on the Dingxiang Doctor App for further details.

Is thyroiditis common?

It is very common, especially among women.

What are the types of thyroiditis?

Thyroiditis is a collective term for a group of diseases. Based on the speed of onset, it can be classified as:

• Acute: e.g., acute suppurative thyroiditis;
• Subacute: e.g., subacute thyroiditis;
• Chronic thyroiditis: e.g., Hashimoto's thyroiditis. Based on whether it is autoimmune-related, it can be classified as:
• Autoimmune thyroiditis: e.g., Hashimoto's thyroiditis, atrophic thyroiditis, painless thyroiditis, postpartum thyroiditis;
• Non-autoimmune thyroiditis: e.g., acute suppurative thyroiditis, subacute thyroiditis.

What is autoimmune thyroiditis?

Autoimmune thyroiditis is a subset of thyroiditis and a general term for a broad category of diseases. It is caused by genetic, environmental, and other factors leading to autoimmune disorders of the thyroid gland. The main feature is elevated thyroid antibody levels (including thyroid peroxidase antibody TPOAb and thyroglobulin antibody TGAb), which may result in permanent hypothyroidism.

Hashimoto's thyroiditis, atrophic thyroiditis, painless thyroiditis, and postpartum thyroiditis all belong to autoimmune thyroiditis.

SYMPTOMS

What are the manifestations of subacute thyroiditis?

Subacute thyroiditis, abbreviated as SAT, is the most common thyroiditis in clinical practice. It presents with prominent local thyroid symptoms, including thyroid enlargement, firm texture, and significant tenderness. "Firm, swollen, and painful" are its characteristic features.

In addition to local thyroid manifestations, there are symptoms related to thyroid destruction and the release of thyroid hormones into the bloodstream, leading to thyrotoxicosis. This thyrotoxicosis is often transient and occurs over a short period, distinguishing it from true hyperthyroidism.

What are the manifestations of Hashimoto's thyroiditis?

Hashimoto's thyroiditis is the most common type of autoimmune thyroiditis. Its main features include elevated thyroid antibodies, diffuse thyroid enlargement, and a firm texture.

The disease progresses slowly, and early stages may lack clinical symptoms, with hypothyroidism appearing in later stages. Most patients seek medical attention due to goiter or hypothyroidism.

Fine-needle aspiration cytology of the thyroid can aid in diagnosis, but since it is an invasive procedure, it is generally less commonly used.

What are the manifestations of atrophic thyroiditis?

Atrophic thyroiditis is similar to Hashimoto's thyroiditis, with the key difference being that Hashimoto's thyroiditis involves thyroid enlargement, while atrophic thyroiditis involves thyroid atrophy. Some consider atrophic thyroiditis to be the final stage of Hashimoto's thyroiditis.

What are the manifestations of painless thyroiditis?

Painless thyroiditis follows a disease progression similar to subacute thyroiditis, but without thyroid pain. However, thyroid antibody levels are elevated. A certain proportion of cases eventually develop permanent hypothyroidism.

What are the manifestations of postpartum thyroiditis?

Postpartum thyroiditis is an autoimmune thyroiditis that occurs after childbirth. It is generally believed that patients have latent autoimmune thyroiditis, with pregnancy acting as a trigger for disease progression. Its disease course resembles painless thyroiditis, except that it occurs within 1 year after pregnancy.

Additionally, pregnancy may also trigger postpartum Graves' disease, so when diagnosing this condition, TRAb testing should be performed for differentiation.

CAUSES

What are the causes of thyroiditis?

The causes vary depending on the type of thyroiditis:

• Infection: Refers to thyroiditis caused by pathogens such as bacteria, viruses, or fungi, such as acute suppurative thyroiditis or subacute thyroiditis;
• Autoimmune disorders: Autoimmune thyroiditis results from abnormal immune regulation and is associated with genetic, environmental factors, and specific physiological stages (e.g., pregnancy);
• Radiation: Radiation thyroiditis is caused by exposure to radioactive isotopes.

Is thyroiditis hereditary?

Autoimmune thyroiditis has a certain genetic predisposition, and individuals with affected family members are more likely to develop the condition. However, having a relative with the disease does not guarantee that one will develop it.

Who is more prone to thyroiditis?

Thyroiditis is more common in women, particularly adult women, with the highest incidence occurring between the ages of 30 and 50.

Is there a relationship between thyroiditis and thyroid nodules?

Thyroid ultrasound detects asymptomatic thyroid nodules at a high rate, approximately one-third. Although some forms of thyroiditis may present with nodular changes or residual inflammatory nodules, simple thyroid nodules are generally unrelated to thyroiditis.

