OVERVIEW

What is nodular goiter?

Nodular goiter, also known as adenomatous goiter, is the late-stage manifestation of simple goiter.

Simple goiter is an enlargement of the thyroid gland caused by iodine deficiency, intake of goitrogenic substances, genetic factors, or congenital defects. It typically does not involve thyroid dysfunction (hyperthyroidism or hypothyroidism).

Initially, the thyroid gland enlarges diffusely and uniformly, known as diffuse goiter. Over time, as the condition progresses, one or more nodules develop during the gradual hyperplasia and enlargement of the thyroid, resulting in nodular goiter.

Is nodular goiter common?

Nodular goiter is relatively common, affecting about 4 out of every 100 people.

Since nodular goiter is a late-stage manifestation of simple goiter with a prolonged course, it is more frequently observed in older adults.

SYMPTOMS

What are the manifestations of nodular goiter?

The main manifestation of nodular goiter is neck swelling. Enlarged thyroid tissue can be felt in the front of the neck, and one or several nodules may even be palpable, usually without pain.

If the thyroid enlargement is particularly significant, it may compress surrounding organs, leading to symptoms such as throat tightness, difficulty breathing, hoarseness, difficulty swallowing, swelling of the face and one upper limb, facial cyanosis, constriction of one pupil, sinking of one eyeball, or drooping of one eyelid.

What complications or concurrent diseases can nodular goiter cause?

• Intranodular hemorrhage: Sudden neck swelling accompanied by pain, with the enlarged mass potentially shrinking over several weeks.

• Hyperthyroidism: Symptoms may include fatigue, palpitations, increased appetite, weight loss, heat intolerance, excessive sweating, irritability, and insomnia.

• Thyroid adenoma: Usually a benign tumor.

• Thyroid cancer: A small number of nodular goiters may be associated with thyroid cancer, primarily differentiated thyroid cancer, especially papillary carcinoma.

CAUSES

What are the causes of nodular goiter?

The causes of nodular goiter include the following:

• Iodine deficiency: Mainly seen in iodine-deficient mountainous areas. Since China implemented the policy of iodized salt, iodine deficiency has become rare. Elderly patients are primarily affected by iodine deficiency-induced nodular goiter.

• Intake of goitrogenic substances: Such as excessive fluoride in drinking water, or drugs like thioamides, sulfonamides, and lithium salts, which may cause thyroid enlargement. Additionally, pregnant women taking antithyroid drugs, lithium salts, or amiodarone may lead to goiter in newborns.

• Excessive iodine: Besides iodine deficiency, excessive iodine can also cause thyroid enlargement. This is common in areas with high water iodine, high-iodine diets, intake of iodine-containing drugs, or excessive iodine supplements.

• Family heredity and congenital defects.

• Autoimmune abnormalities.

Is nodular goiter hereditary?

It may be hereditary.

Is nodular goiter contagious?

No.

DIAGNOSIS

What tests are needed for nodular goiter?

• Thyroid ultrasound: The ultrasound may reveal thyroid enlargement with one or multiple nodules, possibly accompanied by fibrosis, calcification, cysts, colloid retention nodules, or adenomatous hyperplastic nodules.

• Thyroid function and thyroid antibodies: Blood tests are required. TSH, T3, and T4 are usually normal, while thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) are negative or only mildly elevated. If nodular goiter is complicated by hyperthyroidism, TSH levels may decrease.

• Iodine uptake test: The iodine uptake rate in nodular goiter is normal or increased, without early peak uptake.

• Thyroid scintigraphy: The distribution of radionuclides in nodular goiter is uneven.

• Urinary iodine measurement: For adults, urinary iodine < 100 μg/L indicates iodine deficiency, while for pregnant women, < 150 μg/L suggests deficiency. However, single urinary iodine measurements are highly influenced by diet, and the testing method has limitations, making it difficult to accurately assess iodine nutritional status with a single test. Doctors may evaluate iodine deficiency by inquiring about diet and living environment.

• Thyroglobulin (Tg): Blood test required. Tg levels may be elevated.

• Thyroid fine-needle aspiration biopsy: A small amount of thyroid tissue is extracted with a needle for pathological examination to confirm nodular goiter.

Most people only need the first two tests for diagnosis. Doctors will decide whether additional tests are necessary based on individual circumstances.

What conditions should nodular goiter be differentiated from?

• Hashimoto's thyroiditis: Also presents with thyroid enlargement and possible nodules. However, thyroid antibodies (TgAb or TPOAb) are significantly elevated, and thyroid ultrasound shows diffusely heterogeneous echotexture with a grid-like pattern.

