Is there a "Best" Thyroid Test? A Simple Guide to Thyroid Testing

Is there a “Best” Thyroid Test? A Simple Guide to Thyroid Testing

Getting a complete thyroid hormone blood test is critical to understanding and evaluating your thyroid function. 

Complete thyroid testing includes so much more than the traditional TSH (which can be inaccurate in certain medical conditions). 

Without the right thyroid tests, you won't understand if your body is converting thyroid hormone appropriately or if your cells are taking up enough thyroid hormone. 

The lack of these functions results in hypothyroid like symptoms and specific changes to thyroid hormone that you can pick up with testing.

In this post, I am going to break down the most important thyroid lab tests, why they are important and how to interpret your results...


Thyroid Testing - What's Important and Why

There's a lot of confusion surrounding thyroid testing which can make things complicated if you are a patient suffering from hypothyroidism. 

In most cases, you are left to believe that the single best test for your thyroid is your TSH.

understanding thyroid lab tests

But is this actually true? Is it supported by scientific evidence?

The answer to that question is not really, and not in every situation.

There are actually many situations in which the TSH falls short and doesn't tell the "whole story" of what is going on in your body.

In some cases, patients understand that getting a full thyroid panel is important, but they still don't quite understand how their results fit into their current treatment regimen. 

And this is really important because certain thyroid medications influence your thyroid values in different ways. 

In some cases, these changes can be misleading to the inexperienced eye, unless you know what you are looking for. 

Complete thyroid blood tests image

But first let's start with the complete thyroid panel:

  • TSH
  • Free T3
  • Reverse T3
  • Free T4
  • Thyroid antibodies
  • Sex hormone binding globulin
  • Total T3

This list represents the entire and complete thyroid panel. 

This entire list isn't necessary each and every time you get your blood drawn, but this should always be drawn to completely and entirely evaluate your thyroid function.

This list should be drawn BEFORE you start taking medication and it should be drawn if you are worried that your symptoms are consistent with hypothyroidism.

Remember that while testing is critical to proper diagnosis and evaluation, accurate diagnosis and treatment is still required for optimal results. 

Taking this list to your doctor and demanding them to order these tests may not be helpful for the following reasons:

  • If you have to ask for these tests there is a high probability that your current provider may not treat you appropriately
  • Thyroid hormone replacement is nuanced and may require a combination of T4 + T3 for optimal results, this is contrary to the standard of care which is to provide patients with T4 only thyroid medication
  • Many physicians are set in their ways and unwilling to change their practice style regardless of data

Instead, a better option may be to find someone local to you who is experienced in dealing with thyroid issues and can help you further. 

We will touch on more of this later, but for now, let's jump into the evaluation of each of these lab tests: 

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TSH (Thyroid Stimulating Hormone)

The TSH level stands for thyroid stimulating hormone and it is secreted from your pituitary gland. 

Under normal physiologic function, TSH acts on the thyroid gland itself and stimulates thyroid hormone production.

High levels of indicate that your body may not be producing enough thyroid hormone.

This relationship can confuse patients because a high TSH means that you are likely hypothyroid.

TSH levels usually rise in response to a feedback loop in the body that exists to tell the brain when enough thyroid hormone is present. 

TSH and thyroid function in the body

If there are low blood levels of thyroid hormone your pituitary will sense this and it reacts by increasing TSH levels in an attempt to tell the thyroid gland to produce more thyroid hormone. 

This logic is then applied to thyroid hormone replacement. 

When doctors give patients thyroid hormone they then use the TSH to determine when the body has "enough" thyroid hormone in the body.

As you take thyroid hormone your TSH level will fall as the pituitary senses this thyroid hormone in the blood.

Eventually, your TSH level will drop and your doctor will say that you are "optimal", but is this really true?

In some cases, it may be, but in many cases, the TSH by itself isn't the best marker for assessing thyroid hormone status in the tissues. 

Some conditions may alter TSH levels and make using TSH inaccurate: 

  • Low T3 syndrome or euthyroid sick syndrome - This condition results in hypothyroid like symptoms but patients tend to have "normal" TSH levels with very low T3. 
  • Autoimmune thyroiditis syndromes - Conditions like Hashimoto's can alter peripheral conversion of thyroid hormone and result in reduced production of thyroid hormone from the gland. Many patients feel symptomatic with relatively preserved TSH levels. 
  • Inflammatory states that alter peripheral conversion of thyroid hormone - Inflammation in the body will result in reduced T4 to T3 conversion in peripheral tissues. The pituitary lacks deiodinase to create reverse T3 which can "trick" the pituitary into thinking more thyroid hormone is available. 
  • Leptin and insulin resistance - Hormone imbalances can alter thyroid hormone function at the cellular level. Even if circulating thyroid hormone levels in the blood are normal that doesn't mean that adequate cellular uptake is achieved. 

Beyond these conditions that may alter the effectiveness of the TSH as a marker of thyroid status, there are also some studies that refute this point. 

Some studies have shown that patients who take T4 only thyroid medication to lower their TSH to the "normal range" still exhibit lower T3:T4 levels compared to age-matched controls (1).

What's even more interesting about this comparison is that the patients taking thyroid hormone were likely to have more weight gain and were much more likely to be taking medication for depression, high cholesterol, and high blood pressure. 

Patients taking T4 to a "normal" TSH also consumed fewer calories per day and showed a slower metabolism compared to matched controls with the same TSH levels.