If a simple thyroid nodule is found, regular follow-up examinations, radioactive isotope scans, or fine-needle aspiration cytology should be performed to determine the nature of the nodule.

DIAGNOSIS

What is the thyroid function like during thyroiditis?

Overall, the thyroid function in most thyroiditis cases changes at different stages.

• In the early stage, due to the destruction of thyroid follicles, excessive thyroid hormones are released into the bloodstream, manifesting as decreased thyroid-stimulating hormone (TSH), elevated thyroxine (T4), and elevated triiodothyronine (T3);
• Later, as the stored thyroid hormones are depleted, TSH increases while T4 and T3 decrease;
• Finally, through self-repair, thyroid function either returns to normal or progresses to permanent hypothyroidism (elevated TSH, decreased T3 and T4).

What is the difference between thyroiditis and hyperthyroidism?

In the early stage of thyroiditis, symptoms may resemble "hyperthyroidism," which is actually thyrotoxicosis and differs from the typical hyperthyroidism (i.e., Graves' disease). Generally, oral anti-hyperthyroidism medications are not required.

Methods such as local thyroid signs, thyroid ultrasound, iodine uptake tests, and radionuclide scans can help differentiate true hyperthyroidism from "hyperthyroidism" caused by thyroiditis.

TREATMENT

Which department should I visit for thyroiditis?

Endocrinology.

How is thyroiditis treated?

First, the specific type of thyroiditis must be diagnosed, as treatment methods and outcomes vary depending on the type.

Can thyroiditis be cured?

This depends on the specific type of thyroiditis.

• If it is subacute thyroiditis, which is self-limiting, it can usually be cured, and thyroid function often returns to normal. The likelihood of permanent hypothyroidism is low (5%–10%).
• If it is autoimmune thyroiditis, some cases may eventually develop into hypothyroidism, requiring lifelong thyroid hormone replacement therapy.

If thyroid function returns to normal in thyroiditis, will thyroid antibodies disappear?

In patients with autoimmune thyroiditis, thyroid function may return to normal, but thyroid antibodies may still persist. There are no effective medications or methods to reduce antibody levels.

When is antithyroid treatment needed for thyroiditis?

• In rare cases where it is difficult to distinguish between true hyperthyroidism and thyrotoxicosis caused by thyroiditis, antithyroid treatment may be administered if hyperthyroidism is significant.
• Even in cases of thyrotoxicosis caused by thyroiditis, if symptoms are particularly severe, short-term antithyroid medication may be used.
• A small number of Hashimoto's thyroiditis cases may develop true hyperthyroidism (i.e., "Hashitoxicosis"), which requires antithyroid treatment.

When is thyroid hormone replacement therapy needed for thyroiditis?

Thyroid hormone replacement therapy (i.e., L-T₄ replacement) is required during the hypothyroid phase of thyroiditis or if permanent hypothyroidism develops, to maintain normal serum thyroid hormone levels.

When is surgical treatment needed for thyroiditis?

• Surgery may be considered if thyroiditis causes thyroid enlargement that compresses the trachea and does not improve with medication.
• Surgery may also be an option if thyroiditis leads to thyroid enlargement accompanied by malignant nodules.

Is radioactive ¹³¹I therapy needed for thyroiditis?

Radioactive ¹³¹I therapy is a common treatment for hyperthyroidism, often used when oral antithyroid drugs are ineffective. Thyroiditis generally does not require radioactive ¹³¹I therapy.

DIET & LIFESTYLE

What dietary and lifestyle precautions should patients with thyroiditis take?

The general precautions for various types of thyroiditis are similar, mainly involving adequate rest and avoiding excessive consumption of high-iodine foods such as kelp, seaweed, algae, jellyfish, and dried shrimp.

Quitting smoking, limiting alcohol, maintaining a regular schedule, and other healthy habits are beneficial for disease recovery.

Can patients with thyroiditis conceive and have children?

Both male and female patients should carefully consider fertility issues if thyroid function is abnormal during the active phase of thyroiditis, as both hyperthyroidism and hypothyroidism may adversely affect pregnancy and the fetus.

However, if thyroiditis is in the recovery phase or if permanent hypothyroidism is well-controlled with replacement therapy and thyroid function is normal, having children is possible.

For female patients with normal thyroid function but persistently high thyroid antibody levels, closer monitoring of thyroid function and adequate iodine supplementation during pregnancy are recommended.

PREVENTION

How to Prevent Thyroiditis?

We can prevent thyroiditis through the following methods:

• Reduce stress and maintain a positive, optimistic attitude;

• Adjust dietary structure, maintain a balanced diet, and avoid iodine deficiency or excessive iodine intake;

• Ensure adequate sleep and rest;

• Avoid ionizing radiation to the neck;

• Quit smoking.