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High TSH & Normal T4: What Does it Mean? + Other Thyroid Lab Patterns

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Are you experiencing a high TSH but normal T4?

Are you confused about interpreting these values?

Is your Doctor telling you that your tests are normal even though you are experiencing abnormal symptoms?

This article will help shed light on this thyroid lab pattern and help you understand what it means. 

You’ll learn more about the symptoms associated with this pattern (and other patterns) and how to treat them below : 

Is This Thyroid Lab Testing Pattern Bad?

The first thing you should know is that having a high TSH, even if accompanied by a normal T4, is never a normal sign. 

A high TSH is a marker that the connection between your brain and your thyroid may not be functioning at 100%. 

What do I mean?

In order to understand this concept, you have to understand how TSH functions in your body. 

TSH (also known as thyroid stimulating hormone) is a hormone that is produced by the pituitary gland. 

Its job is to act on your thyroid gland (in your neck) to tell your thyroid to produce more thyroid hormone. 

If your TSH is elevated this means your brain is trying to increase the “stimulus” to your thyroid gland in an attempt to compensate for decreased thyroid hormone (1).

This process is how your brain and your thyroid gland regulate thyroid hormones in your blood. 

As thyroid hormones drop your TSH will rise to compensate to tell your gland to produce more. 

This rise in TSH is almost always seen as an early and sensitive marker for thyroid dysfunction! 

So, while TSH tells you how responsive your thyroid gland is to thyroid hormone it doesn’t give information on your free thyroid hormone levels. 

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What your Free Thyroid Hormones Mean for You (Free T3 & Free T4)

Most physicians (Doctors) tend to order what is known as a TSH with reflex to free T4 . 

This lab test is supposed to only order the free T4 IF the TSH is abnormal (2).

The idea is that it saves on the cost of unnecessary lab tests because why would you need to see the free T4 if the TSH is normal? 

So, what ends up happening, is many patients get their thyroid “checked” which results in this TSH with reflex to free T4. 

When they find that their TSH is abnormal the lab company will automatically order free T4. 

But they might get confused when the free T4 comes back as “normal” or within the normal range. 

How can this be if your TSH is high?

Several things may account for this phenomenon. 

#1. Your thyroid gland is struggling but still able to keep up… for now . 

The rise in your TSH is a normal physiologic response for lower-than-normal free thyroid hormones and it indicates that everything is working properly. 

But as TSH rises it means that your thyroid gland is no longer responsive to the lower doses of TSH that it once was. 

This usually indicates an early problem with the thyroid gland itself. 

Because your thyroid gland is getting the stimulus from the brain to produce more thyroid hormone (hence the high TSH) but it’s only capable of producing a “normal” amount of T4. 

We know this because we know what a HEALTHY TSH level is supposed to be (3).

We also know that a high TSH is not necessary to produce adequate thyroid hormones. 

So this early rise in TSH can be used as a sensitive marker for early thyroid GLAND dysfunction. 

By the way, you may find that both your free T3 and free T4 stay “normal” despite having a very high TSH. 

This is seen as your body is attempting to compensate for the early problems described above but it does NOT mean that this is “normal”. 

Eventually, your thyroid will be unable to meet the demand and you will experience severe symptoms (if you aren’t already) . 

#2. The lab tests may not be accurate . 

This one is rare but it certainly does happen. 

It is estimated that up to 5% of all lab tests may be inaccurate or spurious. 

This is as high as 1 in 20 lab tests and if you get a full panel of lab tests you can count that at least a few of those results are not 100% accurate. 

This inaccuracy stems from the fact that lab testing machines must be calibrated to normal each and every day. 

If there is something wrong with the machine for one test or the calibration is not done accurately, then some of the lab tests may not be accurate. 

So what should you do if you feel that your results are not accurate?

The best thing to do is to simply re-test your TSH and free T4 within 1-2 weeks. 

The chances of your lab tests being inaccurate are very low, but it’s worth going through this song and dance if you don’t have any symptoms and feel great. 

#3. You may have Hashimoto’s Thyroiditis . 

Another possibility is that you have an autoimmune disease known as Hashimoto’s thyroiditis . 

It is well known that this thyroid condition can cause changes to thyroid lab tests which are not considered to be “normal” (4).