These findings match my observation in clinical practice as it relates to hypothyroid patients being treated with T4 thyroid medication. 

Most of my hypothyroid patients are consuming very few calories, have a big problem losing weight and are usually taking multiple medications.

Obviously our understanding of TSH as the "ultimate" thyroid lab test is limited, and as a result, it's a good idea to use other lab values in conjunction with the TSH for a better understanding of what is happening in each patient. 

While the TSH may not be the best test it still has value so don't discount it completely.

Normal & Optimal Ranges for TSH

So how can you use the TSH appropriately?

Monitoring your TSH while taking thyroid medication is very important, but it shouldn't be used by itself to alter your dosing.

Instead, it should be used with the other lab tests listed below.

In addition, what constitutes a "normal" range?

The optimal range for TSH, assuming you aren't taking thyroid medication is less than 2.0.

This assumes a standard range of 0.3 to 4.5 (or 5.0 as in the case below).

Generally, healthy patients exhibit a TSH of less than 2.0 (2) and patients with a TSH higher than 2.0 usually have hypothyroid symptoms. 

high TSH and hypothyroidism

The example above is a patient with obvious hypothyroidism because their TSH is outside even the "normal" range. 

In most cases, the TSH will likely fall between 2.0 and 4.5 which is probably the worst range to be in.

Patients in this range will be told that they are "normal", despite being symptomatic.

Many physicians will use the standard reference range of 0.3 to 4.5 instead of the optimal range of less than 2.0. 

When you are first evaluated (prior to taking thyroid medication) make sure you evaluate your TSH with this optimal range in mind. 

Free T3 (Triiodothyronine)

The next test we need to talk about is probably more important than the TSH and that is free T3. 

Free T3 is critical because it is THE active thyroid hormone in your body.

All of the positive actions we associate with proper thyroid function is from T3.

T3 directly activates nuclear receptors on each of your cells and changes genetic transcription which results in increased metabolism, increase hair growth, increased energy production, etc.

Free T3 represents the amount of free and active thyroid hormone floating around in your blood.

Thyroid conversion with leptin resistance

Some of this thyroid hormone is bound to a protein for transportation (this number is included in the total T3), but we are more interested in the part that is unbound and free.

By assessing your free T3 levels you some insight into how your body is metabolizing thyroid hormone.

In order for T3 to be created your body must cleave off an iodine moiety from T4 through enzymatic activity.

This process is known as thyroid conversion and it occurs in peripheral tissues, in the liver, and in the GI tract.

Conditions that alter your conversion of T4 to T3 may result in low T3 syndrome or euthyroid sick syndrome. 

In some states, your body may produce enough T4 which may result in "normal" TSH levels but inadequate T3 due to reduced peripheral conversion. 

This state presents with hypothyroid like symptoms and is frequently missed by many providers and patients.

Conditions that cause low T3 and reduced peripheral thyroid conversion: 

  • Systemic inflammation (high ESR/CRP or ferritin levels)
  • Chronic yo-yo dieting
  • Rapid weight loss (as in the HCG diet)
  • Certain medications: Beta blockers, antidepressants, anti-seizure medications
  • Chronic illness or recurrent chronic infection
  • Chronic stress
  • Hormone imbalances and hyperglucagonemia

Evaluating your free T3 is necessary to understand how your thyroid is functioning in the peripheral tissues. 

Free T3 normal & Optimal ranges

Like TSH, taking thyroid medication will certainly alter free T3 levels.

Doctors give patients T4 thyroid medication with the supposition that the body will take the T4 and turn it into T3.

It turns out that this can be evaluated by testing your T4 and T3 both before and after treatment.

If you see that T4 levels have increased, but T3 levels remain low (or slightly increased) you can infer there might be a problem with thyroid conversion.

Remember that T3 thyroid hormone is about 3-4x more powerful than T4 at lowering TSH (3) (but varies from patient to patient), so taking T3 thyroid containing medications will likely dramatically drop your TSH level.

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Despite this studies have shown (4) that when treating with T3 only thyroid medication (compared to T4) and even down to a "normal" TSH, patients taking T3 medications have more weight loss than those on T4 only thyroid medications. 

If you are taking T3 containing medication then evaluating your free T3 level becomes more difficult and less reliable. 

However, assuming you are not taking T3 thyroid containing medication, then the "optimal" range for free T3 should be in the upper 50% of the reference range.

Low free T3 levels, even with a normal TSH, generally present with hypothyroid like symptoms.


You can see an example above of a suboptimal free T3 level but still "normal". 

Reverse T3 (Reverse Triiodothyronine)

Reverse T3 is another VERY important thyroid lab test and it gives a lot of information. 

Reverse T3 is an inactive thyroid metabolite.

Remember when we discussed that your body can convert T4 into T3?

It can also turn that T4 into reverse T3 instead of T3 which inactivates the thyroid metabolite.

This system is meant to act as a brake and is a good thing in certain situations.

However, like many other processes in the body, this normal system can go haywire. 

States of chronic stress, illness, dieting, weight loss etc. can trigger the conversion of T4 to reverse T3 and act as a brake to your metabolism. 

Checking your reverse T3 can give further insight into the conversion process in your body. 

Patients with poor thyroid conversion will usually present with high reverse T3 levels, low to normal TSH levels and a low T3. 

Reverse T3 can also give insight into how much competition your body has for cellular binding between T3 and reverse T3. 

In most cases, you want this spectrum to be in favor of free T3 binding (so that you get the benefits of thyroid hormone). 

