OVERVIEW

What is endemic goiter?

Iodine is the raw material for thyroid hormone synthesis.

Endemic goiter is an enlargement of the thyroid gland caused by insufficient or excessive iodine intake due to iodine deficiency or excess in the external environment, which may or may not be accompanied by thyroid dysfunction.

Its occurrence is related to the iodine content in the environment, and its distribution has a "localized" characteristic (i.e., particularly high incidence in certain areas), hence the name endemic goiter.

What are the types of endemic goiter?

It is generally divided into two types: low-iodine goiter caused by iodine deficiency and high-iodine goiter caused by excessive iodine intake.

SYMPTOMS

What are the common manifestations of endemic goiter?

The main manifestation is thyroid enlargement, and nodules may be palpable in some cases. As the thyroid grows, compression symptoms may occur:

• If it extends retrosternally and compresses the trachea, difficulty breathing may occur;

• Compression of the esophagus may lead to difficulty swallowing;

• Compression of the recurrent laryngeal nerve may cause hoarseness;

• Compression of the superior vena cava may cause unilateral facial, head, or upper limb edema.

Iodine-deficient goiter may also present with hyperthyroidism symptoms such as palpitations, hand tremors, excessive sweating, weight loss, and increased hunger. Some patients may exhibit hypothyroidism symptoms like cold intolerance, fatigue, lethargy, constipation, edema, and hair loss. If contracted during pregnancy, it may lead to intellectual disability, stunted growth, deaf-mutism, and hypothyroidism in the baby.

Excessive iodine intake may increase the risk of hypothyroidism, with symptoms similar to those mentioned above.

Can endemic goiter cause serious consequences?

If pregnant women or children suffer from iodine-deficient goiter, it can severely affect the child's intellectual and physical development.

Does iodine-deficient goiter always negatively impact a child's intelligence?

Iodine deficiency during pregnancy can lead to irreversible intellectual disability in the baby after birth.

If iodine-deficient goiter develops after birth in children, early treatment can significantly help improve intellectual outcomes.

CAUSES

What causes endemic goiter?

It includes two causes: insufficient iodine intake and excessive iodine intake.

Which groups are prone to endemic goiter?

Remote, economically underdeveloped mountainous areas often suffer from iodine deficiency, and residents there are prone to iodine-deficient endemic goiter.

In contrast, petroleum-producing regions, low-lying inland areas, and coastal regions are high-iodine areas, where residents often have excessive iodine intake and are prone to iodine-excess endemic goiter.

DIAGNOSIS

What tests are needed to diagnose endemic goiter?

Thyroid function, thyroid autoantibodies, thyroid ultrasound, urinary iodine.

Why do patients with endemic goiter need these tests? What is the purpose of these tests?

• Thyroid function: Used to assess whether there is thyroid dysfunction and its severity.

• Thyroid autoantibodies: Used to help diagnose whether autoimmune thyroiditis is present.

• Thyroid ultrasound: Used to evaluate the position, size, shape, presence of nodules, and blood flow of the thyroid.

• Urinary iodine: Used to assess the body's iodine nutritional status, including iodine deficiency, sufficiency, excess, or overload.

What precautions should patients with endemic goiter take when undergoing urinary iodine testing?

For urinary iodine testing, a random urine sample can be used, meaning urine can be collected at any time for testing.

If a 24-hour urine sample is collected for testing, urine collection should begin after the first morning void and continue until the first morning void at the same time the next day.

Which diseases can endemic goiter be easily confused with?

This condition can be easily confused with Hashimoto's thyroiditis, Graves' disease, central hypothyroidism, and other diseases. Doctors can differentiate them based on different clinical manifestations and related tests.

TREATMENT

Which department should I visit for endemic goiter?

Endocrinology or general internal medicine.

How is endemic goiter treated?

• Low-iodine goiter can be treated with iodine supplements, such as potassium iodide.

• High-iodine goiter requires iodine restriction, including the use of non-iodized salt. In areas with high iodine levels in water, measures to reduce iodine in the water supply may be necessary.

• If accompanied by hyperthyroidism, antithyroid drugs such as methimazole and propylthiouracil may be used. If accompanied by hypothyroidism, levothyroxine treatment is recommended.

• Surgical removal of the thyroid may be required if the goiter causes compressive symptoms such as difficulty breathing or swallowing.

Can patients with endemic goiter experience adverse reactions during iodine supplementation therapy?

Yes.

After iodine supplementation, patients with previously normal thyroid function may develop hyperthyroidism or hypothyroidism, but these can be corrected with symptomatic treatment. The benefits of iodine supplementation outweigh the risks.

Is follow-up necessary after treatment for endemic goiter? How should it be done?

Yes.

Patients with thyroid dysfunction should have their thyroid function checked at least once a month after starting medication, with less frequent monitoring once levels stabilize. Those taking antithyroid drugs should also regularly monitor liver function and blood counts.

Thyroid ultrasound should be repeated every 3–6 months.

Urinary iodine levels should also be checked regularly, such as every 15 days to 1 month.

Can endemic goiter be cured?

Some patients can be cured. In severe cases with a long disease course, the enlarged thyroid may not fully recover, requiring long-term medication (e.g., levothyroxine).

DIET & LIFESTYLE

What should patients with endemic goiter pay attention to in their diet?

• Patients with low-iodine goiter should appropriately increase their intake of iodine-rich foods under the guidance of a doctor, such as seaweed, kelp, shellfish, etc.

• Patients with high-iodine goiter should avoid iodine-rich foods and opt for non-iodized salt.

Can patients with endemic goiter have normal fertility?

After treatment, if thyroid function is controlled within the normal range, normal fertility is possible.

Is endemic goiter hereditary?

No.

PREVENTION

Can endemic goiter be prevented? How to prevent it?

Yes.

The general non-pregnant population can prevent iodine-deficient goiter by consuming iodized salt.

Women who are planning pregnancy, already pregnant, or breastfeeding need an additional 150 micrograms (µg) of iodine daily, on top of their normal diet. Potassium iodide is the preferred form of supplementation (or a multivitamin containing an equivalent dose). Those planning pregnancy should start supplementation 3 months in advance. Regular follow-ups are also necessary to avoid excessive iodine intake.

People in high-iodine areas should limit their intake of iodine-rich foods and medications to prevent iodine-excess goiter.