Best Lab Tests for Thyroid Problems


Hypothyroidism Lab Tests and Hyperthyroidism Test

Many people question whether their thyroid is working correctly due to their chronic fatigue, weight gain or foggy thinking. Despite their best efforts to lead a healthy lifestyle, they are still experiencing symptoms that affect their quality of life.

In this article, we’ll explore when and how to order a test for thyroid problems effectively so that you can address thyroid problems & symptoms.


Could You Have a Thyroid Condition?

There is a myriad of symptoms that relate to thyroid conditions. This is why it’s difficult to diagnose a thyroid problem by symptoms alone without proper testing. This article is mainly about lab testing, but I wanted to include a brief review of why you may seek out thyroid testing. For a more in-depth review, please see my previous blog, How To Know if You Have a Thyroid Problem.

  • Increased need for sleep

  • Intolerance of heat or cold

  • Hair loss

  • Can’t lose weight

  • Miscarriage

  • Heavy periods

  • Mood changes

  • Increased sweating or never sweats

The Testing You Need

Thyroid testing is always performed through blood testing. The most common thyroid blood test is performed through one-step direct analog immunoassay for determination of free thyroid hormone. This testing is usually accurate; however, there are some instances in which advanced blood test methods are preferred.

In cases of pregnancy, oral contraceptive use, genetic thyroxine-binding protein abnormalities, heparin use, and in some critical illnesses, techniques such as Liquid Chromatography with tandem mass spectrometry (LC-MS-MS) may be prefered. (1, 2, 3, 4)

The following tests can help you and your practitioner determine:

  1. If you have a thyroid problem

  2. At what point in the thyroid hormone production chain you have a problem

  3. If you have a thyroid autoimmune condition 

  4. Other root causes that could be affecting your thyroid and your energy

Best Thyroid Tests to Order


TSH (Thyroid Stimulating Hormone): “The Trigger”

This is the ‘thyroid hormone’ that is most commonly tested in conventional medicine. TSH is actually not made by the thyroid, but by the pituitary gland to stimulate the thyroid gland. More TSH is released according to a feedback loop, measuring thyroid hormone levels in the body.

A high TSH blood test can indicate insufficient active thyroid hormones, but it’s not enough information to make a useful, functional diagnosis. A low number can indicate hyperthyroidism or thyroid replacement therapy.

You can have hypothyroidism with normal TSH, so keep reading to learn more!

Total T4 (Thyroxine): “The Main Dish”

T4 is the most plentiful product of thyroid hormone production at 80%- 90%. T4 is technically an inactive hormone or prohormone that will need to become biologically active in a later step. Later, 85% of T4 will be converted to T3 by enzymes in the deiodinase system in multiple locations, including the gut, liver, brain, skeletal muscle and thyroid gland. (5

High levels can indicate hyperthyroidism. Lower levels can indicate hypothyroidism. 

Total T3 (Triiodothyronine): “The Sidekick”

T3 is also produced by the thyroid gland per stimulation of TSH, but at much lower levels than T4. It is also created later in the bloodstream and organs by the removal of one iodine atom from the outer ring of T4. T3 is bound to a protein and cannot be used by your cells. 

According to, “ the last test to become abnormal. Patients can be severely hypothyroid with a high TSH and low FT4 or FTI, but have a normal T3.” (6)

High levels can indicate hyperthyroidism. Lower levels can indicate hypothyroidism or Low T3 syndrome. (7

Free T4 (Free Thyroxine): “A More Accurate One”

As you learned earlier, T4 is the most abundant thyroid hormone, but it is mainly bound to a protein and ‘inactive’ as a hormone. About 1% of total T4 is free T4 and available for your cells to use. (8)

Again according to, “Free T4 [testing] avoids any change the proteins could have, giving us a more accurate value for the T4 level.” (9)

High levels can indicate hyperthyroidism. Low levels can indicate hypothyroidism.

Free T3 (Free Triiodothyronine): “The Important One”

Free T3 could be high, indicating hyperthyroidism, but more likely we find it too low. It is important to test all the thyroid markers along the chain of interactions, but I consider free T3 to be one of the most critical markers of thyroid health. 

A robust amount of free T3 can keep you feeling lively and fit, whereas a free T3 at the low end of the range can leave you dragging with nagging symptoms like brain fog and inability to lose weight.