In fact, many patients with Hashimoto’s are not treated sufficiently because their symptoms do not always correlate with their lab results. 

When in doubt, make sure that you always look at your body and your symptoms and don’t focus solely on your lab tests. 

If you suspect that you may have Hashimoto’s you can easily check for this condition with a blood test which checks for thyroid antibodies. 

#4. You may not be converting T4 to T3 . 

Lastly, it’s possible that you may not be seeing the “whole picture” when it comes to your thyroid. 

While your TSH and free T4 are important measures of thyroid function they do not test every facet of thyroid function in your body. 

One of the most important (if not the most important) lab test to look at when it comes to your thyroid is known as free T3 . 

Free T3 is the ACTIVE thyroid hormone and it is created through a process known as thyroid conversion . 

In this process, your body takes free T4 and turns it into free T3. 

So, why does free T3 matter? 

Consider this scenario:

Imagine that your TSH is high and your free T4 is normal but you decide to check your free T3 as well. 

You may find that your free T3 is actually quite low which indicates that your body can produce some amount of T4 but it’s not able to convert that T4 into T3. 

This is known as a problem with thyroid conversion and can be entirely missed unless you also check for your free T3 .

For this reason, I always recommend that you look at a complete thyroid panel (if you suspect you have thyroid disease). 

If you didn’t get a full thyroid panel to start with you can always go back and get everything retested. 

Symptoms Associated with a High TSH

Will you have symptoms if you have a high TSH and a normal T4?

You might expect that you would be without symptoms if your free thyroid level is “normal” but that isn’t always the case. 

In fact, most patients with a high TSH (regardless of their free thyroid hormone levels) may be symptomatic. 

A handful of patients may be asymptomatic (meaning they won’t experience symptoms) most likely due to their body having a “reserve” level which can keep them going for some time. 

But, if you are like most people, you may start to experience certain symptoms. 

In fact, these symptoms may be the reason you went to your Doctor in the first place and had your blood work checked. 

The symptoms associated with a high TSH are easy to identify because they are the symptoms of low thyroid function or hypothyroidism. 

Symptoms of a high TSH and normal T4 include:

• Mild weight gain (usually no more than 2-5 pounds)
• Cold intolerance or feeling like you are cold all the time
• Mild constipation
• Feeling “down” or “depressed”
• Mild brain fog or clouded thinking/judgment

The degree of symptoms that you will experience will depend on the degree of elevation of your TSH (5).

Put simply:

The higher your TSH, the more your thyroid gland is compromised and the more severe your symptoms will be.

So, you may experience only mild weight gain if your TSH is in the 3-5 range, but that weight gain will be more severe if your TSH is 5-10, and so on. 

These symptoms are an indication that your thyroid is NOT functioning properly and are a sign that you should seek out therapies to try and fix the problem. 

Treatment Options + What to do next

So what should you do if you have a high TSH? What therapies are available to you?

The first thing you should do is to make sure that your test results are indeed legitimate. 

That means that your lab results should match your clinical appearance. 

If you are completely asymptomatic, meaning you are not experiencing any of the symptoms listed above, then it may be reasonable to simply recheck your blood work in 6-8 weeks to see if your test was accurate. 

If you are symptomatic, however, then you can safely assume that your thyroid is not functioning appropriately. 

This would be an indication that some sort of intervention is warranted. 

In terms of the type of treatment available you really have a couple of options: 

#1. Treatment with thyroid medication

The most common treatment for a high TSH is to take thyroid hormone replacement medication. 

This medication, usually in the form of T4 such as Levothyroxine , will help supplement your body with extra T4 which will, in turn, drive down your TSH to normal levels . 

This is the theory behind using thyroid medication to help if you have thyroid dysfunction. 

The problem is that not everyone will do well on T4-only thyroid medications (even though they are the most commonly prescribed). 

Previously, I mentioned that you may have an issue with thyroid conversion which leads to low free T3. 

If you fit this category then you may need to use a thyroid medication that contains both T4 and T3. 

These therapies should always be combined with #2…

#2. Treatment with Alternative Therapies Including Diet and supplements. 

These therapies shouldn’t be considered “alternative” at all because they are really the single best way to improve your thyroid and other hormones. 