• Thyroid adenoma: Thyroid ultrasound reveals a well-defined boundary between the adenoma and surrounding tissue. Fine-needle aspiration biopsy can also help distinguish it from nodular goiter.

• Subacute thyroiditis: May also cause thyroid enlargement and nodules. However, subacute thyroiditis typically has an acute onset with significant neck pain and fever. Thyroid function tests often show abnormalities (hyperthyroidism or hypothyroidism), and ultrasound may reveal patchy hypoechoic areas with markedly reduced iodine uptake.

• Thyroid cancer: Thyroid cancer is a malignant thyroid nodule. Ultrasound can preliminarily differentiate thyroid cancer from nodular goiter, as the former often appears as a solid hypoechoic nodule with ill-defined margins, microcalcifications, or a taller-than-wide shape. Fine-needle aspiration biopsy can confirm whether it is cancerous or benign.

TREATMENT

Which department should I visit for nodular goiter?

Endocrinology.

Is it necessary to seek medical attention for nodular goiter?

Yes.

If you notice thyroid enlargement or nodules, you should seek medical attention promptly.

Many thyroid conditions, including hyperthyroidism and thyroid cancer, can present as thyroid enlargement or nodules and require early treatment. Hospital examinations can help identify the specific thyroid issue.

How is nodular goiter treated?

• Iodine supplementation: If iodine deficiency is confirmed as the cause, iodine supplements like potassium iodide or compound iodine solution may be prescribed. Thyroid function should be closely monitored to avoid triggering hyperthyroidism.

• Thyroid hormone therapy: Thyroid hormone medication may reduce thyroid size, but nodules rarely disappear, and recurrence is common after stopping treatment. Long-term use may also lead to osteoporosis or heart disease, so this method is now rarely used.

• Surgery: Considered if the goiter is large, causes compression of nearby organs, affects quality of life, is unresponsive to medication, shows signs of malignancy, or for cosmetic reasons. Recurrence is possible post-surgery.

• Radioactive ¹³¹I therapy: Suitable for nodular goiter with hyperthyroidism but contraindicated in pregnancy. This treatment may cause permanent hypothyroidism, requiring lifelong medication.

Each treatment has pros and cons, and there is no consensus on the best approach.

For most patients without iodine deficiency, hyperthyroidism, or significant compression symptoms, doctors often recommend observation (no treatment) with regular follow-ups.

Does nodular goiter require hospitalization?

Generally not, unless surgery is needed.

Is follow-up necessary for nodular goiter? How often?

Yes, to detect potential thyroid dysfunction or malignancy early.

If no complications arise, annual check-ups (thyroid function tests and ultrasound) are typical. Stable cases may extend intervals. Follow your doctor's advice.

Can nodular goiter be completely cured?

20% of female and 5% of male simple goiter cases may stabilize or improve spontaneously. However, once nodular goiter develops, regression is unlikely.

DIET & LIFESTYLE

What should patients with nodular goiter pay attention to in daily life?

• Avoid squeezing or hitting the thyroid nodule to prevent internal bleeding in the nodule.

• Follow the doctor's instructions for regular check-ups.

• Seek medical attention promptly if symptoms such as heat intolerance, excessive sweating, palpitations, hand tremors, increased appetite, weight loss, neck pain, sudden neck lumps, hoarseness, difficulty breathing, or difficulty swallowing occur.

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

• Consume iodized salt: Unless you have hyperthyroidism, live in a high-iodine water area, require radioactive ¹³¹I treatment, or have specific doctor's instructions, iodized salt should be used. Avoid storing iodized salt in damp, direct sunlight, or high-temperature environments.

• Eat seafood in moderation: Avoid excessive long-term consumption of seaweed, kelp, shrimp, and shellfish. Seafood is delicious, but don’t overindulge.

• If nodular goiter is complicated by hyperthyroidism, use non-iodized salt and avoid seafood.

Does nodular goiter affect fertility?

As long as there are no thyroid function abnormalities, it generally does not affect fertility.

Women planning to conceive should take the following steps:

• First, address any iodine deficiency or excess.

• Check thyroid function to determine if hyperthyroidism or hypothyroidism is present. If so, ensure thyroid function is well-controlled before pregnancy.

• Undergo a thyroid ultrasound to rule out thyroid adenoma or thyroid cancer.

• If radioactive ¹³¹I treatment has been performed, wait 6 months to 1 year before conceiving.

PREVENTION

What are the ways to prevent nodular goiter?

• Consume iodized salt and seafood in moderation.

• Pregnant and breastfeeding women should follow medical advice for additional iodine supplementation.