Patients with high reverse T3 will often present with weight gain, a very slow metabolism and other symptoms of hypothyroidism.

Reverse T3 normal & Optimal ranges

If you are taking T4 thyroid medication you will want your reverse T3 to be less than 15.0.

The standard reference range usually varies between 9.0 to 25.0


A reverse T3 greater than 15 with a lowish T3 is usually compatible with symptoms of hypothyroidism and a condition known as tissue level hypothyroidism (5).

This is another syndrome were TSH levels can falsely predict peripheral tissue levels of thyroid hormone.

In most cases, you will probably have to ask for the reverse T3 to be tested as this is not a standard thyroid test providers are used to ordering.

Remember to evaluate your reverse T3 in conjunction with both the TSH and free T3 levels.

Reverse T3 levels are closely associated with weight loss and metabolism: 

The more rapid you lose weight the higher your reverse T3 will be and the slower your metabolism will be. 

This usually occurs with extreme calorie restriction.

The example above is from a patient who just finished the HCG diet who presented with rapid weight gain and symptoms of hypothyroidism.

This high reverse T3 is likely a compensatory reaction from the dramatic drop in weight and meant to help lower her metabolism to "protect" the body from the rapid weight loss. 

Safe weight loss does not result in this type of rise in the reverse T3. 

Free T4 (Thyroxine)

Your free T4, while not the active thyroid hormone metabolite, still has value and is worth evaluating. 

Free T4 can give you insight into how your body is absorbing thyroid hormone.

In some cases, usually due to gastrointestinal issues, patients do not adequately absorb thyroid hormone.

This has given rise to newer thyroid medications with fewer inactive ingredients like Tirosint which can help in absorption.

By assessing free T4 levels before and after initiating thyroid hormone you can determine how well you are absorbing thyroid hormone. 

T4 levels also give insight into how well your body is converting thyroid hormone.

High levels of free T4 with low levels of T3 may indicate a conversion problem.

But be careful:

High or normal levels of T4 do not necessarily indicate that your body is utilizing thyroid hormone in peripheral tissues. 

Free T4 normal & Optimal ranges

Free T4 levels can change depending on the type of thyroid hormone you are taking.

Your free T4 level, like free T3, should be in the top 50% of the reference range - assuming you are NOT taking thyroid medication.

Your T4 levels will increase when taking T4 only thyroid medications like levothyroxine, Synthroid or Tirosint - but this isn't necessarily a good thing unless you are also converting this T4 to T3.

Conversely, your T4 levels may drop dramatically when taking NDT and/or T3 only thyroid hormone.

Your T4 level in these cases is usually not as important as your free T3/reverse T3 ratio, but it's still worth evaluating. 

low free t4

The example above is very common in patients with hypothyroidism who are not already taking thyroid medication. 

This TSH represents a "normal" level but certainly a "sub-optimal" level and most likely consistent with hypothyroidism. 

Thyroid Antibodies (TPOab & TGBab)

Checking your thyroid antibodies should also be a necessary part of a complete thyroid panel. 

This is important for several reasons:

#1. The presence of these antibodies indicates that a likely autoimmune and inflammatory component may be the underlying cause of your hypothyroidism. 

#2. Autoimmune thyroiditis is thought to be the #1 cause of hypothyroidism in the US. 

#3. The presence of antibodies indicates a condition which can be treated through lifestyle and dietary changes and alters treatment.

The presence of elevated antibodies (with hypothyroidism) may indicate an autoimmune attack on your thyroid gland. 

This is important because, if untreated, may result in thyroidal gland damage over the long term.

The conventional approach is to take a "wait and see" approach.

That basically means wait until the autoimmune process has caused enough damage to finally alter your TSH to a certain level as to require thyroid hormone replacement.

Does this sound like a good approach for patients?

Not really.

Instead, it presents an opportunity for significant change to your lifestyle which may (but not necessarily) help reduce the attack on your thyroid gland. 

It has been well established that various factors including environmental triggers (6), viral infections (7), and even stress can trigger, initiate and potentiate autoimmune diseases (8).

Doesn't it make sense, then, to try and reduce the impact that these factors have on your body?

Of course, it does. 

Which is why it is important to know if antibodies are elevated in your body!

Another important reason to identify if antibodies are present in your body is that your thyroid function tests may change over time due to this issue. 

Patients with autoimmune thyroiditis may experience episodic episodes of hyperthyroidism and hypothyroidism and flare-ups which can be confusing if the entire picture isn't clear.

TSH fluctuating over time with autoimmune thyroiditis

You can find more information about testing and treating elevated antibodies in this detailed post.

Thyroid antibody normal & Optimal ranges

Testing for thyroid antibodies is relatively easy:

Your antibody levels should be as close to zero as possible.

In most cases the reference range is accurate as in the case below:

Hashimotos thyroiditis with high TPO antibodies

The reference range indicates that normal antibody levels should be less than 6. 

This patient on the other hand obviously has elevated antibody levels with an actual level of 1317.

This represents an opportunity to make changes to try and lower or change this value.

Sex Hormone Binding Globulin (SHBG)

Sex hormone binding globulin is one of the few tools we have which can attempt to give insight into how your body is absorbing and utilizing thyroid hormone.

Sex hormone binding globulin is released from your liver in response to two hormones:

#1. Estrogen

#2. Thyroid hormone

Assuming estrogen levels are normal (and assuming you aren't taking OCP or estradiol) this test can help determine if your liver is assimilating and converting thyroid hormone in your liver. 

