Multinodular Goiter
A multinodular goiter is an enlarged thyroid gland containing multiple nodules. It is one of the most common thyroid conditions worldwide and often develops gradually over many years. Many multinodular goiters are first noticed as fullness in the neck or are discovered incidentally on imaging performed for another reason. Most thyroid nodules are benign, but a small proportion are cancerous. Some multinodular goiters also produce excess thyroid hormone, a condition known as toxic multinodular goiter. Ultrasound, thyroid-function blood tests, and, in selected patients, fine-needle aspiration biopsy, thyroid scintigraphy, CT, or MRI are central to evaluation and management.
What is it?
The thyroid is a butterfly-shaped gland located at the front of the neck. It produces thyroid hormones that help regulate metabolism, heart rate, body temperature, energy use, and many other body functions.
A goiter is an enlargement of the thyroid gland. A multinodular goiter is an enlarged thyroid containing multiple distinct nodules.
Individual nodules can differ in size, composition, and function. Some are solid, some are fluid-filled or cystic, and others contain both solid and cystic components. Calcification, fibrosis, degeneration, and previous bleeding can also produce a varied appearance.
Some nodules function normally, while others produce thyroid hormone independently of pituitary TSH regulation.
Multinodular goiter commonly develops gradually over years. Repeated cycles of thyroid-cell growth and involution can result in an irregular gland containing nodules of different sizes.
Iodine deficiency remains an important global cause. Iodine is required for thyroid-hormone production, and chronically inadequate intake can stimulate thyroid enlargement and nodule formation.
In regions with adequate iodine intake, multinodular goiter may be associated with age, genetic susceptibility, family history, autoimmune thyroid disease, previous radiation exposure, and other hormonal or environmental influences.
Female sex and increasing age are recognized risk factors. Pregnancy can temporarily affect thyroid size and hormone requirements, although pregnancy alone does not necessarily cause a persistent multinodular goiter.
A nontoxic multinodular goiter is a multinodular thyroid enlargement without hyperthyroidism. Thyroid function may be normal, although some patients can also have hypothyroidism from an associated thyroid disorder.
Toxic multinodular goiter occurs when one or more nodules produce excessive thyroid hormone independently of normal TSH control. It is an important cause of hyperthyroidism, particularly in older adults.
Patients with toxic multinodular goiter may have palpitations, tremor, heat intolerance, sweating, anxiety, sleep disturbance, frequent bowel movements, muscle weakness, or unintended weight loss.
Older adults may have less obvious symptoms and may instead present with atrial fibrillation, worsening heart disease, heart failure, weakness, or unexplained weight loss.
Many patients with a nontoxic multinodular goiter have no symptoms. The condition may be found during a physical examination, ultrasound, carotid imaging, chest CT, MRI, or another study.
As the gland becomes larger, it may cause visible neck fullness or a sensation of pressure or tightness.
Possible compressive symptoms include difficulty swallowing, cough, shortness of breath, and positional breathing discomfort. Hoarseness or persistent voice change requires evaluation because it may result from several causes, including compression, vocal-cord dysfunction, inflammation, or, less commonly, invasive malignancy.
A substernal or retrosternal goiter extends below the thoracic inlet and behind the breastbone. It may narrow or displace the trachea, esophagus, or major blood vessels.
Symptoms and imaging findings do not always correlate perfectly. Some large goiters cause few symptoms, while a smaller goiter in a confined location may produce meaningful compression.
Most nodules within a multinodular goiter are benign. However, the presence of multiple nodules does not eliminate the possibility of thyroid cancer.
Each clinically relevant nodule is evaluated according to its own ultrasound characteristics and size. Evaluation should not automatically focus only on the largest nodule because a smaller nodule may have more suspicious features.
Features that warrant further assessment may include rapid or progressive enlargement, a firm or fixed mass, persistent hoarseness, suspicious cervical lymph nodes, previous neck irradiation, or a strong family history of thyroid cancer.
Rapid enlargement can also result from bleeding into a benign nodule or cyst and does not always indicate cancer.
Diagnosis begins with a clinical history and neck examination. The clinician assesses thyroid size, nodularity, tenderness, mobility, compressive symptoms, voice changes, and cervical lymph nodes.
TSH is generally the initial blood test used to evaluate thyroid function.
