Thyroid Blood Tests-What They Tell You

By Corri Peterson

Thyroid blood tests should be the first laboratory tests run by your doctor if you are experiencing weight gain, fatigue, or moodiness. The thyroid gland is a member of the endocrine system.

Thyroid Blood Tests

The endocrine system is a network of glands that produce hormones. These hormones act like a messenger system regulating all the functions in your body.

One of those hormones produced is the thyroid hormone which controls your metabolism and regulates every other body function. If you don’t have enough thyroid hormone, (If you purchase through the links in this post, we may receive a commission) everything moves more slowly.

Your heart rate is slower, you may get constipated, and you may gain weight. If you have too much thyroid hormone, everything speeds up. You may have diarrhea, your heart might race, or you may lose weight.

Thyroid Hormone Levels Affect Several Functions-

Here are a few areas affected by thyroid hormone:

  • Metabolism (the way you break down food and get energy from nutrients)
  • Growth and development
  • Emotions and mood
  • Fertility and sexual function
  • Sleep
  • Blood pressure

It doesn’t matter your age; stress, infections, and exposure to certain chemicals can mess with your endocrine system. In addition, genetics or lifestyle habits can increase your chances of an endocrine disorder like hypothyroidism, diabetes, or osteoporosis.

Statistics state as many as 20 million Americans suffer from thyroid dysfunction, with up to 60 percent unaware of their condition.

Women are diagnosed up to 8 times more often than men, with one in eight women developing a thyroid issue in her lifetime.

Common Symptoms of Thyroid Dysfunction-


Increased sensitivity to cold


Dry skin

Weight gain

Puffy face


Muscle weakness

Elevated blood cholesterol levels

Muscle aches, tenderness, and stiffness

Pain, stiffness, or swelling in your joints

Heavier than usual or irregular menstrual periods

Thinning hair

Slowed heart rate


Impaired memory

Enlarged thyroid gland (goiter)

Weight gain and fatigue are probably the two most cited symptoms of thyroid issues when seeing a healthcare provider.

Thyroid Blood Tests

Many times those seeking relief from anxiety, depression, mood swings, or memory issues have no idea it’s their thyroid that’s to blame.

The Thyroid’s Long History

Thyroid disease has a long and ongoing history. William Gull first explained adult hypothyroidism in 1874 during a speech to the Clinical Society of London. A few years later, William Ord used the term “myxedema” to describe the edema he observed in some hypothyroidism patients. Ord’s observation was followed up by the first reported effective treatment of hypothyroidism—with sheep thyroid extract—by George Murray in 1891.

After reviewing the relationship between psychosis and hypothyroidism, Richard Asher, a British endocrinologist, added the terminology “myxedema madness” to the literature in 1949. Since then, case studies have continued exploring and reporting on the physical and psychiatric consequences of hypothyroidism.

If you feel like something is off you may have a thyroid problem, you should request thyroid testing. Thyroid disease symptoms can make you feel as if you are crazy; however, replacing and rebalancing your hormones, replenishing depleted nutrients, and reducing exposure to thyroid-disrupting chemicals will ease symptoms and improve thyroid function.

Common Thyroid Blood Tests

Most doctors start by testing your TSH (thyroid-stimulating hormone) levels. However, unless there are obvious symptoms, like nodules or swelling, you will be limited to the testing you receive. The reason is that most insurance companies will only pay for TSH testing unless there are symptoms to support additional tests.

Here is a list of the tests available for thyroid diseases:

TSH-(thyroid-stimulating hormone)-

Reference range- 0.5-4.70 mIU/L FYI- Some labs have upper limits of 8-10 mIU/L

TSH made in the pituitary gland tells the thyroid how much T4 and T3 to make. Generally, high TSH levels mean hypothyroidism (underactive), and low TSH levels indicate hyperthyroidism (overactive).

Total T3-(triiodothyronine)-

Reference range-80-200ng/dl 

This thyroid hormone regulates your digestive and metabolic function and supports bone health. 