Both free T3 and free T4 can stimulate a cellular thyroid hormone receptor, but “affinity for T3 is approximately 10-fold greater than T4, mak[ing] T3 the most potent TH [thyroid hormone].” (10)

Reverse T3 (Reverse Triiodothyronine): “The Deactivated One”

Reverse T3 is formed by removal of an iodine atom in the inner ring of T4 by an enzyme. Reverse T3 (rT3) in an inactive hormone and a high result on your lab test can mean that the body is not converting enough T4 to active thyroid hormone.

High rT3 values are rare but can indicate a serious illness such as nonthyroidal illness syndrome (NTI). This marker is part of a complete functional thyroid panel but you are unlikely to see it out of range. (11

Thyroid Antibodies: “The Revealing Ones!”

According to a review in ISRN Endocrinology, “AITDs (autoimmune thyroid diseases) broadly include Graves' disease (GD) and Hashimoto's thyroiditis (HT) which are the most common causes of thyroid gland dysfunctions and nonendemic goiter.” (12)

According to, “[Hashimoto's thyroiditis] affects as many as 10 million people in the US alone, and approximately 10% of women over age 30 have Hashimoto's thyroiditis.” (13)

Ten percent of adult women have Hashimoto’s?! It seems incredible, but I see so much in my own practice that I can believe it. 

The reason for this surge of autoimmunity is complex and not fully understood. It’s thanks to a mix of stress, immune weakness, genetics, gut permeability, food quality and toxins in the environment. You are also more vulnerable to Hashimoto’s post-partum and as you move into menopause. For the purpose of this article on labs, we won’t open that can of worms too much! (14, 15, 16, 17)

The point here is that autoimmunity is the most common cause of thyroid conditions, so we’d better test for a Hashimoto’s disease diagnosis (which can officially only be made by a physician)!

The most common autoimmune thyroid disease is Hashimoto's thyroiditis, so it’s what we most commonly test for. We’ll cover the two antibodies for the Hashimoto’s test first:

  • Thyroid Peroxidase Antibodies (TPOAb) - Thyroid peroxidase (TPO) is an enzyme normally found in the thyroid gland that plays an important role in the production of thyroid hormones. A TPOAb test detects antibodies against TPO in the blood. (18)

  • Thyroglobulin Antibodies (TgAb)- This antibody attacks a protein, thyroglobulin, needed for thyroid hormone production.

The other autoimmune condition associated with the thyroid is called Grave’s disease. Grave’s disease presents more symptoms of hyperthyroidism, such as rapid heartbeat, sweating, and rapid weight loss. It is possible, but uncommon, to have both Grave’s disease and Hashimoto’s. If you suspect you have Grave’s disease, ask your practitioner for the following hyperthyroidism test:

  • Thyroid Stimulating Hormone Receptor Antibodies (TRAb)- The antibody attacks the Thyroid Stimulating Hormone (TSH) receptors within the thyroid gland. The “TRAb overrides the normal regulation of the thyroid, causing an overproduction of thyroid hormones [hyperthyroidism].” (19)

Other Helpful Blood Tests

Getting your blood drawn is not the most fun thing to do, so while we are at it I like to add on a Complete Blood Count (CBC) and test for vitamin D. These are pretty affordable add-ons that can give us further information.

A CBC is a very usual screening with a lot of markers, so I’ll just cover a few highlights, along with information on vitamin D, below.

25-hydroxy vitamin D

A vitamin D deficiency can lead to immune dysregulation, autoimmunity, blood sugar dysregulation, anxiety and more. It’s important to know your personal vitamin D level, know the optimal level, and supplement and retest as needed. (20)

Fasting glucose and HA1C

These two markers of blood sugar are a great snapshot of your short and long-term blood sugar levels. As many people dealing with hypothyroidism are also dealing with brain fog, headaches or excess weight, we want to know if blood sugar is too high.

WBC (White Blood Cell Count)

As you may know, some gut infections are associated with Hashimoto’s thyroiditis. While a blood test won’t directly tell you if you have a gut infection, we can get a sense of how your immune system is faring if your WBC is too high or too low, and if certain cell type percentages are off. 

