Thyroid tests can help doctors to identify different abnormalities in the thyroid, like changes to size, the presence of tumors and changes to functioning. Some tests, like TSH, free T4 and T3, can also help to guide treatment by giving the doctor a parameter for thyroid medication dosing. Image tests, like a thyroid ultrasound, can help detect nodules that are impairing thyroid functioning.
More specific thyroid tests, like scintigraphy, a biopsy or antibody levels, can be ordered to determine certain diseases like thyroiditis or thyroid tumors. Read more about symptoms of thyroid problems that may occur if this gland is undergoing a disease pathology.
The thyroid tests that are most commonly ordered are:
1. Thyroid hormone levels
Thyroid hormone levels in the blood allow the doctor to evaluate functioning of this gland. They help to confirm the presence of hypo or hyperthyroidism.
Although normal levels may vary depending on the patient’s age, pregnancy and lab references, the normal levels are generally:
|TSH||0.3 to 4.0 mU/L|
|Total T3||80 to 180 ng/dl|
|Free T3||2.5 to 4 pg/ml|
|4.5 to 12.6 mg/dl|
|Free T4||0.9 to 1.8 ng/dl|
If changes to thyroid functioning have been identified, the doctor may order further testing, like ultrasound or antibody testing, to understand the underlying cause. Learn more about the TSH blood test specifically and what a high or low level can mean.
2. Antibody levels
Antibody levels are produced by the body with some auto-immune conditions, like Hashimoto’s thyroiditis or Graves disease. Some tests include:
- Thyroid peroxidase antibody (anti-TPO): Present in most cases of Hashimoto’s thyroiditis, an illness that triggers cellular injury and gradual decrease in thyroid function
- Antithyroglobulin antibody (anti-Tg): Present in many cases of Hashimoto’s thyroiditis, although it can appear with any thyroid abnormality and is not always a sign of disease
- Anti-TSH receptor antibodies (anti-TRAB): May be present in cases of hyperthyroidism, particularly with Graves disease
Thyroid antibodies should only be ordered by the doctor if thyroid hormone levels are abnormal, or if there is a suspician for thyroid disease and the doctor wants to investigate for an underlying cause.
3. Thyroid ultrasound
A thyroid ultrasound is ordered to evaluate the size of this gland and to detect changes like cysts, tumors or nodules. Although this test is unable to confirm cancer, it may be useful to detect characteristics of cancer. This test can prompt a thyroid nodule or cyst puncture to guide treatment.
4. Thyroid scintigraphy
A thyroid scintigraphy, or thyroid scan, is a test that uses a small amount of radiactive iodine and a special camera to generate a thyroid image. It helps to idnetify the level of activity in the gland.
This test is mainly ordered to investigate suspicious nodules, cancer or hyperthyroidism secondary to a nodule.
5. Thyroid biopsy
A thyroid biopsy or puncture and ordered to determine whether a nodule or cyst in the thyroid is benign or malignant. During this test, the doctor inserts a thin needle in the nodule and removes a small amount of tissue or fluid within the nodule for lab analysis.
A thyroid biopsy can hurt or cause discomfort because this test is not done under local anesthesia. The doctor may need to move the needle around during the exam to collect sufficient specimen in parts of the nodule or to aspirate most of the fluid. A thyroid biopsy is generally quick in takes about 10 minutes. Patients should keep the dressing over the area for several afters after.
6. Thyroid self-exam
A thyroid self-exam can be used to identify the presence of cysts or nodules in the thyroid. If lumps are detected in an early phase, it can prevent disease-related complications. This self-exam should be done my women over 35 or if patients have a family history of thyroid problems.
A thyroid self-exam can be done by:
- Standing in front of a mirror and determine where the thyroid is located. Is typically found directly under the Adam’s apple.
- Tilting the head back to better expose the area.
- Drinking a sip of water.
- Assessing thyroid movement and determining whether there is any asymmetry or protrusions.
If thyroid abnormalities are noted, you should see your family doctor or an endocrinologist for testing to confirm whether thyroid disease is present.
When thyroid tests are ordered
Thyroid tests are recommended for patients over 35, for patients with a family history of thyroid changes, pregnant women or women looking to become pregnant.
Testing may also be indicated following radiation treatment for neck or head cancer, or during treatment with medications like lithium, amiodarone or cytokines, which can interfere with thyroid functioning.