When TSH is abnormal, free T4 and sometimes free T3 are measured. Thyroid antibodies may be checked when Hashimoto thyroiditis, Graves disease, or another autoimmune thyroid disorder is suspected.
Thyroid ultrasound is the primary imaging examination for characterizing multinodular goiter.
Ultrasound measures the thyroid gland, documents clinically relevant nodules, evaluates their composition and echogenicity, and assesses features such as margins, shape, echogenic foci, and possible extension beyond the thyroid.
The cervical lymph nodes can also be evaluated for suspicious features.
Ultrasound risk-stratification systems combine nodule appearance and size to determine whether fine-needle aspiration or ultrasound follow-up is recommended.
Not every thyroid nodule requires biopsy. Small nodules with reassuring features often require no biopsy, while nodules with more suspicious features may qualify for biopsy at a smaller size.
Fine-needle aspiration uses a thin needle, usually under ultrasound guidance, to collect cells from a selected nodule.
Biopsy results may be benign, malignant, suspicious, indeterminate, or nondiagnostic. Management depends on the cytology category, ultrasound pattern, clinical history, and patient preferences.
A benign biopsy substantially lowers the likelihood of cancer but does not necessarily eliminate all follow-up. Repeat ultrasound or biopsy may be considered if the nodule develops suspicious changes or grows significantly.
When TSH is low or suppressed, thyroid scintigraphy can identify areas that are producing thyroid hormone autonomously.
A hyperfunctioning or “hot” nodule is rarely malignant and generally does not require biopsy solely for cancer evaluation. However, ultrasound remains useful because other nodules within the gland may still meet biopsy criteria.
Nodules that are not hyperfunctioning are evaluated according to their ultrasound appearance, size, and clinical context rather than their scintigraphic appearance alone.
Thyroid scintigraphy is not routinely required when TSH is normal or elevated.
CT or MRI may be used when a goiter extends behind the breastbone, causes suspected airway or esophageal compression, or cannot be completely evaluated with ultrasound.
Cross-sectional imaging can show the lower extent of the goiter, tracheal narrowing or displacement, vascular relationships, and other anatomy important for surgical planning.
Iodinated contrast is used cautiously in patients with untreated hyperthyroidism because the iodine load can occasionally worsen hormone excess in susceptible patients, particularly those with toxic multinodular goiter.
Iodinated contrast can also temporarily interfere with thyroid scintigraphy or radioactive iodine treatment. However, contrast-enhanced CT may still be appropriate when its diagnostic benefit is important, such as when detailed vascular or surgical anatomy must be assessed.
The risks and benefits should be considered individually rather than automatically withholding a necessary contrast-enhanced examination.
Important to Know
Management depends on thyroid function, ultrasound findings, biopsy results, goiter size, substernal extension, compressive symptoms, age, overall health, and patient preferences.
Care may involve primary care clinicians, endocrinologists, radiologists, pathologists, nuclear medicine physicians, and endocrine or head-and-neck surgeons.
A small or moderately enlarged nontoxic multinodular goiter without suspicious nodules or compressive symptoms can often be observed.
Follow-up may include clinical examination, thyroid-function testing, and ultrasound. The timing and duration of surveillance depend on the nodules’ ultrasound risk patterns, biopsy findings, growth, and the patient’s clinical circumstances.
Routine long-term TSH-suppressive treatment with levothyroxine is generally not recommended for benign multinodular goiter in iodine-sufficient populations. Its ability to shrink nodules is limited, and excessive treatment can increase the risks of atrial fibrillation and bone loss.
Levothyroxine remains appropriate when a patient has true hypothyroidism.
Iodine deficiency should be corrected when established, but excessive iodine supplementation should be avoided because a sudden iodine load can trigger hyperthyroidism in susceptible patients with autonomous thyroid nodules.
Patients should not begin high-dose iodine or kelp supplements without professional guidance.
Toxic multinodular goiter usually requires treatment because persistent hyperthyroidism can increase the risks of atrial fibrillation, heart failure, bone loss, and other complications.
Beta blockers may be used to reduce palpitations, tremor, and other adrenergic symptoms. They improve symptoms but do not stop thyroid-hormone production.
Methimazole is generally the preferred antithyroid medication outside the first trimester of pregnancy and certain special circumstances. Propylthiouracil may be preferred during the first trimester of pregnancy or in selected urgent situations.