This information can then be used as a surrogate marker for other peripheral tissue levels of thyroid hormone.

It's not a perfect test, but it can give further insight into your thyroid function.

In women, an optimal sex hormone binding globulin is usually in the 70-80 nmol/L range.

In men, this number is usually in the 20-30 nmol/L range.

SHBG and hypothyroidism

In hypothyroid states (states where tissue levels of thyroid hormone are low) the SHBG will be low.

You can then track the SHBG, which should increase with thyroid hormone replacement, to help determine if your body is converting thyroid hormone appropriately.

Sex hormone binding globulin normal & Optimal ranges

Sex hormone binding globulin can only be used in certain instances. 

If you are taking oral contraceptives or oral estradiol then your sex hormone binding globulin will be artificially elevated and the absolute value of this test diminishes.

Likeweise, the SHBG can be used to determine if your thyroid dose is too high (again assuming estrogen levels are normal).

High SHBG levels may have consequences on other sex hormones in the body, which is one reason you don't necessarily want abnormally high SHBG levels in the body. 

SHBG should be part of the complete thyroid panel but its use is somewhat nuanced.

Final thoughts

Because of emerging trends in thyroid function and increased understanding of various clinical states that alter peripheral thyroid hormone levels and conversion it's becoming increasingly important for patients to have a complete thyroid hormone panel. 

Beyond obtaining these important tests it is also equally important (if not more important) to understand how these values change or alter treatment.

As a reminder, it's important to start with these tests to have a complete understanding of thyroid hormone PRIOR to initiating thyroid hormone replacement therapy.

The full thyroid hormone panel includes the following tests: TSH, free T3, free T4, reverse T3, thyroid antibodies, sex hormone binding globulin, and total T3. 

Now it's your turn:

Are you having trouble getting a complete thyroid panel?

Has it helped determine what is happening in your body with your thyroid?

Are you converting thyroid hormone appropriately?

Why or why not?

Leave your comment below!

References (Click to Expand)

is there a single best thyroid lab test?

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 70,000+ people have used them over the last 6 years. You can read more about my own personal health journey and why I am so passionate about what I do here.

P.S. Need more help? Check out my free thyroid downloads and resources.

56 thoughts on “Is there a “Best” Thyroid Test? A Simple Guide to Thyroid Testing”

  1. Dear Dr. Childs, thank you for this great blog, which my doctor’s office said (after I asked them to review it – you never know with the web, right?) is an “excellent resource”. Recently my doctor discovered an enlarged nodule on my thyroid. Long story made short, the fine needle biopsy result was “SUSPICIOUS FOR A HURTHLE CELL (ONCOCYTIC) NEOPLASM.”. I’m very concerned that the endocrinologist is going to recommend a lobectomy or thyroidectomy. I’ve been sicker than usual this winter and my TSH is 2.1, for the first time ever above 2. I’m feverishly analyzing my recent and historical lab results to find what has changed, in desperate hope that I’ll find an answer other than surgery. Here’s what I’ve found so far: I have consistently had a vitamin d deficiency, for the first time known there is bacteria in my urine, my iron level has increased, and glucose level is below the normal range. I noticed that when my glucose dips, my TSH rises – could there be a relationship? I’m in the Boston area so I am looking for doctors who practice functional medicine, while I go through the traditional consultations as well. My first endocrinologist appointment is tomorrow. If you see this, is there anything else I should ask, share or point out? Thank you again, Maureen

    • Hey Maureen,

      Generally thyroidectomy is recommended +/- RAI for malignancies of the thyroid gland (hurthle cell included).

      Your other issues are important, but may or may not be relevant to your current thyroid issue – only further evaluation will tell.

      • Dr. Childs thank you so much for posting this! Very informative! I do wish you could explain “thyroid antibodies” further. I know of TPO, TSI, and TRab. Are there others? Sometimes the same ones are called by different names. It seems that most doctors only know of TPO. It seems that some antibodies check for Hashimoto’s, some check for Grave’s, and some check for both. And I guess we may have antibodies for both hypo- and hyper- thyroid conditions. Any further explanations you could give to clarify these questions would be greatly appreciated! Thanks. Debbie Stevens.

        • Hey Debbie,

          I didn’t elaborate on the type of testing because, from my perspective and how I approach patient care, management doesn’t change dramatically based on the presence of certain antibodies but rather their presence period. More recently my practice has evolved to treat patients with or without autoimmune thyroiditis in a similar way, so the presence of these antibodies doesn’t change my management. Now, this logic most certainly does not apply to the average physician, but this article is more intended for patients than for providers and focuses more on diagnosis than management.

  2. FreeT4 and FreeT3 must be at 50% of the reference range whit no medication. OK, but this will change when taking medication?

    I am asking this because all over the INTERNET I see the recommendation that when on thyroid medication, the optimal FreeT3 value must be at least 75 % of the reference range.

    This confuse me, because before my thyroid treatment, my Free T3 was already at the 75% of the reference range, the problem and the reason of my diagnoses of hypothyroidism was my high TSH and low Free T4, and of course, the symptoms of low body temperature, fatigue, hair loss and joint pain on legs.