Using basic therapies which include eating a more healthy diet, taking vitamins and nutrients which you may be deficient in, and exercising regularly should never be ignored if you have a thyroid issue!

Study after study has shown that these therapies do indeed help to reduce inflammation (6) and promote hormone balance (7).

The problem is that many patients forgo these therapies in favor of taking medications!

This behavior only reinforces future problems and never actually allows your body time to improve. 

In terms of your diet, you can read more about the type of healthy foods you should be eating in this article . 

For supplements, you’ll want to focus on nutrients and vitamins which have been shown in scientific studies to improve your thyroid. 

I recommend a supplement such as this one which contains all of these nutrients . 

In addition to these therapies, you’ll also want to ensure that you are sleeping 8 hours each night and managing your stress appropriately!

Doing these things, in conjunction with thyroid medication (if necessary) will go a long way toward helping you feel better. 

What if you have a High TSH and a Low T4?

Does anything change if you have a high TSH and a low T4 or low T3? 

The answer is no. 

The difference between those who have a high TSH and a low or normal T4 likely has to do with their “reserve capacity” for thyroid function. 

In other words, some people are probably able to tolerate different levels of T4 without becoming symptomatic due to either the number of thyroid receptors they have on their cells or due to receptor sensitivity (they may be more or less sensitive to thyroid hormone than you). 

So, don’t be too concerned with your absolute T4 or T3 level, instead, try to focus on whether or not you have both a lab abnormality combined with symptoms. 

The combination of these two factors will give you the most information and help you zone in on a diagnosis. 

If you have low T4 you can read more about that condition here . 

Other Thyroid Lab Patterns which May Result in Hypothyroid Symptoms

Are your lab tests slightly different than what we discussed here?

Don’t worry!

I’ve included a list of various other lab tests below and how they may present in terms of your symptoms:

• High TSH, normal T4, normal T3 = This is the pattern we’ve been discussing in this post and will usually present with hypothyroid symptoms. 
• High TSH, normal T4, low T3 = This pattern may be an indication that you are having issues with thyroid conversion and most often presents with hypothyroid symptoms. 
• Normal TSH, low T4, low T3 = This pattern is usually what is seen in those with chronic illness and in those who are taking multiple medications. If you have this pattern you will most likely be symptomatic. 
• Normal TSH, normal T4, low T3 = This pattern may be consistent with low T3 syndrome or euthyroid sick syndrome and may present with hypothyroid symptoms but not always. 
• Normal TSH, normal T4, normal T3, positive thyroid antibodies = This is a classic presentation for early Hashimoto’s, and most patients with this pattern will be symptomatic. If you are symptomatic this is a valid reason to consider a trial of thyroid medication even though your lab tests are “normal”. 
• Normal TSH, normal T4, normal T3, high reverse T3 = This pattern is most often seen immediately after calorie restriction or after dieting and weight loss. This pattern usually indicates an adaptive response from your body and one that shows your metabolism will be slowing over the next few months (not ideal for weight loss). 

This isn’t a comprehensive list of all of the thyroid patterns available, but it should really give you a good starting point if you aren’t sure where you “fit in”. 

Lastly, if you have any questions about your labs feel free to leave a question or a comment below and I can try to direct you further! 

The bottom line?

Your TSH and your free T4 are connected and changes in one will often time result in a change in the other. 

Don’t let a single “normal” lab result in a sea of abnormal results alter how you look at your thyroid lab tests. 

It’s not abnormal for one result to be “normal” even though many others are obviously abnormal. 

Lastly, make sure that you listen to your body and your symptoms. 

You are more than just your lab results!

Now I want to hear from you:

Do you have a high TSH with a normal T4? 

What about your free T3 levels?

Have you had a complete thyroid lab panel?

Leave your questions, comments, or answers below! 

#1. https://www.ncbi.nlm.nih.gov/pubmed/402379

#2. https://www.ncbi.nlm.nih.gov/pubmed/28938415

#3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3245392/

#4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3075814/

#5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1497160/

#6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3629815/

#7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4811358/

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About Dr. Westin Childs

Hey! I'm Westin Childs D.O. (former Osteopathic Physician). I don't practice medicine anymore and instead specialize in helping people like YOU who have thyroid problems, hormone imbalances, and weight loss resistance. I love to write and share what I've learned over the years. I also happen to formulate the best supplements on the market (well, at least in my opinion!) and I'm proud to say that over 80,000+ people have used them over the last 7 years. You can read more about my own personal health journey and why I am so passionate about what I do.

