Chasing ‘Ideal’ Thyroid Hormone Lab Test Results is The Road to Nowhere for Thyroid Patients

During the 1970s the shift to a lab-test-centric model began. This involved the increasing amount of focus by doctors on laboratory test results rather than symptom improvement in their patients. This was the start of conveyor-belt thyroid treatment using Levothyroxine (T4) medication. It was much easier and faster for doctors treating thyroid patients. Endocrinologists and doctors could get their thyroid patients in and out of their consulting rooms in record time. However, this approach, which still exists today, leaves many patients under-medicated or improperly treated.

Both doctors and patients are now highly focused on lab test results. In many cases, both groups (patients and doctors) are operating under the mistaken belief that by focusing mostly on trying to achieve some ‘ideal’ lab test results, the patients will fully recover. 

This blog post points out the huge flaws in this approach.

Note the focus of this blog post is on lab testing during thyroid treatment.  Lab test results are extremely valuable during the diagnosis stage, prior to a patient being given any thyroid hormone – there is no question of this.

What Usually Happens During Thyroid Treatment?

Most doctors use the TSH test to assess their patients’ thyroid medication dosage. The standard thyroid medication is Levothyroxine/Synthroid/T4. Some doctors also test Free T4 (FT4) and a few also test Free T3 (FT3). 

Most of these doctors are content that their patient is well treated on T4 medication if the patient’s TSH is in the reference range. Some prefer to see TSH low in the reference range. Most doctors get concerned if TSH is near zero. TSH has become the de facto way of assessing the T4 medication dosage. T4 has become the de facto treatment. 

As for patients, they too are interested in their thyroid lab test results. Some better-informed patients are hoping for an FT3 level that is between the middle and the top of the FT3 laboratory range. Some seem to be trying to achieve some ratio of Free T3 to Reverse T3 (FT3//rT3 ratio), that is if they can get rT3 tested. Most of the well-informed patients are still using T4 medication or natural desiccated thyroid medication (if they can get it).

Some History Prior to the 1970s.

Synthetic T4 (Synthroid, Levothyroxine) was first introduced in the 1950s. Current thyroid lab tests (TSH, and the other thyroid labs) were invented in the 1970s.

Before these events, all doctors had available was good clinical judgement, based on the symptoms and signs (body temperature, etc. and possibly basal metabolic rate) of the patient, and the option to use natural desiccated thyroid (NDT).

Previously, when doctors worked with a patient, they would assess many things and try to reach a judgement over whether the patient might have a thyroid problem or not. If low thyroid hormones were suspected, a trial of NDT would be started. If there were improvements in symptoms and signs, the NDT would be adjusted (titrated) to a higher or lower dose if needed. This titration process would continue based on the presenting symptoms and signs of the patient. This meant that the doctor would have to work with the patient and listen to what they were saying about how they were feeling in response to treatment. There were no laboratory tests to get in the way between the doctor and the patient in front of them. The improvement in the well-being of the thyroid patient was the primary goal prior to the 1970s.

This approach worked pretty well a lot of the time. It ought to have moved forward from there, taking advantage of modern lab testing (but not being a slave to it), and having all the other thyroid medications available. 

What Happened from the 1970s Onwards?

In the 1970s the TSH test became the standard way to assess whether thyroid treatment was working. Levothyroxine/Synthroid/T4 became the standard medication for treatment. Both of these required almost no effort on the part of the doctor or endocrinologist compared to what happened in the past. It vastly reduced the work of the physician. The reliance on the TSH test and the use of T4 medication also virtually guaranteed that no patient would ever be over-medicated. However, they were likely to be under-medicated! 

This sea-change was the beginning of conveyor-belt thyroid treatment, optimised for the doctor, and far less likely to result in over-medication of the patient. It was much more likely to result in the under-medication of the patient!

Unfortunately, it is a method that frequently results in improperly treated hypothyroidism. Patients are often under-medicated and do not have enough T3 thyroid hormone. It is a broken paradigm.

Why is this a broken paradigm?