Free T3-(free triiodothyronine)-

Reference range-2.3-4.2pg/ml 

It’s the T3 hormone that doesn’t bind to proteins and circulates unbound in your blood. So it’s an active type of hormone.

This ratio of Free T3 to Reverse T3 tells the provider how effective the conversion from T4 to active T3 is.

RT3-(reverse T3/reverse triiodothyronine)- Reference range-10-24 ng/dl

A high reverse T3 level indicates you are converting most of your T4 into reverse T3. Reverse T3 is a variant of T3.

Total T4- (thyroxine)-Reference range-4.5-12.5ug/dl

A high level of T4 may point to hyperthyroidism, while a low level of T4 may point to hypothyroidism. Since certain medical conditions and medicines affect T4 levels, many doctors prefer to measure freeT4 levels.

Free T4-(free thyroxine)- Reference range-0.8-1.8ng/dl

Reference range-0.8-1.8ng/dl Since this hormone is not affected by medicines or conditions, many providers prefer to check these levels.

Thyroid Blood Tests

Testing For Autoimmune Diseases

TPOAb- (thyroid peroxidase antibodies- Reference ranges-0-35iu/ml

These antibodies are linked to the hypothyroidism observed in Hashimoto’s.

TgAb (thyroglobulin antibodies)- Reference ranges-0-4.0iu/ml

For those who had surgery to remove their thyroid, thyroglobulin levels are checked to determine whether any tumor (cancer) is left or if any thyroid remains.

TSI-(thyroid-simulating immunoglobulin antibodies)- Graves’ disease- Reference ranges-0-1.3

This test measures the amount of thyroid-stimulating immunoglobulin in your blood. These antibodies tell the thyroid gland to release excess amounts of thyroid hormone into the blood. These antibodies are consistent with Graves’ disease.

Tg-(thyroglobulin)- No thyroid gland: 0-0.1 ng/ml Still have a gland:0-33ng/ml

This test is completed after a patient has had the complete removal of their thyroid. The Tg level in the blood sample verifies whether there is any cancerous tumor left behind.

The Four Basic Types of Thyroid Disease

NON-AUTOIMMUNE HYPERTHYROIDISM-The thyroid is overactive and produces excessive thyroid hormone. A few causes of hyperthyroidism are thyroiditis, thyroid nodules, benign thyroid tumors, infections, and some medications. Other triggers may include liver dysfunction, heavy metal toxicity, and nutritional deficiencies.

GRAVES’ DISEASE AUTOIMMUNE HYPERTHYROIDISM-This autoimmune disease causes the body to produce an antibody called TRAb. This antibody binds to your thyroid receptors, causing your thyroid gland to release more T4 hormone than the body needs.

Many times, treating inflammation and any infections will be part of Graves’ and Hashimoto’s patients’ treatment plan. 

NON-AUTOIMMUNE HYPOTHYROIDISM- For those who are dealing with non-autoimmune hypothyroidism, there are more causes than you realize. Like hyperthyroidism, hypothyroidism can also be caused by liver dysfunction, heavy metal poisoning, and nutritional deficiencies. Other ailments associated with hypothyroidism are depression, Chronic Fatigue Syndrome, Fibromyalgia, chronic stress, and chronic pain.

HASHIMOTO’S THYROIDITIS- This autoimmune disease produces the antibodies thyroglobulin (TgAb) and thyroid peroxidase (TPOAb). These antibodies cause the thyroid to stop producing hormones and die. This disease can cause your thyroid to make too many hormones; then, as your thyroid loses function, it makes fewer hormones. Yes, Hashimoto’s is like taking a huge roller coaster ride.

Thyroid Blood Tests

Thyroid Hormone Replacement Options

Levothyroxine/T4- The standard of care treatment for hypothyroidism is a daily dose of synthetic thyroxine(T4), referred to as L-thyroxine or L-T4. FYI– Levothyroxine is the most prescribed thyroid hormone replacement.

Synthroid- The brand name of the synthetic compound T4 (Levothyroxine) used to treat hypothyroidism.

Levoxyl- This hormone was pulled from the market in 2013 due to a suspicious odor from the packaging. This recall caused Levoxyl to be off the market for about a year, so many consumers changed to alternatives. As a result, Pfizer lost their share of the market.