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This content is strictly the opinion of Dr. Westin Childs and is for educational and information purposes only. I go to great lengths to help my users better understand their health; however, the content you see here is not a substitute for medical advice. If you have questions regarding your health you should seek qualified information from a medical professional or your doctor.

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What are T3 and T4: The Complete Guide to Your Thyroid Hormones

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T3 and T4 are hormones that are secreted by your thyroid gland and have a major impact on your health. T4 is the thyroid hormone thyroxine and T3 is the hormone triiodothyronine, and they affect almost every organ in your body. T4 and T3 levels in your body are regulated by the thyroid-stimulating hormone, or TSH for short. Thyroid tests to check thyroid function usually check for abnormal levels of TSH and T4 hormones.

Symptoms of hypothyroidism (underactive thyroid) are usually associated with low levels of T4 and T3. This can cause you to feel fatigued, have difficulty losing weight, feel tired, and have hair loss. An underactive thyroid is also associated with high TSH levels and low T4 levels.

An overactive thyroid or hyperthyroidism is caused by high T4 and T3 levels in your bloodstream. When your thyroid secretes too much thyroid hormones you can feel restless, suffer from sleep problems, have frequent digestive upset, and increased sweating. If you suffer from hyperthyroidism, your thyroid test results will usually show low levels of TSH hormone .

This article contains a complete guide to your thyroid hormones and thyroid function. You will learn what T4 and T3 hormones do in your body and what the target range of T3 and T4 is. I will also explore why testing for free T4 levels is sometimes better than a TSH blood test.

The Thyroid Gland and What it Does

Your thyroid is an important hormonal gland in the body that has a direct impact on your metabolism. Your thyroid sits in the front part of your neck just below your voice box and is shaped like a butterfly.

Dr. Carol DerSarkissian on WebMD says that the thyroid releases hormones into the bloodstream. Your thyroid releases triiodothyronine (T3), thyroxine (T4), and calcitonin (produced by the parathyroid glands). From these, Dr. DerSarkissian says that T4 is the main hormone that affects growth, metabolism, and brain development. 1

What is TSH?

Your thyroid function depends on hormones that are released by glands at the base of your brain. The hypothalamus releases thyrotropin-releasing hormone (TRH) which then stimulates the pituitary gland. The pituitary gland then secretes TSH that stimulates the thyroid to produce T3 and T4 hormones which are released into your bloodstream.

Doctors from the Cleveland Clinic explain that TSH levels can fluctuate depending on T3 and T4 levels in blood serum. For example, if your thyroid doesn’t produce enough thyroid hormones (underactive thyroid), messages are sent to your pituitary gland to increase TSH levels. On the other hand, high levels of T4 and T3 hormones caused by an overactive thyroid can signal your brain to lower TSH. 2

The journal Frontiers in Endocrinology describe this connection between T3, T4, and TSH as a feedback loop. Doctors say that TSH testing may not be the most accurate way to monitor thyroid health if you receive T4 thyroid replacement therapy for hypothyroidism . 3

What are T3 and T4?

T3 is the thyroid hormone triiodothyronine and T4 is the thyroid hormone thyroxine.

The British Thyroid Foundation says that T3 and T4 are the two main hormones that your thyroid gland secretes. Together they affect and influence almost every cell in your body. Your thyroid usually produces more T4 hormone than T3, but T4 is converted to T3 when it reaches cells and tissues in your body. Therefore, T4 is the more important hormone to measure when testing for thyroid dysfunction. 4

Let’s look in more detail at what T3 does and why T4 is the more potent hormone.

What is T3?

Doctors from the Mayo Clinic say that triiodothyronine (T3) has 3 iodine molecules in its structure. This is secreted directly by the thyroid gland and is classed as the most powerful thyroid hormone. This is because it is more metabolically active when controlling your body’s metabolism, temperature, and digestive system. 5

What is Free T3 (FT3)?

