The thyroid is an endocrine gland that makes an important hormone responsible for multiple functions in the body. If the thyroid gland does not function properly, it can lead to various other issues, both short-term and long-term. For most health issues, doctors ask for a thyroid test. Do you know how to read these tests? Here is everything you need to know to decode that thyroid test result.
The thyroid is a butterfly-shaped gland in your endocrine system that is responsible for the production of multiple hormones in the body. Without these hormones, the bodily functions and balance will be disturbed. The thyroid gland makes the thyroid hormone, which influences various other hormones and functions in the body.
One of the most important roles this gland plays is controlling the metabolism. The metabolism rate is the speed at which the body processes the foods we eat, transforming them into energy for consumption. So, when this thyroid gland does not work properly, it can not only affect the hormone secretion but also affect the metabolism and the entire functioning of the body.
A thyroid test checks if the thyroid gland is functioning properly and producing all the necessary hormones at the right levels. When you face issues like fatigue, mood swings, sudden changes in weight or sluggishness, doctors will first check your thyroid levels.
Thyroid tests are predominantly blood tests that check the levels of hormones and antibodies in the body. If the blood test results are concerning or inconclusive, the doctor may ask for a thyroid imaging test to get a better look at the gland and the surrounding areas.
The thyroid test measures the levels of certain hormones and antibodies in the body. Too much or too little of these can cause an imbalance in the body, leading to other health issues. In some cases, an abnormal thyroid test result is the first indication of a serious health issue. Doctors will recommend further tests to confirm the diagnosis.
A thyroid test can help diagnose issues like –
● Hypothyroidism – The Thyroid gland is underactive, decreasing hormone production and slowing down the metabolism. This will cause excess weight gain and sluggishness.
● Hyperthyroidism – The Thyroid gland is overactive, producing excess hormones and speeds up metabolism. This will cause weight loss, increased heart rate and anxiety.
● Thyroiditis – It refers to a group of health conditions that are caused by the inflammation of the thyroid gland. While some impacts of thyroiditis are temporary and treatable, some are permanent.
● Graves’ disease – It is an autoimmune disease that impacts the thyroid gland and makes it overactive (producing more thyroid hormone).
● Hashimoto’s disease – A lifelong autoimmune disease that causes the thyroid gland to underwork (produce lesser than normal levels of thyroid hormone).
The components of the test result will vary according to its type. While the blood test will check the blood thoroughly for hormones and antibodies, the imaging tests will help get a closer look at the size, shape and functioning of the thyroid gland.
A thyroid blood test result will contain details regarding the following –
● TSH – TSH stands for Thyroid Stimulating Hormone. This is the first thyroid-related test any doctor would ask for. The pituitary gland in the brain makes the TSH, which in turn stimulates the thyroid gland to make T3 and T4 hormones.
● T3 – Measure the level of triiodothyronine in the blood.
● T4 – Measures the level of thyroxine in the blood.
● Thyroid Antibody – Provides information about the presence or absence of thyroid antibodies in the bloodstream.
● Thyroid Ultrasound – Through the use of sound waves, the ultrasound will check the size, shape and position of the thyroid gland. It is a non-invasive test that can also help detect lumps in the neck.
● Thyroid Scans – Through a CT scan, the healthcare professional will check the size and positioning of the thyroid gland. In the case of concerns, they will use a contrast material (injected or via capsule) to get a better picture of the entire system.
● Thyroid Uptake Tests – You will swallow a small amount of radioactive iodine a few hours before the test. With the help of a gamma probe, your healthcare provider will check the functioning of the thyroid gland. It is a non-invasive test and may be taken again after 24 hours for consistent readings.
Now that you know what all components your thyroid test will cover, do you know how to decode the test results? Do you know what those numbers on that result mean? Don’t worry, we are here to help you.
● High TSH – Now we know TSH is the hormone that stimulates the thyroid gland to produce two important hormones. When your TSH levels are high, it means your thyroid gland is underactive and is not producing enough of the T3 and T4 hormones. So, your pituitary gland is producing more of TSH in an attempt to stimulate the thyroid gland to work more.