Levothroid- A generic T4 hormone that is no longer manufactured.

Tirosint (hypoallergenic, liquid capsules)-The brand name for Levothyroxine is designed for people with allergies to fillers and dyes found in traditional formulations. These soft gel capsules contain no dyes, gluten, alcohol, lactose, or sugar. In addition to T4, Tirosint contains only three inactive ingredients: gelatin, glycerin, and water.

Liothyronine/T3- The synthetic version of the T3 thyroid hormone.

Cytomel- The brand name for Liothyronine.

Compounded Hormones- These prescriptions combine T3 and T4 into a single dose, allowing your body to use the T3 and convert the T4 as needed. These prescriptions are only available at a compounding pharmacy.

Natural Thyroid Hormones

They are also known as natural desiccated thyroid (NDT) or porcine thyroid. Before the pure levothyroxine availability, desiccated animal thyroid extract was the only treatment for hypothyroidism.

Some patients who continue to have hypothyroidism symptoms while taking levothyroxine report improvement in those symptoms when switched to desiccated thyroid extract.

Armour thyroid- This hormone replacement was in the news when Hilary Clinton was running for president. Her doctor prescribed Armour Thyroid rather than Levothyroxine (Synthroid) to treat Clinton’s hypothyroidism.
Two comments were linked to the news report:
1) “Armour Thyroid. One would think we could do better for our former First Lady,” wrote one commenter.
2) “I am glad to hear she is taking Armour Thyroid rather than synthetic substitutes, which contain only T4 and not T3. I always prescribed Armour for my patients because it is more natural, safer, and more effective,” wrote another.

Nature-throid, WP Thyroid-

Natural Desiccated Thyroid (NDT) drugs, including Armour Thyroid, Nature-Throid, NP Thyroid, and WP Thyroid, have been around for decades and remain popular with alternative, holistic, and integrative physicians.
Many patients feel much better on a natural thyroid medication that contains T3 and T4 and some amounts of T2, T1, and Calcitonin. Many patients feel much better, have more energy and relief of symptoms when switching from synthetic to natural thyroid.

ERFA Canada- Similar to Armour Thyroid. This desiccated thyroid replacement hormone is only available in Canada.

When starting on thyroid hormone, you start on a lower dose, with that dose increased every month or two until your hormones have returned to their proper levels and your symptoms are under control. 

Thyroid Blood Tests

Thyroid Doctor Choices-

Finding a doctor to treat your thyroid dysfunction can be a challenge, but you can find a doctor who will help you feel better with a bit of knowledge. I have listed the types of doctors available to treat thyroid problems and shared the kinds of care they provide.

The first five doctors I list are conventional physicians. They are the ones you will see when going to most hospitals or clinics. They will follow the “standard of care” treatment plan. The insurance companies and the CDC compile these treatment plans, so your health plan may not cover specific tests and medications.


These are the specialists. These are the doctors you will be referred to when your primary doctor doesn’t know how to treat you or need more targeted or specialized treatment.

FYI: diabetes is the most diagnosed endocrine disease, so many endocrinologists out there mainly treat diabetes. They may have limited knowledge when treating thyroid disease. 


The eye specialists. If you have Graves’ disease or other issues affecting your eyes, you see one.

Primary care physician

For many, this is your primary doctor if you have one. In addition, some insurance plans require a primary care doctor. These are the same as an internist or family practice physician.


These doctors care for adults. They are similar to primary care doctors.

Family practice physician-

These physicians are a combination of internists and pediatricians. They care for adults and children.

Natural Medicine

The following list of physicians focuses on natural medicine and nutritional methods to heal the body and ease symptoms when dealing with thyroid disease. These four doctors concentrate on healing the whole body while using as few medications as possible.

Naturopathic Physician-

These doctors use natural medicine along with conventional diagnoses and treatments. They address the causes, work on prevention, and teach healthy living.

Functional medicine physician-

These doctors focus on getting your body to work together, including the endocrine, immune and digestive systems.