Thyroid hormone binds to proteins in your body and any that isn’t is classed a free T3. The British Thyroid Foundation says that free T3 is the active part of triiodothyronine. The level of FT3 can help to diagnose hyperthyroidism and monitor replacement T3 therapy. 6

What is T3 Uptake?

Sometimes, you may hear doctors talking about T3 uptake when discussing thyroid testing. What is T3 (T3RU) uptake? The book Clinical Methods says that T3RU (T3 uptake) test measures the levels of proteins in the blood that carry thyroid hormone. 7 T3 uptake can help your doctor interpret the results of T3 and T4 blood tests. The T3RU test is hardly used these days because the TBG ( thyroxine-binding globulin ) and the free T4 blood tests are now available.

What is T4?

The thyroid gland also secretes T4, but in larger quantities than T3. Thyroxine (T4) has 4 iodine molecules attached to its molecular structure. When T4 gets into the cells of the body, it loses one molecule and becomes T3. Thyroid function tests that check both TSH and T4 levels are the most accurate ways to diagnose thyroid conditions. 8

What is Free T4 (FT4)?

Similar to free T3, free thyroxine (T4) levels are the unbound levels of T4 hormone (the active part of thyroxine). You have more free T4 (FT4) in your blood than FT3. High T4 levels or low T4 levels can help to accurately diagnose hyperthyroidism or hypothyroidism. The book Clinical Methods says that blood tests for both TSH and T4 help to accurately assess thyroid health. 7

The amount of free T4 helps doctors see how much thyroid gland hormone is available in your blood to meet your energy requirements.

Normal Levels of T3 and T4

If you show signs of abnormal thyroid function , doctors may arrange for a blood test to check FT4 levels and possibly free T3. This is usually done at the same time as a TSH blood test, or doctors may check T4 levels only if TSH blood test readings are abnormal.

Normal T3 levels (Normal Free T3 Levels and Total T3)

Dr. Jayita Poduval, who is an Ear, Nose, and Throat (EAT) specialist, says that the normal total T3 and free T3 ranges are as follows: 9

Total T3 (triiodothyronine) range:

• Children : 125 – 250 ng/dL
• Adults : 80 – 220 ng/dL

Normal free T3 (FT3) range:

• Adults : 260 – 460 pg/dL (4 – 7.4 pmol/L)

Normal T4 levels (Normal Free T4 Levels and Total T4)

Testing for normal levels of T4 thyroid hormone is a common lab test along with TSH to diagnose thyroid issues. Dr. Muhammad Bader Hammami on Medscape says that total T4 (TT4) range and free T4 (FT4) range are as follows: 10

Total T4 (TT4) range:

• Newborn babies up to 14 days old : 11.8 – 22.6 mcg/dL (152 – 292 nmol/L)
• Babies and older children : 6.4 – 13.3 mcg/dL (83 – 172 nmol/L)
• Adults : 5.4 – 11.5 mcg/dL (57 – 148 nmol/L)

Normal free T4 (FT4) range:

• Children and adolescents : 0.8 – 2 ng/dL (10 – 26 pmol/L)
• Adults : 0.7 – 1.8 ng/dL (9 – 23 pmol/L)
• Pregnant women : 0.5 – 1.0 ng/dL (6.5 – 13 pmol/L)

How TSH Affects T3 and T4 Levels

TSH, T4, and T3 are all connected with your thyroid function and TSH can affect thyroid hormone levels in your blood. TSH levels that are less than the normal range often indicate hyperthyroidism because your thyroid is overproducing T3 and T4. If your lab test results show high TSH levels , this can indicate that your thyroid is sluggish and there is not enough thyroid hormones.

To learn what your TSH levels mean, read my complete guide to TSH levels (including optimal thyroid levels) .

High T3 and T4

Having lab test readings that show high T3 and T4 can mean that you have hyperthyroidism. Doctors will usually test FT4 levels and may also run FT3 tests if your TSH readings are low.