    A blog post about optimal values when on medication will be of great value.
    Thank you

    • Hey Lucas,

      The idea that free T3 and free T4 levels need to be in a certain place while taking medication is a construct created mostly by other patients. It stems from the fact that most hypothyroid patients are undertreated (which is mostly true) and from the idea that all problems in the body MUST be related to hypofunction of the thyroid gland (which isn’t true). This has lead to the mentality, in some patients, that any problem in a hypothyroid patient must be related to low thyroid function and therefore the answer to this dilemma is more thyroid hormone. As a result they suggest taking higher doses of thyroid hormone to get into this magical range where you will feel better.

      This doesn’t work in practice and just leaves patients manipulating thyroid dosing up and down trying to find these values while ignoring other more important factors. At some point I will elaborate on how I use these values to adjust dosing of thyroid hormone.

      • Dr. Westin, In your reply above you state, “The idea that free T3 and free T4 levels need to be in a certain place while taking medication is a construct created mostly by other patients. It stems from the fact that most hypothyroid patients are undertreated…” It has been my personal experience that doctors (at least in Indiana) base a patient’s treatment on plasma levels of Thyroid Hormones, even after beginning medication. These doctors might test for the pertinent Thyroid Hormones, such as TSH, Free T3, Free T4, Reverse T3, etc…, but do not base treatment upon the decrease, elimination, or improvement of symptoms. Instead, the doctor will increase or decrease a patient’s medication so that the patient’s Thyroid Hormones fit within a preconceived “optimal” level on a plasma blood test. As a personal example, doctors have decreased my Liothyronine (sustained release) medication because the TSH is too low, the Free T4 is too low, and the Free T3 is too high. Despite the expected return of my previously improved or eliminated symptoms, I have had quite a few doctors tell me that I am not, and in one case NEVER HAD Hypothyroidism, but am actually HypERthyroid, based solely upon the blood test results! In the doctor’s defense, however, they admit not being familiar or educated with using T3-only or Liothyronine Thyroid Hormone replacement. In summary, it would be exceedingly helpful for you to post information about how doctors should be evaluating a patient’s progress and how to accurately dose medication, if basing the dosage on a patient’s plasma levels. Thank you, Dr. Child’s!

        • Hi Alaina,

          Thanks for sharing your story! Many physicians equate true endogenous hyperthyroidism (with a suppressed TSH and high free T3) with iatrogenic suppression of the TSH with thyroid medication. But there is a big difference between suppressing the TSH with T4 medication vs T3 medication and the degree of suppression matters as well.

          I will plan to do a blog post on this in the future. Thanks for the input!

          • Dear Dr. Childs,

            Thank you for responding to my comment!

            I’ve been reading through your recent articles, and I am curious if you have written a blog post about Lab Testing for Thyroid Issues including what the optimal ranges should be for patients ON medication, typical patterns to be expected in lab testing when taking different thyroid medications, etc…?

            Thank you for all you do to help people suffering with thyroid issues!

          • Hi Alaina,

            I have not written an article on that exact topic but it is something I am considering for the future.

  3. Dr. Westin, perfect timing on this artice, I just seen my Nurse Practioner today that specializes in Functional Medicine-Hashimotos Thyroiditis, and she is ordering blood work for my complete thyroid panel, also nutritional deficiencies-Vit B-12, Vit D, my Adrenals, my cortisol levels, hemoglobin levels, thyroid antibodies, etc. I have a long list, and I will see her next month with the results. My primary Doctor placed me on Synthroid, and I was taking it at night, but I was told today by my Nurse Practioner to take first thing in the morning, and take the calcium at dinner time, and take the synthyroid after the blood work (Fasting). Dr. Westin, I appreciate your blog, and you have answered quite a few of my questions. Thank you for the article on how to restore the hair as well.

  4. Thank you so much for your help and assistance. My doctor told me the reason I am overweight was due to overeating not my being hypothyroid. I was always slender until i became hypothyroid. I plan on taking your hypo diet in the near future. Hopefully very near future. Thank you so much again.

  5. Hello

    I’ve been on NDT for four weeks and got retested yesterday . My TSH is now 4.5 (6.07 before treatment ) but my free T4 and T3 levels are now lower than before ( low end of normal) . I did not take the natural thyroid before the bloodwork ( last dose was 25hrs prior to testing). How can these results be interpreted? I’m feeling a bit better energy wise but still really suffering with bloating and weight issues ! How can i monitor dose adjustments?

    • Hey Sc,

      I can’t provide or interpret your lab tests but I would point out that without reverse T3 and other serum tests it will be hard to interpret those tests correctly.

    • Thank you for your reply . In your opinion when should I take NDT in relation to bloodwork? Should I take it the day of ? The evening prior?

  6. Not sure if I put my questions in the right place or not, but I would like to be notified of your posting of the answers to my questions. Thanks. Debbie Stevens.

  7. Dr. Childs, thanks so much for all the valuable information. Is there a process you recommend for locating the “right” medical provider?

    • Hey Josh,

      I tend to avoid making recommendations for providers because I practice quite differently than the majority of providers out there. If I make a recommended and you go to that provider then you may feel unsatisfied when they don’t treat you appropriately or the way you see on my blog. If you can find someone who discusses the same concepts as me in videos/blog posts, has case studies showing how they practice, etc. then that would be a good place to start.

  8. Hey Dr. Childs,
    My doctor ran all the tests you recommended through Lab Corp. My problem is that Lab Corp uses different values than what your article uses and I can’t interpret my results based on your values. Can you help me?