Paleo physician-

These doctors follow our ancestor’s diet. It consists of whole meat, fish, eggs, vegetables, fruits, nuts, and seeds—no processed food. Nutrition is the main focus for healing.

Holistic medicine physician-

These doctors treat the physical, mental, spiritual, and emotional needs of the whole person. In addition, they focus on improved nutrition and avoiding chemicals that harm the body.

As you can see, there are several choices for finding a healthcare provider who will meet your needs. First, you want to find a doctor who practices healthcare the way you want to live your life.

That being said, I know many who have thyroid disease have problems finding a health care provider who understands the symptoms and how to treat them.

According to Mary Shomon, a thyroid patient advocate, thyroid disease is viewed as an “easy to test, easy to treat, take a pill, and you’re better” condition by many conventional doctors. Unfortunately, this attitude has many who continue to suffer from symptoms seeking alternative medicine options.


Keep in mind these adjustments to my care plan only happened with my functional medicine doctor.

Work with your provider to optimize your TSH, free T4, and T3 levels, not just in the normal range. They need to be optimal for you, so the majority, if not all, of your symptoms are controlled.

For example, my TSH is 0.023 IU/ml and is flagged by the laboratory as low. The lab lists their reference ranges as 0.045- 5.330. 

My free T4 is 1.07, with the reference range of 0.61-2.00, and my free T3 is 3.1 with the reference range of 2.5-3.9, which is excellent. However, if my TSH levels get higher, it throws off the free T4 and T3 levels, and I have symptoms. 

My current doctor and I have discussed how a low TSH result would send many, if not all, conventional doctors into a panic, but my body responds the best at those levels, and he understands that. He has also told me that those who have had all or most of their thyroid removed or destroyed feel better with a lower TSH level. He is a functional medicine doctor, so his focus is getting my whole body in sync.

Also, don’t be afraid to change medications. Different brands have different ingredients. Some will feel better on synthetic brands, while others will feel better on natural hormones. For example, Levothyroxine is a synthetic hormone; it contains only the T4 hormone. Many doctors will tell you that since your body will convert T4 to usable T3, you will have no problems taking Levothyroxine. However, many thyroid patients lose the conversion capability, leaving them with uncomfortable symptoms.

FDA-Approved Medications

One thing to note here: all thyroid hormone medications are FDA regulated and are safe for consumption. Don’t let anyone tell you that natural hormones like Armour Thyroid are unsafe, unregulated, and the doses vary from pill to pill. This is not true. Statistics show that 50% of thyroid patients report fewer symptoms when taking natural hormones compared to Levothyroxine. So I am clear about this– I am not talking about the thyroid supplements available online. I am referring to prescription hormone replacement only. These are FDA-approved.
When I switched from Levothyroxine to Armour Thyroid, the constant cold feeling went away. Just remember: if one brand of hormone is not controlling your symptoms, try another. You do not have to suffer!

Thyroid Blood Tests

-Supplement any vitamin B, D, and magnesium deficiencies. These also contribute to fatigue, so supplementing them is vital!
Thyroid disease depletes your body of certain nutrients, so supplementation is crucial to healing and symptom control. But, as mentioned before, your diet alone won’t be able to meet those needs.

-Check for gluten intolerance and food allergies. Nutrition plays a significant role in dealing with and healing thyroid issues.

-Improve gut health and digestion. My doctor started me on two different Probiotics and recommended that I add one tablespoon of Diatomaceous earth to water and drink it once or twice a day. He said the earth scrubs the lining of my intestines for better nutrient absorbance. The funny thing is I feel so much lighter when I drink my dirt!

If you are having problems finding a health care provider, whether it’s wanting to try a different medication or having additional testing done, you can order lab tests online. Several laboratories offer to test online, and doctors can interpret your results online, over Skype, or via email. 

I know several who have had their tests done through online providers, with reports of thorough treatment plans with excellent results.

Please don’t give up. There is relief available. Sometimes it takes searching to find that relief. I went through six different doctors before finding the functional medicine doctor that listened to my symptoms and set up a treatment plan that controls them and heals my body.

Take care,



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