High T3 Symptoms

Dr. Stephanie Lee on eMedicineHealth says that significantly higher than normal T3 can be a sign of severe hyperthyroidism. 11 According to the journal Clinical Endocrinology , Graves’ disease is a common cause of severe hyperthyroidism. This can cause symptoms like: 12 , 13

• Bulging eyes
• Thick red skin on the tops of your feet
• Inflamed eyes with a gritty feeling
• Increased sensitivity to light

High T4 symptoms

If your T4 test readings are too high, it can mean you have hyperthyroidism. According to Dr. Oliver Starr on Patient.info, classic signs of an overactive thyroid gland that secretes too much T4 hormone can include any of the following: 14

• Increased irritability and restlessness
• Poor sleeping habits and difficulty getting to sleep
• Runny stools because your digestive system is working too quickly
• Losing weight without trying
• Thinning hair
• Increased sweating
• Light menstrual periods
• Shortness of breath

Low T3 and T4

When levels of T3 and T4 fall below the normal range, you will probably show signs of hypothyroidism. Mild hypothyroidism can even occur if your TSH readings are within the normal range.

Low T4 Symptoms

Dr. Gabriel Bucurescu on Medscape says that classic symptoms of an underactive thyroid that doesn’t produce enough thyroid hormone can include: 15

• Feelings of weakness and fatigue
• Dry skin and hair
• Weight gain
• Problems with memory and concentration
• Tingling in the fingers or a feeling of ‘pins and needles’ in the feet
• Intolerance to the cold

Low T3 Symptoms

Usually, low T3 levels in a thyroid function test are matched by low T4 readings and elevated TSH levels. Therefore, T3 below the normal range usually means a person has hypothyroidism.

According to doctors from the American Association for Clinical Chemistry, it would be rare when blood tests show low T3 with low TSH and high T4. 16

How TSH is Connected with T3 and T4 Levels

Dr. Oliver Starr on Patient.info explains that all your thyroid hormones and TSH (thyroid-stimulating hormone) need to work in balance. This forms what doctors call a feedback loop where the levels of thyroid hormone in your blood signal to your brain to produce more or less TSH. 17

For example, if an overactive thyroid produces too much T4 or T3, the feedback loop to your brain signals to produce less TSH. The same is true if your thyroid isn’t working properly and produces too little hormone.

Doctors from the National Health Service explain the basic relationship between TSH and thyroid hormone levels: 18

• Hypothyroidism : TSH high, T4 low, and T3 low or normal
• Hyperthyroidism : TSH low, T4 high or normal, and T3 high or normal
• Subclinical thyroid disease : Levels of T4 and T3 are normal but TSH is either too high or too low
• Non-thyroidal illness : TSH low, T4 low or normal, and T3 low or normal

High (Elevated) TSH and Normal T4

Lab test results that show TSH levels greater than 4.0 mU/L and T4 within the normal range can indicate subclinical hypothyroidism.

According to the journal American Family Physician , subclinical hypothyroidism could show that person is at greater risk of developing an underactive thyroid disorder. This often happens in older women and there may be no visible symptoms. Doctors treat subclinical hypothyroidism on an individual basis as thyroid hormone replacement can lead to osteoporosis. 19

High TSH and Low T4

Blood test results that show TSH levels higher than the normal range and FT4 of less than 0.7 ng/dL mean that you have an underactive thyroid.

Dr. Laura J. Martin on WebMD says that some of the causes of hypothyroidism can include: 20

• Hashimoto’s thyroiditis (Hashimoto’s disease) which is an autoimmune disorder that attacks the thyroid gland
• Inflammation of the thyroid gland
• Radiation treatment for cancer
• A lack of iodine in the diet
• Pregnancy can also cause high TSH and low T4 readings

Low TSH and High T4

Test result reading of TSH of less than 0.4 mIU/L and FT4 more than 1.8 ng/dL means that your thyroid is overactive. Hyperthyroidism is less common that an underactive thyroid, however, similar to hypothyroidism, it affects women more than men.

Dr. Carol DerSarkissian on WebMD says that some conditions that are linked to hyperthyroidism can include: 21

• Antibodies in your blood that affect your thyroid (as in Graves’ disease)
• Noncancerous growths in your thyroid that cause it to swell and produce more T4
• An autoimmune condition
• Receiving too much thyroid replacement hormone

Normal TSH and Low T4

In some cases, TSH test results are within the normal range but low T4 results can occur. Dr. Louise Newson on Patient.info says that this can often happen in people who are chronically ill. The illness may affect a person’s metabolism which affects their thyroid hormone levels. This means that the pituitary gland is secreting TSH within the normal range and the thyroid is working properly. However, thyroid hormones in the body are lacking. 22

Also, if you have recently had treatment for hyperthyroidism, you could have normal TSH but low T4.