    For example my:
    Thyroid Peroxidase (TPO) Ab 3.0 (0-34) IU/mL
    Free T4 0.75 (0.62-1.23ng/dl)
    Triiodothyronine (T3) 177 (71-180ng/dl)
    TSH 0.68 (0.34-5.60 uIU/mL)

    Thank you.

  9. I forgot to add that at the time of this blood work I was already taking WP Thyroid at 3/4 grain. Previous blood work showed elevated thyroid anti-bodies.

    Thank you!

  10. Can you please tell me if all over itching is a symptom of Hashimotos and or thyroid issues? It started two years ago and I have been taking an antihistamine daily. Pretty much kept. me from itching. Recently I have been under a great deal of stress and the itching is out of control. Any info you can offer is greatly appreciated. The itching started 9 mos before the Hashi’s diagnosis.

    • Dear Roxanna,

      It is possible for the itching to be related to allergies, or estrogen dominance. Have you had blood or salivary testing done to check your estrogen levels? It is common in patients with thyroid issues, especially hypothyroidism, to have issues with the liver having difficulty excreting excess estrogen, which can lead to allergy symptoms, itching, hives, and more. If you research Estrogen, Estrogen Dominance, and allergies, you will find lots of information online. I hope this helps!

  11. Dr. Childs,
    I am hypothyroid (recently diagnosed after suspecting I was for the past 4-5 years). I was put on 25 mcg of Synthroid 6 weeks ago and when I went back for labs, I asked for the additional tests you suggest on your site. My antibodies were normal, my leptin seems normal at 11.3 and they did A1C, which I think is okay at 5.2. I am confused about my thyroid function and if my conversion is okay or if I need to look at that. My appointment today reviewed the recent labs and dr increased my synthroid to 70-75 mcg.

    April, 2017 June, 2017 (6 weeks of 25 mcg of synthroid)
    TSH 3.00 4.21
    Free T3 3.70 3.50
    Free T4 .73 .80
    Rev T3 N/A 11.7

    I wondered if I should be on T3 medication vs Synthroid and if my labs show I’m converting properly. Any thoughts?

    Thanks for your time.

    • Hi Mary,

      The decision to add T3 depends on multiple factors but, most importantly, should be made in the setting of your symptoms and not lab tests in isolation.

      • Thanks for the reply.

        I failed to include my blood pressure, which had been pretty normal (147/78), was 147/92 after 6 weeks on Synthroid. I am 45 years old. I just read that T4 medications can sometimes raise your blood pressure. I will monitor it over the next few weeks. There are very few local doctors in my area that have a very limited understanding of what you relay on your site so I’m trying to educate myself as much as I can. The nurse practitioner helping my doctor told me she’s never ordered a Leptin lab test.

  12. Dr Childs

    I was determined to have Hashimotos my sex binding hormone and my thyroid antibodies are off the charts high 200 range.. ( what should be done to treat these ranges )

    I am on synthoid for my TSH which was originally at 5.4 when I was on 50 mcg my dr increased me to 75 mcg and my TSH decreased to 3.4.. I have had weight gain over the last year and half..

    Question I have is how do you treat the high levels of sex binding hormone and high thyroid antibodies?

  13. Dr. Child’s,

    I was diagnosed hypothyroid approximately ten years ago. I am a 56 year old male. I have been on .112mcg of levothyroxine. Since being diagnosed and medicated I have not seen any difference in symptoms (dry skin, constipation, sluggishness, etc…) I just came back from my annual physical today and the doctor said that my thyroid function is great. I had asked for a full thyroid panel, but in reviewing the blood test results I found that they only did a TSH, which came in at 2.750. My questions are as follows…

    1. What range TSH would be optimal under medication? I am finding various information on the internet.

    2. What would be the best way to proceed under the circumstances?

    3. Should I call back the doctor and ask for a full TSH panel?

    4. What would a full panel under my circumstances include?

    5. If my hypothyroidism had been medicated correctly, would I seeing my symptoms disappear?

    6. Could I be facing something greater that is currently undiagnosed?

    7. Do I need to see a hypothyroid specialist?

    8. Is there anything else I should know or ask?

    Thank you for your time, expertise, and consideration!


  14. Dear Dr. Childs,
    I have Hashimoto’s Disease. My doctor treats me with levothyroxine 25MG. When I try to take 50MG, ( which my doctor suggested )my symptoms become worse. Yet 25MG doesn’t make me feel better. After expressing my concerns about my T3 levels, I asked my doctor to run a full panel thyroid test and his response was this :
    In order to suspect an issue with the conversion from T4 to T3 (which is usually congenital) you Free T4 needs to be High with Abnormal TSH.

    There is no indication to check Free T3 as usually, it is not reliable. I would just recommend slow titration of Levoxyl 25 mcg and see how you are feeling.

    You still have a subclinical level of Underactive thyroid and it is safe to titrate slow.
    If he’s not even willing to do the tests, how will I ever know if this is the best treatment for me?

    This is my free T4 unmedicated :

    0.80 ng/dL 0.76-1.46 completed N 03/13/2018

    And my TSH 3rd Generation unmedicated

    6.350 u[iU]/mL 0.360-3.700 completed H 03/13/2018

    This is all I have for test results. I’m back on 25 MG of Levothyroxine. My fatigue is crazy. My muscles and joints feel like I’m 100 years old. I’ve been averaging 10 lbs a year weight gain, even though I follow a very strict diet of whole healthy foods. I’m depressed. I thought by seeking out an endocrinologist after all these years of trying to find answers through my GP that I would finally be on the right track. Now I’m not so sure though.

