OVERVIEW

What is autoimmune thyroiditis?

Autoimmune thyroiditis (AIT) is a polygenic, multifactorial, complex disease syndrome characterized by the presence of thyroid-specific autoantibodies in the patient's serum (the immune system attacks the thyroid gland) and infiltration of lymphocytes in the thyroid. AIT primarily involves inflammatory destruction of the thyroid, with severe cases leading to hypothyroidism.

Is autoimmune thyroiditis common?

Internationally reported prevalence ranges from 1% to 2%. The incidence is 0.8 per 1,000 in males and 3.5 per 1,000 in females. The incidence in women is 3–4 times higher than in men, with the peak occurrence between ages 30–50. Chinese researchers report a prevalence of 1.6% and an incidence of 6.9 per 1,000.

What are the subtypes of autoimmune thyroiditis?

Autoimmune thyroiditis (AIT) is a polygenic, multifactorial, complex disease syndrome that mainly includes Graves' disease, chronic lymphocytic thyroiditis (Hashimoto's thyroiditis), autoimmune atrophic thyroiditis, postpartum thyroiditis, painless thyroiditis, and thyroid-associated ophthalmopathy.

SYMPTOMS

What are the common manifestations of autoimmune thyroiditis?

At different stages of the disease, it can manifest as normal thyroid function, hyperthyroidism, or hypothyroidism. In the late stages of the disease, there is a tendency to develop hypothyroidism, presenting symptoms such as fatigue, cold intolerance, constipation, weight gain, and non-pitting edema. Most cases are initially diagnosed due to goiter or hypothyroidism symptoms.

What serious consequences can autoimmune thyroiditis cause?

It may lead to permanent hypothyroidism in patients, which is related to the destruction of thyroid follicles.

CAUSES

What are the common causes of autoimmune thyroiditis?

• Genetic factors: Thyroid autoimmunity is familial. It has been reported that up to 50% of first-degree relatives of patients with some form of autoimmune thyroiditis have thyroid antibodies in their serum.

• Environmental factors: Such as excessive iodine intake, drug infections, stress, smoking, environmental pollution, etc.

• Endogenous factors: Such as puberty development, pregnancy, childbirth, menopause, aging, psychological and mental abnormalities, and being female.

Which groups are prone to autoimmune thyroiditis? Who should be vigilant?

People with radiation exposure, excessive iodine intake, or a family history of thyroid disease should be vigilant about autoimmune thyroiditis.

DIAGNOSIS

What tests are needed to diagnose autoimmune thyroiditis?

• Thyroid function (hormone levels);

• Thyroid autoantibodies: The gold standard for AIT diagnosis.

  • TgAb is a serum marker of AIT, but its positivity rate in Hashimoto's thyroiditis (HT) is not high, only 60%. TgAb levels correlate with the degree of lymphocyte infiltration in thyroid tissue, but it does not damage the thyroid. This antibody may interfere with the measurement of serum TgAb.

  • TPOAb is the best serum marker for AIT and the gold standard, with a positivity rate as high as 95% in HT. TPOAb levels correlate with the degree of lymphocyte infiltration in thyroid tissue. There is ongoing debate about whether TPOAb damages thyroid tissue, with some studies suggesting the damage primarily comes from B cells rather than the antibody itself.

Which diseases are easily confused with autoimmune thyroiditis?

Subacute thyroiditis, infectious thyroiditis, thyroid cancer, etc. Specific differential diagnosis should be performed by a specialist.

TREATMENT

Which department should I visit for autoimmune thyroiditis?

Endocrinology, Rheumatology, Immunology, Head and Neck Surgery, Thyroid and Breast Surgery.

Do all patients with autoimmune thyroiditis need treatment?

Clinical treatment mainly targets hypothyroidism and compressive symptoms caused by goiter. If there is no hypothyroidism or significant compressive symptoms, treatment is generally unnecessary.

How is autoimmune thyroiditis treated?

• For clinical or subclinical hypothyroidism, L-T4 replacement therapy is primarily administered.

• In cases of rapid thyroid enlargement accompanied by local pain or compressive symptoms, glucocorticoid therapy (prednisone 30 mg/d, divided into 3 oral doses, tapered after symptom relief) may be given.

• For significant compressive symptoms unresponsive to medication, surgical intervention may be considered, though the risk of postoperative hypothyroidism increases.

DIET & LIFESTYLE

What should patients with autoimmune thyroiditis pay attention to in daily life?

• If medication is required, it is recommended to take it consistently and not stop on your own. Follow medical advice and have regular check-ups.
• Quit smoking.
• Some medications contain iodine, such as amiodarone, which may worsen autoimmune thyroiditis. When seeking treatment for other conditions, inform your doctor about your autoimmune thyroiditis in advance.

What should patients with autoimmune thyroiditis pay attention to in their diet?

Limiting iodine intake to a safe range (urinary iodine 100–200 μg/L) may help slow the progression of thyroid autoimmune damage. Therefore, seafood can be consumed in moderation, but high-iodine foods like seaweed and kelp should not be consumed excessively or over long periods.

PREVENTION

Can Autoimmune Thyroiditis Be Prevented?

Due to its multifactorial causes, prevention is challenging. If a family member has autoimmune thyroiditis, the individual may have a higher risk and should avoid potential triggers such as excessive iodine intake, significant neck radiation exposure, smoking, and emotional stress. If hypothyroidism symptoms appear, seek medical attention promptly.