Treating Hypothyroidism with Replacement T4 and T3

Doctors treat the symptoms of hypothyroidism by prescribing oral thyroid hormone replacement therapy. Some treatments for an underactive thyroid involve prescribing T4 replacements like levothyroxine sodium (brand names: Levothroid, Levoxyl, Synthroid, or Tirosint). Other treatments involve a combination of T4 and T3 replacement therapy.

According to a study in the Journal of Clinical Endocrinology and Metabolism , there is a move towards using combined replacement of T4 and T3 therapies. Some doctors prefer this because the combined T4 and T3 thyroid treatments may have less impact on quality of life and treat hypothyroidism better. 23

Tests for Measuring T4 and T3

The British Thyroid Foundation says that testing for thyroid dysfunction can include one or more of the following tests: 6

• Testing to see if free thyroxine (FT4) is within the range of 0.7 – 1.8 ng/dL
• Free triiodothyronine (FT3) tests for the range of 260 – 480 pg/dL
• TSH and FT4 test
• Testing for thyroid antibodies to diagnose Graves’ disease or Hashimoto’s disease

Doctors recommend testing for T4 and T3 as part of a thyroid function test if you have any of the following symptoms:

• Fast or irregular heartbeat
• Thickening around the base of the neck
• High cholesterol
• Osteoporosis
• Feel unwell after having a baby

Read these related articles:

• How to Test Your Thyroid With a Thermometer
• TSH Levels: Normal, High, or Low (Including Optimal Thyroid Levels)
• 1 Minute At Home Thyroid Cancer Self-Test: This Can Save Your Life

Medical Sources:

• WebMD . Picture of the thyroid.
• ClevelandClinic . Thyroid blood tests.
• Front Endocrinol (Lausanne) . 2015; 6: 177.
• BTF-Thyroid . Your thyroid gland.
• MayoMedicalLaboratories . Test ID: T3
• BTF-Thyroid . Thyroid function tests.
• NCBI . Thyroid function tests.
• MedicineNet . Medical definition of thyroxine.
• Medscape . Triiodothyronine.
• Medscape . Thyroxine.
• eMedicineHealth . Hyperthyroidism.
• Clin Endocrinol (Oxf). 2010 Apr;72(4):551-7.
• MayoClinic . Graves’ disease.
• PatientInfo . Overactive thyroid gland.
• Medscape . Neurological manifestations of thyroid disease.
• LabTestsOnline . Free T3 and total T3.
• PatientInfo . Thyroid function tests.
• CamdenCCG . Abnormal thyroid function tests.
• Am Fam Physician . 2001 Nov 15;64(10):1717-1725.
• WebMD . Hypothyroidism.
• WebMD . Hyperthyroidism.
• J Clin Endocrinol Metab. 2012 Jul;97(7):2256-71.

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Thyroid Test Analyzer: Decode Your Results

This thyroid test analyzer will help you understand your TSH, T3, T4, and other thyroid function test results. Select a test and enter your lab value to learn more. “This tool is aimed to help you interpret your thyroid function test in order to clarify your diagnosis or track the progression of treatment. Please make sure you discuss with your doctor your concerns or questions.” – Ana Maria Kausel, MD .

Helpful Resources

Thyroid disease is common yet often misunderstood or overlooked. If your thyroid test results are outside of the optimal range—or if you’ve been diagnosed with hyperthyroidism , hypothyroidism , Graves’ disease, Hashimoto’s thyroiditis , or another thyroid-related condition—Verywell offers free resources to help you better understand and manage your condition. We want to help ensure you have productive and empowering discussions with your physicians.

Explore the following articles, tools, downloads, and communities to learn more:

• Read more about thyroid disease
• Read more about thyroid function tests and results
• Download the Thyroid Disease Doctor Discussion Guide
• Join the Real Life With Thyroid Disease Facebook Community

Frequently Asked Questions

What information do i need in order to get my thyroid test analysis.

All you need is the name of the test and the test value, as listed on your thyroid test results report that you receive from your doctor. You’ll need to provide both pieces of information to receive an analysis.