    Id really love to hear from you.


  15. Hello Dr. Childs,
    I have found your article very interesting and helpful. I would like to know how I can find a doctor in my area that will order these tests as well as treat me based on the results. What is the best way to go about this?
    Thank you,

  16. Hello, Dr. Childs first I would like to say thanks for posting this valuable information. I was recently diagnosed with Papillary thyroid cancer stage 1.I had a total thyroid to you on April 6.I currently taking Synthroid 125mg. I was wondering if there is any natural medication I could take and what vitamins are good for me.

  17. Hello Dr. Wesley, my doctor claims that a very low TSH (0.006) is not good. He says that chronically low TSH can lead to osteoporosis and cause congestive heart failure. I am a petite female and have been all my life, which predisposes me to osteoporosis later in life as he explains. Therefore, a very low TSH is especially not good for me. However, despite taking thyroid hormones I still have hypothyroid symptoms and would like to increase my current dosage. What should I do?

  18. I am hypothyroid and have been taking levothyroxine for approximately 15 years on the same dose of 50 mcg. Over the last 5 years, my TSH levels have gone from the low 2’s where it was for years on the chart to suddenly climbing up. Most recently my TSH was 4.320 uIU/ml. My doctor says I fall within the normal range so things are fine, however, shouldn’t it be lower since I am taking levothyroxine? My symptoms over the last 1.5 years have been very similar to when I was first diagnosed (dry hair, hair loss, irregular periods/spotting, fatigue) but the doctor says most likely perimenopause symptoms. Thanks in advance for any thoughts on this.

  19. Dr. Childs

    I just came across your blog because I have been having in my opinion, severe symptoms. Overly tired…so tired I don’t even want to focus to type this comment. I just want to go back to bed, skin and also weight gain that just doesn’t seem to be explained any other way than my thyroid. I have called my doctor and have an appointment set up for Friday. Here is some info I received from previous panels and then one that was taken in the winter.

    Before heading to my appointment I was hoping you could steer me in the right direction on how to handle my conversation with my doctor.

    2016 panel
    TSH. 2.15
    T4. 5.3
    T3. 28

    This past winter appt…
    TSH 3.52
    Free T4. .72

    Thank for your time.

  20. I have Hashimoto’s and am on Levothyroxine and am finally feeling good. I’ve revamped my diet and started light exercise and am no longer falling asleep all day long at work. However, my doctor just checked my TSH and it came back at 0.12 so she wants to lower my dosage. Is that too low? I’m scared that I’m finally feeling well and that lowering my medication is going to bring back all my symptoms again. What are your thoughts?

  21. Hi Dr. Childs,

    Thank you for your helpful blog! I have been treated for hypothyroidism for 10 years. Different doctors have had different opinions of whether a suppressed TSH is acceptable if taking concomitant T4 and T3 (Naturethroid and Cytomel). My current doctor believes that the risk of bone and heart issues is too great and is titrating my T3 down despite my hypothyroid symptoms. Example labs:

    TSH – 0.01 (0.450-4.5 ulU/mL)
    Free T3 – 2.7 (2.0-4.4 pg/ml )
    T4, Free – 1.1 (0.82-1.77 ng/DL)
    Reverse T3, Serum – 16 (9.2-24.1ng/dL)

    What is your opinion of an artificially suppressed TSH?

    Thank you, in advance!

  22. Hello Dr. Childs,

    I recently had labs done to check thyroid function after a lump near my thyroid was discovered. When I received the results, the tests done were only T4, Free T4, T3 uptake and TSH. Shouldn’t Free T3 always be run when checking thyroid function? Also, what exactly is T3 uptake in relation to the other tests?

    Thanks so much for your help!

    • Hi Erin,

      In my opinion, yes free T3 and total T3 should be checked, but many other physicians don’t necessarily share that opinion.

  23. I have been struggling with hypothyroidism for 25 years and have been taking Synthroid for as many years. So many adjustments to my medication. About a year ago, I began doing research and had felt like my primary physician has just kept prescribing without any true interest in me. I have now been going to an Endocrinologist. Currently, my TSH is low and I have moved from Synthroid 125 mcg to 100 mcg. I just don’t’ feel as if doctors are open to discussion regarding medications other than Synthroid and bloodwork other than TSH panel. This has been a very frustrating journey. I struggle with fatigue, moodiness, weight gain, etc. All the classic symptoms. I could go on and on but would appreciate a few words of encouragement. Thank you.

  24. Hi,

    I was diagnosed Adrenal Fatigue in 2010 and 8yrs later I have been improving BUT now thyroid issues. Over the years my TSH, FT3, FT4 was .746; 2.4; 1.31 (2014) 1.23; 2.6; 1.3 (2015) 1.83; 2.8; 0.73 (Dec 2016) [began taking NatureThroid>>> 1.15; 2.9; 0.87 ( Mar 2017).716; 2.8; 0.78 (Sept 2017)0.665; 2.8; 0.74 (May 2018). I asked my doctor to up my current NatureThroid from 32.5mg to a full grain but she responded that I am already “suppressed” and she’s concerned about osteoperosis? The last 2 weeks I’ve taken two 32.5mg and feel better but wonder if my numbers are going in the “right direction” since beginning NatureThroid. I see you’ve recommended RT3, Free T3/T4, Thyroid Antibody and Hormone Globulin test with the caveat to take these prior to starting treatment. Should I stop treatment for a specific time period and then get the tests done OR can I take tests now and deduct a path forward still yet?