● Low TSH – In this case, the pituitary gland is producing more than the required amount of TSH hormone because there is excess thyroid hormone in your body. Which means your thyroid gland is hyperactive/overactive. This will ideally lead to high T3 and T4 hormone levels.
Hyperthyroidism is not common and, in most cases, is caused by another health issue. Graves' disease and thyroid nodules are the common causes of hyperthyroidism. So, if your TSH levels are low, you may have other issues. So, your doctor will next order tests to check for the possible causes.
● High T3 and T4 – T3 and T4 are the hormones produced by the thyroid gland, and these hormones regulate body temperature, metabolism and energy. If these levels are higher than normal, it indicates the possibility of hyperthyroidism – an overactive thyroid.
● Low T3 and T4 – When T3 and T4 levels are lower than normal, it indicates hypothyroidism - an underactive thyroid gland not producing enough of these hormones. (primary hypothyroidism)
It could also be due to insufficient TSH produced by the pituitary gland, meaning there is a problem with the pituitary gland and not the thyroid gland (secondary hypothyroidism). Some chronic conditions can also affect the way the body converts the T4 hormones into the T3 hormone, leading to low T3 and T4. It could also be as simple as iodine deficiency, as it can impair the thyroid gland’s ability to secrete these hormones.
● Thyroid Antibody Positive – If the result shows higher than normal levels of thyroid antibodies in the blood, it can indicate an autoimmune thyroid disease like Hashimoto’s thyroiditis or Graves' disease.
The common types of thyroid antibodies found in the blood are - Thyroid peroxidase antibodies (TPOAb), Thyroglobulin antibodies (TgAb) and TSH receptor antibodies (TRAb).
● Free Vs. Total – The test will also check the levels of free T3 and T4 hormones in the blood. Some of these T3 and T4 hormones are protein-bound, and some are free and biologically active. Free T3 and T4 indicate the levels of these hormones that are free and biologically active. Total T3 and T4 measure both the free and the bound hormones.
● Thyroid Antibody Negative – The absence of thyroid antibodies in the body means the thyroid-related symptoms you are experiencing are not due to an autoimmune disease. You will need further tests to identify the source or reason for your thyroid issues.
In the case of thyroid-related issues, most tests will fall into one of these categories –
● Primary Hypothyroidism - TSH is high, but Free T4 is low.
● Hyperthyroidism - TSH is low, but free T4 is high.
● Subclinical Hypothyroidism - TSH is high, but free T4 is within normal range.
When you undergo a thyroid test and try to understand the test results, remember the following factors –
● The reference ranges will vary from lab to lab. Ensure you refer to the range mentioned by your lab only and discuss with your doctor if concerned, before drawing your own conclusions.
● Biotin can interfere with thyroid test results. If you are taking any biotin supplements or medications, ensure you inform your doctor about the same.
● The timing of the test, your stress levels, health issues, and pregnancy can influence TSH levels.
The thyroid hormone is important and influential in the body. A thyroid test can reveal important information and help doctors identify the health issue more precisely. Always discuss your thyroid test results only with a professionally qualified doctor. Never go by what the internet or other patients say.
T3 is Triiodothyronine, and T4 refers to Thyroxine. While both hormones are produced by the thyroid gland, T3 is more active of the two. The body produces more of the T4, which is then converted to T3 in the liver, kidneys and other organs to regulate metabolism, energy and growth.
TSH refers to Thyroid Stimulating Hormone, produced by the pituitary gland. This hormone stimulates the thyroid gland to secrete T3 and T4 hormones. If TSH is high, it indicates there is less than the required T3 and T4 in the body. If TSH is low, it indicates T3 and T4 secretion is high, which can indicate hyperthyroidism.
Yes, if you are suffering from Hashimoto’s disease or subclinical hypothyroidism, you can experience thyroid symptoms like fatigue, brain fog, etc, with normal TSH levels. Further testing is required to identify the root cause of the thyroid issue.
High T3 with normal TSH and T4 levels indicates T3 toxicosis. It is when the thyroid produces more of the T3 hormone than the T4 hormone. It could also be due to an iodine deficiency for a prolonged period of time.
