Thyroid Hormone Level Tests
There are four main thyroid hormones that have been identified: T1, T2, T3 and T4.
T4 and T3 are the two main thyroid hormones. T4 is known as prohormone and is 300 percent less biologically active than T3. T3 is the main biologically active thyroid hormone and gives us beautiful hair, replenishes our energy, and runs our metabolism.
You may have put together that most of the commonly prescribed thyroid medications like Synthroid and levothyroxine, only contain T4 , and thus they need to be converted to the active T3 form in the body.
On paper, the T4 to T3 conversion happens just fine, but in the real world, in real human bodies, we may not always convert T4 to T3.
We can reveal our T4 to T3 ratios and measure the hormone that is available to do its job in the body, by testing our free T4 and free T3 levels.
Free T3 and Free T4 tests measure the levels of active thyroid hormone circulating in the body.
Some clinicians may only test for T4, but T3 is also important to test, as some individuals may not be converting T4 to the active T3 properly. Thus, people may have a normal T4, but a low T3 level.
How Do You Know If You Are Converting Correctly?
Take a look at your free T3 and free T4 levels. Both should be in the optimal range. If the T4 is optimal, but the T3 is out of the optimal range, you know that your body is not making enough T3 hormone from the T4.
Optimal T4 reference range: 15-23 pmol/L
Optimal T3 reference range: 5-7 pmol/L
Thyroid Disorders And Symptoms
Underactive thyroid
If you dont produce enough thyroid hormones your bodily processes start to slow down. Signs of an underactive thyroid include:
- tiredness
Autoimmune thyroid diseases An autoimmune disease is when your immune system mistakenly attacks your body in this case, thyroid antibodies attack your thyroid. This can lead to a thyroid disorder. Types of autoimmune thyroid diseases include Graves disease or Hashimotos disease .
What Questions Should I Ask My Doctor
If you have thyroid cancer, you may want to ask your healthcare provider:
- Why did I get thyroid cancer?
- What type of thyroid cancer do I have?
- Has the cancer spread outside of the thyroid gland?
- What is the best treatment for this type of thyroid cancer?
- What are the treatment risks and side effects?
- Will I need thyroid replacement hormone therapy?
- Is my family at risk for developing this type of thyroid cancer? If so, should we get genetic tests?
- Can I get thyroid cancer again?
- Am I at risk for other types of cancer?
- What type of follow-up care do I need after treatment?
- Should I look out for signs of complications?
A note from Cleveland Clinic
Receiving a cancer diagnosis is unsettling, regardless of the type. Fortunately, most thyroid cancers respond extremely well to treatment. Your healthcare provider can discuss the best treatment option for the type of thyroid cancer you have. After treatment, you may need to take synthetic thyroid hormones for life. These hormones support vital body functions. They usually dont cause any significant side effects, but youll have regular checkups to monitor your health.
Last reviewed by a Cleveland Clinic medical professional on 08/13/2020.
References
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What Are Thyroid Nodules
A thyroid nodule is an unusual growth of thyroid cells in the thyroid gland.
The thyroid is part of the endocrine system, which is made up of glands that secrete various hormones into the bloodstream. The thyroid is a butterfly-shaped organ that is located on the front of the neck, just under the Adam’s apple . The thyroid gland, which is made up of the right and left lobes connected to the isthmus , produces and releases thyroid hormones. Thyroid hormones control functions such as body temperature, digestion and heart functions.
What Are Normal Thyroid Hormone Levels
The thyroid itself is regulated by another gland that is located in the brain, called the pituitary. In turn, the pituitary is regulated in part by the thyroid and by another gland called the hypothalamus.
The hypothalamus releases a hormone called thyrotropin releasing hormone , which sends a signal to the pituitary to release thyroid stimulating hormone . In turn, TSH sends a signal to the thyroid to release thyroid hormones. If a disruption occurs at any of these levels, a defect in thyroid hormone production may result in a deficiency of thyroid hormone .
Hypothalamus – TRH
Thyroid – T4 and T3
The rate of thyroid hormone production is controlled by the pituitary gland. If there is an insufficient amount of thyroid hormone circulating in the body to allow for normal functioning, the release of TSH is increased by the pituitary gland in an attempt to stimulate more thyroid hormone production. In contrast, when there is an excessive amount of circulating thyroid hormone, TSH levels fall as the pituitary attempts to decrease the production of thyroid hormone.
- In persons with hypothyroidism , there is a continuously decreased level of circulating thyroid hormones.
- In persons with hyperthyroidism , there is a continuously elevated level of circulating thyroid hormones.