I have written about this in many other blog posts, but here is a resume based on recent research:

  1. Research has shown that it is safe for TSH to be totally suppressed when on thyroid treatment, i.e. near zero. This is fine and it does not mean the patient is hyperthyroid if they show no symptoms or signs of hyperthyroidism. Many doctors believe that once TSH gets into the laboratory reference range that the patient must be properly treated. This leaves many thyroid patients under-medicated!

  2. TSH does not track symptom improvement. So, a doctor ought not to see a change in T4 medication and a lowering of TSH and assume that the patient is doing better. But we all know that many think just like this. See this blog post for more information on the symptoms of hypothyroidism:

  3. FT4 does not track symptom improvement either. A higher level of FT4 does not mean that the patient will be feeling better.

  4. Free T3 does track symptom improvement. However, FT3 is not the measure that most doctors focus on. Often FT3 is not tested and the T3 level is not considered to be important.

  5. The reference ranges for FT4 and FT3 are population ranges. These are far too wide to conclude anything about whether a patient is well-treated or not. Real individual reference ranges (which cannot be known before treatment) are much narrower than the large population ranges. Individual ranges of FT4 and FT3 required for a person to be well have been shown to be less than half as wide as the wide laboratory population ranges that most doctors are using.

  6. Reverse T3 (rT3) may or may not be an issue, and for sure there is no ideal FT3/rT3 ratio for all patients. Just as the lab ranges are wide population ranges, people all have their own individual requirements for their labs. No ratio or reference range can be applied to all people. Very high rT3 is usually an issue but that’s about all you can say about it in isolation. Symptoms and signs of the patient say more.

  7. T4 does not work for all patients. Some patients cannot get well using T4 medication.

  8. We also know that the thyroid gland itself is responsible for around 25% of our T3, mostly through conversion, so tissue damage through Hashimoto’s, or through the removal of the thyroid, loses a huge amount of ability to convert from T4 to T3. This can often not be compensated for with T4 alone. There is also a great variation in the amount of T3 produced by the thyroid gland itself, and in people who do not convert T4 to T3 very well the thyroid gland is able to make more of its own T3 thus compensating for this. So, in cases of Hashimoto’s or thyroidectomy the loss of T3 can be even more dramatic for some individuals who are more reliant on their thyroid gland for T3 production.

  9. Research has shown that the loss of conversion capability and of the thyroid gland in thyroidectomy patients, causes the loss of the ability to achieve a balance of thyroid hormones and good conversion rate (homeostatic balance).

  10. We also know from research that some people have genetic defects that reduce the capability to convert from T4 to T3 (DIO1 and DIO2 gene defects).

Moreover, we know from the experience of an immense body of thyroid patients that many of them need different medications to get well: T4, NDT, T4/T3, or in some cases T3-Only.  

Logic and patient experience also suggest that once a thyroid patient is on a combination of T4 & T3 treatments the laboratory reference ranges can break down. The ranges are based on people with no thyroid issues or those on T4 treatment. They are not based on those on combined T4/T3 or T3-Only. It is not reasonable to hold a thyroid patient’s T3 medication level down in order to satisfy the need to keep FT3 within the range if the patient has no indication at all of being over-medicated. On T3-Only in particular, the patient often has to have FT3 above the top of the range before they feel well (for good reasons I have explained in my books and on my blog).

So, the current paradigm of thyroid treatment is broken, and the research has shown this.

The Consequences of the Broken Paradigm.

This is the really sad aspect of all of this.

Thyroid patients are being left improperly treated in many cases. They are either on the wrong medication for them, or they are being left under-medicated.

Both doctors and thyroid patients are now incredibly focused on lab test results. This alone is liable to waste vast amounts of time, and not lead to good treatment and outcome. Both thyroid patients and doctors are chasing some ideal set of laboratory test results. We know from the research that it is virtually impossible to use just the lab test results to determine if someone is either on the right medication or the correct dosage of it.

The shift to this broken paradigm of lab-test-focused treatment and T4 medication has caused generations of doctors and patients to become fixated with lab test results. It has caused both doctors and patients to believe that these test results will reveal something amazing. It is sad because the lab test-focused approach will not work – the research has proven this.

