The Thyroid

The thyroid is a soft, butterfly-shaped gland located at the base of your neck and in front of your throat. It has 2 almost symmetrical structures which look like butterfly wings called lobes; these lobes sit on each side of your windpipe. The isthmus connects the 2 lobes.

Functionality and Thyroid Hormone Imbalance

The role of the thyroid gland is to produce, store and circulate thyroid hormones in the entire body.

Thyroid hormones regulate breathing, heart rate, blood pressure, metabolism, menstrual cycles and mood. As such, an imbalance in thyroid hormone levels can negatively affect our vital body functions and mood. Thyroid hormone levels can be checked using blood tests. Blood tests can tell if the thyroid is hyperactive (hyperthyroidism) or underactive (hypothyroidism). Overt hyperthyroidism may be treated with antithyroid medication, radioactive iodine or surgery whereas overt hypothyroidism is usually treated with thyroid hormone medications.

Thyroid Cancer

On the more serious end of the spectrum, recent reports have shown that there is an increase in the number of cases of thyroid cancer globally in the past 3 decades. This is due to multiple risk factors, 1 of which is radiation exposure. Radiation exposure can be from medical treatment, radiation fallout from nuclear reactor accidents and from nuclear weapons. For unclear reasons, thyroid cancer occurs about 3 times more often in women than in men and can occur at any age but peaks in the 40s or 50s. Interestingly, there is also risk of thyroid cancer in people who are overweight or obese. Swelling, lumps or enlarged lymph nodes found in the neck are common symptoms of thyroid cancer.

Thyroid cancer manifests first as a thyroid nodule before enlarging into a mass if not treated. A nodule is growth of abnormal tissue which can be felt as a lump. Most thyroid nodules however, are non-cancerous with approximately 5% being cancerous. The commonest type of cancer is papillary thyroid cancer followed by follicular thyroid cancer being the 2nd most common.

Ultrasound in Thyroid Imaging

Ultrasound is the gold standard in thyroid imaging. It is utilised to look for thyroid enlargement, inflammation, nodules and masses as well as enlarged lymph nodes in the neck, in which the latter may be from spread of thyroid cancer. A risk stratification system for grading thyroid nodules called TI-RADS (Thyroid Imaging, Reporting and Data System) is used to identify nodules that warrant biopsy (tissue diagnosis) or ultrasound follow-up. These nodules are assessed based on composition (e.g solid, cystic, solid-cystic), echogenicity (brightness), shape, margins and presence of echogenic foci (bright spots). Nodules above a certain size that appear suspicious, are biopsied to get a definitive diagnosis i.e cancer or not cancer.


1. Yamashita S et al. Lessons from Fukushima: Latest Findings of Thyroid Cancer after Fukushima Nuclear Power Plant Accident. Thyroid. 2018 Jan 1;28 (1):11-22.

2. Wiltshire JJ et al. Systematic review of trends in the incidence rates of thyroid cancer. Thyroid 2016;26:1541-52.

3. Tessler F, Middleton WD, Grant EG. Thyroid Imaging Reporting and data System (TI-RADS): A User’s Guide. Radiology: Volume 287: Number 1-April 2018. pp 29-36.

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