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Changes In Menstrual Cycle Or Sexual Performance
Hormonal changes are closely linked to sexual function. If you find that your period is becoming irregular, heavier, or more painful than before, or if you are experiencing stronger emotional symptoms tied to PMS, your thyroid might be the cause.
You might also experience difficulty with sexual performance or enjoyment. If you are having difficulty with libido or achieving orgasm or if you cannot maintain an erection, you could also be struggling with a thyroid-related symptom.
While these are uncomfortable issues to talk about, they should absolutely be addressed with us to rule out not only thyroid trouble but also anything else that might quietly be causing these issues.
How Is Goiter Diagnosed
Several tests can be used to diagnose and evaluate goiter, including the following:
- Physical exam: Your doctor may be able to tell if the thyroid gland has grown by feeling the neck area for nodules and signs of tenderness.
- Hormone test: This blood test measures thyroid hormone levels, which tell if the thyroid is working properly.
- Antibody test: This blood test looks for certain antibodies that are produced in some forms of goiter. An antibody is a protein made by white blood cells. Antibodies help defend against invaders that cause disease or infection in the body.
- Ultrasound of the thyroid: Ultrasound is a procedure that sends high-frequency sound waves through body tissues. The echoes are recorded and transformed into video or photos. Ultrasound of the thyroid reveals the gland’s size and finds nodules.
- Thyroid scan: This imaging test provides information on the size and function of the gland. In this test, a small amount of radioactive material is injected into a vein to produce an image of the thyroid on a computer screen. This test is not ordered very often, since it is only useful in certain circumstances.
- CT scan or MRI of the thyroid: If the goiter is very large or spreads into the chest, a CT scan or MRI is used to measure the size and spread of the goiter.
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Who Might Have Thyroid Cancer
Women are three times more likely than men to get thyroid cancer. The disease is commonly diagnosed in women in their 40s and 50s, and men in their 60s and 70s. Even children can develop the disease. Risk factors include:
- Exposure to radioactive fallout from nuclear weapons or a power plant accident.
Look For Enlargements As You Swallow
As you swallow, look for any enlargements, lumps, protrusions, or anything that is off center. It is a good idea to repeat the process again, swallowing another mouthful of water, and observing the structures in your neck a few times.
Thyroid nodules are bumps that usually appear round. You may feel a thyroid nodule rolling beneath your fingertips or see it move with your thyroid gland when you swallow. A goiter may be seen on one side of the thyroid, and occasionally on both.
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Whats Included In A Full Thyroid Panel
A full thyroid panel usually checks thyroid-stimulating hormone , triiodothyronine , and thyroxine levels. In some cases, a blood test for thyroid function will also check your bloodâs level of TPO antibodies. If you have abnormal thyroid hormone levels, high levels of TPO antibodies can point to an autoimmune thyroid disease as a possible reason for those abnormal levels.
Is There A Higher Risk Of Developing Thyroid Disease If I Have Diabetes
If you have diabetes, youre at a higher risk of developing a thyroid disease than people without diabetes. Type 1 diabetes is an autoimmune disorder. If you already have one autoimmune disorder, you are more likely to develop another one.
For people with type 2 diabetes, the risk is lower, but still there. If you have type 2 diabetes, youre more likely to develop a thyroid disease later in life.
Regular testing is recommended to check for thyroid issues. Those with type 1 diabetes may be tested more often immediately after diagnosis and then every year or so than people with type 2 diabetes. There isnt a regular schedule for testing if you have type 2 diabetes, however your healthcare provider may suggest a schedule for testing over time.
If you have diabetes and get a positive thyroid test, there are a few things to you can do to help feel the best possible. These tips include:
- Getting enough sleep.
- Taking all of your medications as directed.
- Getting tested regularly as directed by your healthcare provider.
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Knowing When To Check Your Thyroid
Feel The Bumps And Enlargements
Gently touch the area around your thyroid gland to try to palpate any enlargement, bumps, or protrusions. To differentiate between the thyroid and the other structures of your neck:
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What Do You Need To Know About Thyroid Disease
The most common are autoimmune diseases and iodine deficiency. If your doctor suspects that you have a thyroid disorder, they may recommend one or several blood tests that are part of a thyroid function panel. These tests measure thyroid hormone levels in the blood and can help determine how your thyroid gland is functioning.
Can You Test Yourself At Home
The answer is yes, sort of.
While you can’t draw your own blood to check your thyroid function, you can take advantage of several other strategies designed to tell you how well your thyroid is functioning.
It’s important to realize that these tests are not necessarily more accurate than getting your blood tested, however, so I still recommend that you get your blood work from a physician.
