Enlarged thyroid (goitre) seen by chance on a scan

What the report means

Types of goitre. A goitre can be one smooth swelling of the whole gland (diffuse), or it can contain one or many lumps (nodular or multinodular). It can look quite different from one CT scan to another. (Bin Saeedan 2016)
Multinodular goitre. In a multinodular goitre, one or more nodules make the gland larger. Early on, the gland may not yet be enlarged, and the cause is not well understood. (ATA patient page)
Thyroid function. A goitre does not mean the thyroid is working badly. It can occur when the gland makes too much hormone, too little, or the right amount. (ATA patient page)
Other report words. A CT report may describe a goitre that reaches down behind the breastbone ("retrosternal extension") and whether it pushes on or narrows the windpipe or food pipe. An ultrasound shows nodules inside a goitre better than a CT. (Bin Saeedan 2016)

How common it is

Middle-aged adults. A Lithuanian study scanned 317 adults aged 48 to 49 with normal thyroid function. It found a goitre in 12.3%, with similar rates in men and women, and thyroid nodules in 31.2%, more often in women. People with a goitre had nodules more often than those without (59% vs 27%). (Dauksiene 2017)
Other groups. The same authors quote a figure of about 15.8% in the general population, and another study in which women were 2 to 10 times more likely than men to have a goitre. They note that how much iodine people get in their area is the main outside factor. (Dauksiene 2017)
Common causes. The NHS lists an overactive or underactive thyroid, harmless nodules, hormone changes during puberty, pregnancy or the menopause, an inflamed thyroid, immune conditions such as Graves' disease, low iodine (rare in the UK) and, rarely, thyroid cancer. (NHS) In the US, Hashimoto's thyroiditis is a more common cause than low iodine. (ATA patient page)

Which checks guidance lists

Blood tests first. The American Thyroid Association says the first step is usually thyroid function tests, to see whether the thyroid is underactive or overactive, and later tests depend on those results. (ATA patient page) See thyroid test results for what the numbers mean.
Other usual tests. The NHS lists blood tests, an ultrasound scan and sometimes a small needle sample from the thyroid to find the cause. (NHS)
When an ultrasound is advised. NICE advises an ultrasound of an enlarged thyroid with normal function if cancer is suspected, and says to consider one for a finding seen by chance on another scan if clinical factors suggest cancer is possible. (NICE NG145)
A nodule in the report. If the report names a single nodule, the size and look rules are on the thyroid nodule found by chance page.

Signs that need help

Symptoms the NHS lists. A cough that does not go away, a hoarse voice or voice changes, a feeling that something is stuck in your throat, a wheezing noise when you breathe, or trouble swallowing or breathing. (NHS)
Red flags NICE lists. Shortness of breath, nodules growing quickly, a hoarse voice and trouble swallowing. (NICE NG145)
See a GP. The NHS advises seeing a GP if you think you have a goitre. (NHS)
Worry is real. See after an abnormal screening result.

The NHS says to call 999 or go to A&E if you are finding it hard to breathe or have a wheezing noise when you breathe. (NHS)

How it ties to your age-based checks

A goitre found by chance is a good moment to make sure your routine checks are up to date:

Thyroid cancer screening in people without symptoms has its own page: thyroid cancer screening.

Who it applies to

Adults told that a CT, MRI or ultrasound done for another reason shows an enlarged or multinodular thyroid. Children and young people, pregnancy and people already being treated for a thyroid condition are outside this page.

Routine age-based screening

A finding on a scan does not replace the routine screenings for your age. See screenings by age and gender.

Where they differ:

Follow-up. The American Thyroid Association patient page says regular yearly monitoring is important once a goitre is found (ATA patient page), while NICE repeats an ultrasound and TSH test when cancer or pressure on the neck is suspected, and considers it when symptoms get worse or new ones such as hoarseness or shortness of breath appear. (NICE NG145)
Ultrasound. NICE ties an ultrasound to a suspicion of cancer (NICE NG145), while the NHS lists it among the usual tests to find the cause. (NHS)
Men and women. Another study, quoted by those authors, found goitre 2 to 10 times more often in women, while the Lithuanian study found similar rates in men and women. (Dauksiene 2017)
How common. Figures depend on the size cutoff used, the scan and how much iodine people get in the area studied. (Dauksiene 2017)

Your doctor decides what your result means for you.

Questions people ask

Is a goitre serious?

Usually not. The NHS says goitres are not usually serious but should be checked by a GP, and NICE says goitre and thyroid nodules are common and usually not cancerous. (NHS) (NICE NG145)

Does a goitre mean my thyroid is not working properly?

Not necessarily. The American Thyroid Association says a goitre can occur when the thyroid makes too much hormone, too little, or the right amount. (ATA patient page)

How common is a goitre?

Common. In a Lithuanian study of 317 adults aged 48 to 49 with normal thyroid function, an ultrasound found a goitre in 12.3%, with similar rates in men and women. (Dauksiene 2017)

Which tests might follow?

The American Thyroid Association says thyroid function blood tests usually come first. The NHS lists blood tests, an ultrasound scan and sometimes a needle sample. NICE advises an ultrasound when cancer is suspected. Your doctor decides. (ATA patient page) (NHS) (NICE NG145)

Do I need repeat scans?

Sources differ. The American Thyroid Association patient page says regular yearly monitoring is important, while NICE repeats an ultrasound and TSH test when cancer or pressure on the neck is suspected or symptoms get worse. Your doctor decides. (ATA patient page) (NICE NG145)