All test values should be numerical values—no need to add units, we’ll add those for you!

Which thyroid tests can be analyzed?

Our tool can analyze results from these common thyroid function tests:

• Thyroid stimulating hormone (TSH)
• Free thyroxine (Free T4)
• Free triiodothyronine (Free T3)
• Radioactive iodine uptake (RAIU) at 6 and 24 hours
• TRH stimulation test
• Thyroglobulin antibody
• Thyroid peroxidase antibodies (TPO)
• Thyroid Stimulating Immunoglobulins (TSI)
• Thyrotropin receptor antibodies (TRAb)

It will also analyze results from these thyroid tests that have been largely replaced but are still used in some practices:

• Total thyroxine (T4)
• Total triiodothyronine (T3)
• Free thyroxin index (FTI)
• T3 resin uptake (T3RU)
• Thyroid binding globulin (TBG), measured by electrophoresis and radioimmunoassay

You can analyze one test at a time. Remember, however, that many of these tests are related and the various thyroid hormones interact with each other and are affected by multiple factors . Your doctor is the best person to analyze your results as a whole—this tool is meant for informational purposes only.

Download this guide for a full overview of each thyroid function test, its optimal range, and what the results mean.

Download: Understanding the Various Thyroid Function Tests

Where can I find my thyroid test results or lab report?

In most cases, your test results will be ready a few days after your bloodwork or imaging test. You can obtain a copy from your doctor’s office, either at a visit or by calling in.

Your doctor will have the results even if the tests were performed outside of their office. They will likely call or schedule an appointment to review them with you. You can use this tool before or after your discussion to learn more about the different tests and results.

Some labs and offices also offer online patient portals where you can view your results without having to call in. Select the name of the test, as indicated on your report, and enter it into the analyzer, along with your listed numerical value, to receive an analysis.

Note that different laboratories may have different reference ranges for these tests. The reference ranges used in the analyzer are meant to represent typical ranges. If the ranges differ, you should refer to the specific ones provided by the laboratory in which the test was performed.

What information will I receive from the tool?

Once you enter your information, the thyroid function test analyzer will tell you if your result is low, optimal, or high and what that might mean. You’ll also learn a little bit about the test, why it’s done, and what it measures.

Patients with thyroid cancer, pregnancy or pituitary disorders must seek a specialist's care.

How were the results analyzed?

Your results analysis was completed by a board-certified physician. Optimal range values and interpretations are in line with leading thyroid authorities (although they sometimes slightly vary across laboratories).

Remember, however, that this analysis is for informational purposes only. You should use it as a starting point or to further understand what you have already discussed with your doctor. It is not a replacement for a professional medical visit.

Thyroid conditions and hormones are complicated and test results may be affected by multiple factors . Your doctor is the best person to take a holistic look at you, your medical history, and the relationships between your different thyroid hormones. They can provide you with the most customized, accurate interpretation and next steps to follow.

Who else can see my lab results or personal analysis?

We take online privacy very seriously, especially when it comes to individual and personalized health information. We do not track which lab tests you analyze and we do not store any lab values you enter. You are the only one who can see your analysis. Also, you will not be able to return to your results, so if you would like to save them it is best to print them.

Please see our Privacy Policy for more information.

Can this tool diagnose me with a thyroid condition?

This tool does not provide medical advice or diagnosis. It is intended for informational purposes only and is not a substitute for professional medical consultations, diagnosis, or treatment.

What should I do with the analysis?

You should use the analysis to empower yourself and learn more about your results, but not to diagnose yourself with a thyroid-related condition, such as hyperthyroidism , hypothyroidism , Graves’ disease, or Hashimoto’s thyroiditis . Proper diagnosis and treatment require a holistic look at your previous medical history, symptoms, lifestyle, and more. Your doctor is the best person to do this.

You can use this information to inspire questions or use it as a starting point for a conversation with your doctor at your next appointment. Asking the right questions can help you know what to expect.

Also, consider bringing along a doctor discussion guide for even more guidance—it lists common vocabulary terms your doctor may use and important questions about symptoms, causes, diagnosis, treatment, and living well with thyroid disease.

Download: Thyroid Disease Doctor Discussion Guide