Two known infections associated with Hashimoto’s are blastocystis hominis parasitic infection of the large intestine and H. pylori bacterial infection of the stomach. (21) Optional is further testing for gut infections through a stool test with us.  

RBC (Red Blood Cell Count) & Ferretin

Red blood cells transport oxygen to your cells for energy and brain function, among other things. If you are anemic, you are can be chronically fatigued and breathless. 

Anemia can occur in older adults or hypothyroid individuals as stomach acid levels decrease and digestion and assimilation of nutrients are not as strong. 

The breakdown of your RBC values can let us know if you may have B12 deficiency or iron-deficient anemia.

Ferritin is a measure of stored iron. Too little can mean your low on iron which may contribute to chronic fatigue. Too much may indicate inflammation, cell damage or liver disease. (22, 23, 24)

Why Testing with Your MD May Fall Short

I meet many, many clients who suspect a thyroid problem, but have had incomplete testing, or have had no one to help them interpret their results correctly. 

I used to own an integrative wellness center that accepted health insurance. There were many benefits to this system, but I’m also aware of some of the drawbacks of this system.

If your primary care practitioner is not versed in autoimmune disease and a functional medical approach to thyroid management, they may not be able to order a complete thyroid panel as outlined above. Much of their time and ability to bill insurance is dictated by insurance guidelines.

Even if your practitioner is open-minded to your request and orders tests for you, they may not be able to interpret it for you in the way you hoped for. 

How to Test Right and Restore Your Health

The good news is that nowadays, in most U.S. states you can order tests yourself online, which is awesome! The drawback to this system is that you may not know how to interpret the test, or the best, customized protocol to improve your health.

I’ve been wanting to address the problem of incomplete thyroid testing in our community for a while now, and am thrilled to say that we now have a solution for you!

Introducing our Thyroid+ Testing and Review! This combination of pre-paid local lab testing and a private online consultation with our team will:

  • Ensure you get the tests you need

  • Check for Hashimoto’s thyroiditis

  • Find out exactly at what point your thyroid levels go sideways

  • Learn your vitamin D levels

  • Get insight into possible infections

  • Learn if your blood sugar is too high

  • Learn if you have any hidden causes of fatigue

  • Get your questions answered by a functional expert

  • Get a customized supplement recommendation

  • Get access to our Client Library, with quick guides to detox, weight loss, PCOS & more

  • Help you receive further testing that your coach recommends, if applicable to your health complaints

  • Get a 10% coupon to our shop, for both supplements and further labs!

All for just $397, including the price of the labs! It’s taken me a while to develop this package with so much at such a great price point, and I think you’ll be very happy with the result.

For a deeper insight into your health, including an in-depth digestive and hormonal review, please see our “Big Three'“ testing package below.

I’ve also been keen to add an ‘ultimate testing package’ that would cover many root cause issues for you all at once. We call it the “Big Three” package.

This new offering includes:

  • All the thyroid testing above

  • A GI Map stool test for gut health 

  • A DUTCH test of hormones

  • A 90-minute functional lab review to go over all three

  • A customized protocol just for you

We discussed the thyroid package above, and you’ll get all those same benefits. Here are some highlights of the DUTCH test and GI-MAP:

The DUTCH test reveals:

  • The health and output of your adrenal glands

  • Your levels of testosterone, estrogen and progesterone 

  • Levels of some nutrients such as B6, B12 and glutathione

  • Estrogen metabolite ratios (relate to cancer risk)

  • Methylation activity (marker of detoxification)

The GI-MAP test reveals:

  • Parasite and worm infections

  • Candida and H. pylori infections

  • Bacterial health of the large intestine

  • Markers of pancreatic health (enzymes) and fat digestion

  • Marker of beta-glucuronidase (marker of estrogen and phase 2 detox)

  • Zonulin (marker of leaky gut and leaky brain)

If you are ready to get to the root of your chronic fatigue, brain fog, bowel issues and more, check out the Big Three package! You’ll be so glad to finally get the root of your symptoms and have a clear plan to move forward.!

Have you had your thyroid tested before? What have you learned? Share your thoughts in the comments below!


Bridgit Danner, LAc, FDNP, is trained in functional health coaching and has worked with thousands of women over her career since 2004. She is the founder of Women’s Wellness Collaborative llc and

Check our her easy 5-Day DIY Detox Guide here!