Antithyroid medications control hormone production but usually do not provide a permanent cure for autonomous multinodular disease. Hyperthyroidism generally returns when the medication is stopped unless definitive treatment has been completed.
Long-term antithyroid medication may nevertheless be appropriate for selected patients who cannot undergo or do not want radioactive iodine or surgery.
Radioactive iodine and surgery are both definitive treatment options for toxic multinodular goiter.
Radioactive iodine is taken up by functioning thyroid tissue and gradually reduces hormone production and gland volume. Improvement takes place over weeks to months, and some patients require more than one treatment.
Radioactive iodine may be less suitable when the goiter is very large, causes substantial compression, extends significantly into the chest, contains a suspicious nodule, or requires rapid removal.
Radioactive iodine can cause hypothyroidism, but hypothyroidism is not inevitable after treatment for toxic multinodular goiter. Some patients maintain normal thyroid function, while others develop hypothyroidism immediately or years later. Continued thyroid-function testing is necessary.
Radioactive iodine must not be administered during pregnancy. Breastfeeding must be stopped according to nuclear medicine guidance before treatment and cannot simply be resumed immediately afterward.
Surgery may be preferred for a very large goiter, meaningful airway or swallowing symptoms, major substernal extension, suspicious or malignant nodules, coexisting hyperparathyroidism requiring surgery, or a need for rapid definitive treatment.
Surgery may also be chosen based on patient preference or when radioactive iodine is unlikely to provide adequate reduction.
For bilateral multinodular goiter requiring surgery, total or near-total thyroidectomy is commonly performed because it treats the entire gland and reduces the likelihood of recurrent goiter.
Total or near-total thyroidectomy causes permanent hypothyroidism, requiring lifelong levothyroxine replacement.
Potential surgical complications include bleeding, temporary or permanent changes in calcium levels from parathyroid injury, and injury to the recurrent laryngeal nerves. The likelihood of complications is lower when surgery is performed by an experienced high-volume thyroid surgeon.
For substernal goiters, most operations can be performed through an incision in the neck. A chest incision or partial sternotomy is required only in a minority of cases with extensive or unusual intrathoracic anatomy.
Individual suspicious nodules are managed according to ultrasound and biopsy findings rather than simply because they occur within a multinodular gland.
A nodule with benign cytology may be monitored. A malignant or strongly suspicious result usually leads to surgical evaluation.
Indeterminate cytology may be managed with repeat biopsy, molecular testing, diagnostic surgery, or observation, depending on the cytology category, ultrasound findings, clinical risk, and patient preferences.
Thermal ablation methods include radiofrequency, laser, or microwave ablation. These treatments can reduce the size of selected benign nodules and improve pressure or cosmetic symptoms.
Before ablation, benignity usually needs to be established with appropriate biopsy, and the nodule’s location must be evaluated carefully. Thermal ablation is not a replacement for surgery when cancer is suspected or when a large multinodular gland causes diffuse compression.
Pregnancy requires individualized management.
Ultrasound and fine-needle aspiration can generally be performed safely during pregnancy when clinically indicated.
Diagnostic thyroid scintigraphy and radioactive iodine treatment are contraindicated during pregnancy. Radioactive iodine treatment is also not performed while breastfeeding.
When hyperthyroidism requires treatment during pregnancy, the lowest effective dose of an appropriate antithyroid medication is used. Propylthiouracil is generally preferred during the first trimester, with consideration of switching to methimazole afterward because of the risk of liver toxicity with prolonged propylthiouracil use.
Thyroid surgery during pregnancy is reserved for selected situations and, when necessary, is generally safest during the second trimester.
Adequate iodine nutrition is important, particularly during pregnancy, but supplementation should follow professional guidance because excessive iodine can also disrupt thyroid function.
New or worsening breathing difficulty, stridor, rapidly progressive swallowing difficulty, or rapidly enlarging neck swelling requires urgent evaluation.
A sudden painful increase in the size of a nodule may result from internal bleeding. Although this is often self-limited, urgent assessment is needed when it affects breathing, swallowing, or circulation.
Severe hyperthyroidism accompanied by high fever, marked agitation, confusion, severe vomiting, rapid or irregular heartbeat, chest pain, or heart failure may represent thyroid storm and requires emergency treatment.
Persistent hoarseness, a fixed neck mass, suspicious lymph nodes, or progressive unexplained enlargement requires prompt evaluation for possible malignancy or structural compression.