These tests can, however, give you an idea as to whether or not your symptoms are related to your thyroid or to something else.
If you have many of the symptoms of hypothyroidism then you should consider using these tests to determine if you need further testing or treatment.
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Symptoms Of An Underactive Thyroid
Many symptoms of an underactive thyroid are the same as those of other conditions, so it can easily be confused for something else.
Symptoms usually develop slowly and you may not realise you have a medical problem for several years.
Common symptoms include:
- pain, numbness and a tingling sensation in the hand and fingers
- irregular periods or heavy periods
Elderly people with an underactive thyroid may develop memory problems and depression. Children may experience slower growth and development. Teenagers may start puberty earlier than normal.
If you have any of these symptoms, see your GP and ask to be tested for an underactive thyroid.
Read more about getting tested for an underactive thyroid
What Is The Thyroid
The thyroid gland is a small organ thats located in the front of the neck, wrapped around the windpipe . Its shaped like a butterfly, smaller in the middle with two wide wings that extend around the side of your throat. The thyroid is a gland. You have glands throughout your body, where they create and release substances that help your body do a specific thing. Your thyroid makes hormones that help control many vital functions of your body.
When your thyroid doesnt work properly, it can impact your entire body. If your body makes too much thyroid hormone, you can develop a condition called hyperthyroidism. If your body makes too little thyroid hormone, its called hypothyroidism. Both conditions are serious and need to be treated by your healthcare provider.
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Types Of Thyroid Disorders
Why do we even care about thyroid disorders?
Because your thyroid could be considered the “master hormone” in the body which regulates and helps control various other hormones and metabolic functions.
Thyroid hormone is produced through an endocrine gland that sits in your neck.
It produces thyroid hormone which enters the bloodstream and impacts almost every cell in your body.
Small changes to circulating thyroid hormones in the bloodstream may result in big symptoms in your body.
One of the big issues with thyroid related problems is that they are incredibly common with up to 1 in 5 people in the United States experiencing some type of thyroid related issues .
So what types of symptoms might you experience if you have thyroid problems?
The symptoms can certainly vary but because thyroid hormone helps regulate your body weight one of the most common symptoms that patients with thyroid problems experience changes in their weight.
This could be manifested as an increase in weight or a decrease in weight .
Patients also may experience changes to how they tolerate certain conditions such as cold or heat and they may experience cosmetic changes such as hair loss, dry skin, and damage to their nail beds.
The bottom line is that thyroid hormone helps control how you feel on the inside and how you look on the outside – making it one of the most important hormone systems in the body.
Benefits And Limitation Of The Self
An at-home self-exam known as the “neck check” can help you find thyroid lumps or enlargements on your own thyroid gland. These growths may point to any number of thyroid conditions from nodules and goiters to thyroid cancer.
Lumps in the neck can be caused by thyroid disease, and they can also be caused by a variety of other conditions, such as lymph node enlargement, lymphoma, an infectious abscess, or a traumatic injury.
In general, a neck check is not considered the most accurate or reliable way to identify thyroid disease. You can have serious thyroid disease if you have a completely normal neck check. On the other hand, a major growth can often be a sign of an easily treatable condition, such as an iodine deficiency.
In the end, there are limitations as to what a neck check can tell you. A 2017 report from the U.S. Preventive Services Task Force concluded that neck palpation was able to detect thyroid nodules in only 11.6% of cases. Ultrasound, an imaging procedure using sound waves, was five times more accurate in detecting abnormal growths.
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When To See Your Gp
Symptoms of an underactive thyroid are often similar to those of other conditions, and they usually develop slowly, so you may not notice them for years.
You should see your GP and ask to be tested for an underactive thyroid if you have symptoms including:
- tiredness
- being sensitive to the cold
- dry skin and hair
- muscle aches
The only accurate way of finding out whether you have a thyroid problem is to have a thyroid function test, where a sample of blood is tested to measure your hormone levels.
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What Is The Prognosis For People Who Have Thyroid Cancer
Eight out of 10 people who have thyroid cancer develop the papillary type. Papillary thyroid cancer has a five-year survival rate of almost 100% when the cancer is in the gland . Even when the cancer spreads , the survival rate is close to 80%. This rate means that, on average, youre about 80% as likely to live for at least five years after diagnosis as someone who doesnt have metastatic papillary thyroid cancer.
Five-year survival rates for other thyroid cancer types include:
- Follicular: Close to 100% for localized around 63% for metastasized.
- Medullary: Close to 100% for localized around 40% for metastasized.
- Anaplastic: Close to 31% for localized 4% for metastasized.
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