Know your numbers: The Importance of Understanding Your Individual Thyroid Health Status


Going to the doctor’s office can be a troubling and confusing experience. Not because you don’t trust your doctor or feel comfortable with them, but because when it comes to test and diagnostics, the results are often times very confusing. Even with a basic doctor’s explanation, the numbers can be confounding. Educating yourself of what these numbers mean for your overall health, and your thyroid health can help you to decipher what your test results mean, and what your optimal results will be.

Blood Tests for Thyroid Health

If you’re monitoring your thyroid, you’ll come across several important thyroid tests conducted through a blood draw and accompanying test. These blood tests include TSH, T4, T3, free T4, and thyroid antibodies.

TSH TSH stands for thyroid-stimulating hormone, and the TSH test is used to check for problems with the thyroid gland. The TSH tests for an under-active thyroid (medically known as hypothyroidism), an overactive thyroid (hyperthyroidism), pinpoint the cause for an over or under-active thyroid, track overall function during thyroid condition treatments, and monitor for thyroid issues in newborns.

Results for a TSH test are generally available between two and three days after conducting the test. Lab values may vary, and most results come with a range form. However, these are the basic ranges. For adults, 0.4-4.2mcU/mL or mU/L. For children, 0.7-6.4mcU/mL or mU/L. For newborns, 1-39mcU/mL, or mU/L.

High values are associated with an under-active thyroid, too little thyroid medication for those on thyroid hormone for an under-active thyroid; or in very rare cases, a pituitary gland tumor. Low values are associated with an overactive thyroid, damage to the pituitary gland, or too much thyroid hormone medication. Pregnancy in the first trimester can also cause a temporary lower value for this test.

T4 Test T4 is a hormone that is created by the thyroid gland, and is used in evaluations of a woman’s fertility, in the determination of an auto-immune disorder, to determine overall thyroid function, or in the evaluation of a goiter. Newborns may also be tested on T4 levels, in conjunction with TSH levels in order to determine congenital hypothyroidism, which can lead to mental retardation, if it is not addressed.

When are T4 Tests Ordered? T4 tests are generally ordered in conjunction with a TSH test, or after an abnormal TSH result, in order to further hone in on the issue the patient is experiencing.

Test results for T4 tests are given on two separate levels. Free T4 and total T4. In levels of free and total T4 are found to be high, an overactive thyroid may be the case. If free and total T4 are low, under-active thyroid is assumed. In either case, additional testing will be done to confirm the diagnosis, and having a T3 and TSH tests will be necessary.

Total T4 is considered to be within range for an adult if levels are at 5.4-11.5mcg/dL, or 57-148nmol/L. Free T4 is considered within normal range for adults if they are within 0.7-2.0ng/dL, or 10-26pnmol/L.

What is Free T4? The term Free T4 is used to describe the type of T4 that is not bonded to a protein in the blood. Most of the T4 in your body will be bonded, so these levels can be clinically significant, and help a doctor to pinpoint thyroid irregularities and dysfunction.

T3 Test T3 is another hormone that is partially secreted by the thyroid gland, and partially created elsewhere in the body. T3 plays an important role in metabolism, which is one reason why an underactive or overactive thyroid causes changes in weight. T3 is also responsible for body temperature and heart rate. Also like T4, T3 exists in the body in free form, meaning that it is not attached to a protein. In a healthy, normally functioning body, free T3 is a less common form of T3.

Why is it Done? T3 tests are generally done in conjunction with other thyroid tests, such as T4 and TSH. The test is meant to assist in the diagnosis of thyroid dysfunction, particularly in the diagnosis of hyperthyroidism. As noted earlier, symptoms of this include a quickened heart rate, weight loss, and trembling.

The Results Because results can be translated differently based on your physician, or your lab, be sure to discuss all results with your doctor. Total adult T3 is considered in normal range when it is between 80-200ng/dL or 1.2-3.1nmol/L. Free T3 levels in adults are considered normal when they are within the 260-480pg/dL, or 4.0-7.4pmol/L range.

Thyroid Antibodies Test The last of the major thyroid function tests is a thyroid antibodies test known as the thyroid peroxidase (TPO) test. TPO is an enzyme that is found within the thyroid, and plays a role in the production of hormones that are secreted by the thyroid. A TPO test is ordered in order to determine the cause of a thyroid dysfunction diagnosis.

The Results If you tests show that TPO antibodies are present in the blood, the cause of your thyroid dysfunction is believed to be a result of an auto-immune disorder. Hashimoto’s disease and Graves’ disease are the most common of these conditions.

In some cases, thyroid antibodies will be present in the blood, but other thyroid tests will show appropriate thyroid hormone levels. In these cases, the TPO in the blood is believed to be a warning sign for a high risk of thyroid dysfunction development. If this is the case, your physician will likely ask for repeated tests over the course of the next couple of years to watch for the occurrence of thyroid issues.

This is just an overview of the specific thyroid tests that are important to uncover what is really at play for your overall health. Other tests I recommend include iodine, Vitamin D and Iron (to name a few). Keep your eyes open for coming blogs whe