  25. Dr. Childs, I really appreciate what you are doing for the community by providing detailed functional medicine approach for Thyroid and autoimmune conditions. I would like to order some of your supplements but I am not sure what I need and how much I need based on my labs and medication. I know you can not diagnosis, interpret, or provide medical advice. I am just trying to figure out what supplements to order and start taking. 5 years ago I was prescribed Tirosint 25 mcg initially and then increased to 50mcg. I have been taking this on and off for 5 years. I feel better when I take the Tirosint and my TSH drops from 5.0 to around 1.2-1.4 but I continue to have hair loss, dry skin, and other symptoms. I recently stopped the Tirosint for 3 months and here are my most recent lab results off the Tirosint:
    TSH: 4.95
    Free T4: 1.2
    Free T3: 2.4
    Reverse T3: 16
    TPO Ab: <1

    Just 14 months prior to these labs I was taking Tirosint 50mcg and my labs were:
    TSH 1.4
    TPO AB: 11 IU/ml
    Free T4: 1.51
    Free T3: 2.6
    Total T3: 94
    Ferritin: 27

    I also was recently diagnosed with Sjogren's Syndrome and Fibromyalgia, which I believe contributes to my over inflammatory state. I have noticed when I am on the Tirosint my TSH drops to around 1.5 but my Free T3 is always around 2.5. I am losing hair and feel very tired and continue to have symptoms. The only thing that improves on the Tirosint is I have less depression symptoms and a little more mental clarity when I am on it. I think based on all your articles I need to raise my Free T3 and lower my Reverse T3. I would like do this with diet, supplements and lifestyle changes. I am not sure if I should stay on the Tirosint 50mcg daily-now that found you and your amazing website 3 days ago I am second guessing everything. I don't not want to drive my T4 level up if this is not what my body needs. If I start one of your supplements to naturally improve my T3 should I stay on the Tirosint or try NDT medication? or lower Tirosint and add Cytomel? I am a Physician's Assistant x 19 years but very dissatisfied with what our western medical system has to offer for solutions. Absolutely no thought goes into the whole picture and the focus is on lab values and lowering TSH. I have lost faith in our medical system. They never recommend supplements or alternative therapies.

    • Hi Seema,

      I recommend that you stay on whatever medication you are taking and only make changes after 6-8 weeks and only in necessary. The supplements were designed to be taken with your thyroid medication (not in place of them).

      I hope this helps!

  26. Hi Dr Childs,

    I have a reverse t3 of 16.8 ng/dl. I am wondering if this is normal? I haven’t done the t3 ratio but I am wondering if 16.8 is normal?

  27. Hi Dr. Childs,
    In 2015 I had radiation therapy to my neck for larynx cancer. The late effect showed up a year later with a TSH of 5.04. I was put on Levothyroxine 25 mcg. 6 months later, TSH was 6. the next 6 month reading 4.5. I told my Dr that I would like to have an optimal reading like I had before the radiation which was 1.0 because my cycling performance significantly dropped. I also felt tired. My performance went from being up front and hanging in on hill climbs to being dropped on hills and struggling to keep up and dropping 1 mph average speed. so I was put on 75mcg. I don’t see improvement and asked for a full panel and was met with resistance. TSH 4.2 as of now.
    Should I in combination with the Levo try a low dose (5mcg) liothyronine? I don’t think he would comply, I am getting disgusted.

    • Hi Sal,

      It’s best to use your thyroid lab (including free T3 and free T4) tests to help guide your therapy with T4 and/or T3 medication. You will find that most conventional doctors are fine with only using the TSH but this method of treatment leads to serious quality of life issues in the patient. Despite this, doctors are still hesitant to treat any differently. If you can’t get anywhere with your current doctor then it may be better to seek out a second opinion.

  28. Dr. Childs,
    Simply: What if you have been taking Levothyroxine for 2+ years and find that the thyroid panel was NEVER done for “baseline” results? A full panel was done this past January – after medication dosages had been changed – up and down – numerous times during the past 2 years. Currently, I have a Free T3:Reverse T3 ration of 0.11. I have received a referral to a endocrinologist – how do I proceed?

    • Hi Karen,

      You don’t need the baseline set of labs, it’s just really helpful if you happen to have them. I would say most people don’t have a baseline set of healthy labs because they never go to the doctor when they are healthy. In terms of getting help from an endocrinologist, you probably won’t have much luck because they will likely treat you the exact same way as your PCP. Many people think they are getting better care switching to an endo and the opposite is actually true.

      You can find more information on how to find a thyroid doctor here:

  29. Hello Dr. Childs,

    Today I received the result of my Lab test.

    TSH (0.49 – 4.67) 0.00-
    FT3 (1.64 – 3.45) 3.15
    fT4 (0.71 – 1.85) 1.01

    and I am taking 10mg carbimazole every day.
    I hope you can help me, what should I do to have a normal TSH?

  30. My results:
    T4 TOTAL 6.50 ug/dL
    3.20 – 12.60 ug/dL
    T3 UPTAKE 30.00 %
    22.50 – 37.00 %
    TSH 0.64 uIU/mL
    0.35 – 5.50 uIU/mL
    1.05 – 4.50

    Having hair loss, tired etc. what should I ask my doctor?

  31. I am having a very difficult time finding a doctor who will do the complete thyroid testing. I have hypothyroidism and Hashimotos and I am currently on Tirosint. Any recommendations?


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