What Ought to Happen?

Lab test results should only be used in a supportive role during treatment.

You do need to have the lab test results, but watching how they change in relation to each other and to symptoms and signs is the most important thing.

The medical history of the patient and their presenting symptoms and signs should always be centre stage.

The focus should be on improving how well the patient feels. Labs can give an indication if the treatment is working well. 

Here are two examples:

  1. For a thyroid patient on natural desiccated thyroid (NDT), if the NDT was increased and the patient felt they had more energy, and FT3 also increased, and TSH lowered and FT4 raised a little, this would indicate that the NDT was being absorbed. It would also suggest that the treatment was resulting in higher FT3, which we know tracks symptoms. Because the patient said they had more energy it would be clear that they were actually responding to treatment. This process of adjustment could continue until the patient felt well. Even if TSH went to zero it would not be a concern as long as the patient does not feel hyperthyroid, and FT3 does not go over the top of the reference range (there may be exceptions to this last point. When the level of T3 medication gets higher, I would argue that a little over the reference range is also ok). If treatment was done like this many more patients would get well.

  2. For a thyroid patient on T4 medication, or even NDT medication, if this dosage was adjusted and FT3 was mid-range, FT4 was mid-range, and TSH only 2.0, some doctors would say that the patient was properly treated, even if the patient continued to have serious symptoms. It is a common occurrence for doctors or endocrinologists to pronounce that the thyroid patient is adequately treated, and to suggest that something else must be causing the symptoms, e.g. Chronic Fatigue Syndrome (CFS). This ‘some other problem’ excuse is used far too often by doctors. What ought to occur is that the labs should not be used to determine if the medication is sufficient. The medication should be increased, even though the lab tests are in the middle of the range. On thyroid treatment, TSH can be suppressed, and many patients do better with high in the range FT3. But the main thing, in this case, is that the patient does not feel adequately treated. They still have symptoms. In many cases, T4 medication will not fix all the symptoms. A T4/T3 combination of some kind might be needed. In a small percentage of cases far more T3 may be needed. Unfortunately, in many cases, the thyroid medication is never increased to the right level and the option to switch medication type is simply never offered.

The clinical response of the patient to changes in treatment (the medication type or the dosage of it) should be paramount. Symptoms and signs should be at the forefront of treatment assessment.

Treatment should be patient-centric, not lab-test-centric once again. Just focusing on lab tests as the most significant thing and looking for some mythical good level is not what doctors or patients should be doing.

Laboratory tests should be used only to assess how the labs are changing in response to treatment and they should not be used to state whether the treatment is adequate or not.

The clinical presentation – the SYMPTOMS and the SIGNS are the most important things, with the labs being subservient to these. 

The change in the way thyroid treatment is managed that occurred in the 1970s has been the biggest step backward that we have ever seen with the treatment of this disease.

We need a change in both the way doctors think about thyroid treatment and the way the thyroid patients themselves think about thyroid treatment.

Doctors and thyroid patients are both too focused on chasing ‘ideal’ thyroid laboratory test results. This has been the road to nowhere for some time and it continues to lead there. 

The advent of thyroid lab tests for TSH, FT4 and FT3 ought to have made thyroid treatment far better and easier. However, in the process of using them, they have become the main focus and T4 medication has become the main treatment. This is where it has all gone wrong. 

Both groups of people (doctors and patients) have been mesmerised by what could be viewed as the ‘biggest confidence trick’ in the history of treating thyroid problems (a confidence trick that has been played on both patients and doctors).

I hope this was helpful. It was not intended to be depressing – simply eye-opening.

The majority of the information within this blog post is also contained and expanded upon in my book, The Thyroid Patient’s Manual.

Best wishes,


Paul Robinson

Paul Robinson is a British author and thyroid patient advocate. The focus of his books and work is on helping patients recover from hypothyroidism. Paul has accumulated a wealth of knowledge on thyroid and adrenal dysfunction and their treatment. His three books cover all of this.

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