Top 5 Thyroid Testing Interpretation Tips for Practitioners

Thyroid testing can be a lot more straightforward to interpret than you may think. I know it’s easy for me to say that having worked with pathology testing for a long time. But really, when I am interpreting thyroid test results, I try to keep in mind a few key tips that help me to figure out what may be going on pretty quickly.

The key is knowing what to look for and knowing what looks right and what looks a little suss.

My Top Tips for Interpreting Thyroid Testing

Remember That TSH is a Balancer

(Thyroid Stimulating Hormone) TSH is usually the first thyroid biomarker that is tested, and there is a good reason for this.

It is the ultimate balancer in terms of keeping thyroid hormones, thyroxine (T4) and triiodothyronine (T3) in check.

It’s paramount that adequate levels of these two hormones are available in order to target tissues in the body.

TSH is constantly providing a balance between too much thyroid hormone and not enough. So this marker can change very quickly. This is important to keep in mind when reviewing results. If you see a TSH level that is creeping toward the high side or low side of the reference range, it’s a good idea to ask yourself, could there be something in the patient’s lifestyle that is transiently affecting results?

Things like chronic stress and nutrient deficiencies can certainly influence this. A variation in normal subclinical TSH values does not automatically mean that your patient is on their way to hypothyroidism.

However if you see stark decreases or increases in TSH levels that are close to or outside the reference range, then clearly the balancing act is failing. Something has indeed, gone wrong and requires further investigation.

Remember, when TSH is high, that must mean that thyroid hormones are low. If TSH is low, that must mean thyroid hormones are high.

Antibodies Can Elevate in Other Autoimmune Conditions

The antibodies that are often tested to assess the health of the thyroid are:

Thyroid peroxidase Antibodies (TPOAb)
Thyroglobulin Antibodies (TGAb)
Thyroid Receptor Antibodies (TRAb)

Each of these can tell us about thyroid autoimmune conditions that may be present. But something that many practitioners don’t realise, is that these antibodies can elevate when there are other autoimmune conditions present. Such as Rheumatoid arthritis and Lupus.

This is particularly important to realise, if you see elevated antibodies but all other thyroid hormones are within healthy ranges. When you see this, look to the rest of the body systems for signs of other autoimmune conditions.

Conversion is Key

Small amounts of T3 are produced directly but the majority is converted from T4. So when reviewing results, you want to look at the ratio of T4 to T3.

If you see high T4 but low T3, then you know there is a conversion problem. This will likely be resulting in the production of Reverse T3 (rT3) and will induce hypothyroid like symptoms.

But the problem may be as simple as not having the right nutrients to support conversion. It could be because of chronic infection or chronic high grade stress. These issues can all inhibit production of T3 and favour the production of rT3.

So taking note as conversion is key.

Reverse T3 - The Evil Twin?

I like to think of rT3 as the evil twin of T3. It’s not really evil. It is actually serving an important purpose. But it’s just easier to remember it this way.

T3 is a stimulator. It is a potent hormone that helps drive so many bodily processes. RT3 is its exact opposite. It is a depressor. It slows bodily processes down and makes them more snoozy. It usually does this in response to significant external conditions and the reason it does this is to support life.

When a person is exposed to toxic elements in their environment and they absorb these elements; The thyroid is usually the first to be susceptible to toxicity.

As a result, rT3 production is preferable to T3 because the rT3 can slow down the spread of toxicity and try to minimize damage caused. If you think of rT3 in this way it is easy to see why it will elevate. When there are severe infections in a patient, it makes sense to slow down bodily processes to inhibit the spread of infection. When there is chronic stress it makes sense that the body would want to slow down to try to recuperate from ongoing stressors.

RT3 induces hypothyroid like symptoms, not because it is evil/a disease state. But because these symptoms are a result of metabolism slowing down to combat a specific condition.

So when I see low T3 and elevated rT3, I ask myself, What condition does this person have that requires them to slow down? What is rT3 protecting them from?

Thyroid Cancer & Antibodies

It’s important to remember that the marker Thyroglobulin antibody is not just for assessing possible presence of thyroid autoimmunity. It is actually routinely used in the assessment of thyroid cancer and thyroid cancer treatment.

Thyroglobulin is usually tested as an indicator for thyroid cancer. Elevated levels are an indicator. But sometimes a patient’s immune system can produce thyroglobulin antibodies that actually destroy excess thyroglobulin. This can lead to false negatives during cancer treatment. This can lead an oncologist to believe that cancer is in remission when actually it is just the antibodies destroying excess thyroglobulin.

So indirectly, increased thyroglobulin antibodies can be an indicator that cancer is not in remission but that mutated thyrocytes are producing too much thyroglobulin and the immune system is responding to that.

So when you see elevated thyroglobulin antibody levels. It could mean that there is hashimoto’s thyroiditis (when TPO Ab levels are elevated alongside), sometimes it can mean Graves disease (often when TRAb levels are elevated alongside). But sometimes it can mean that thyroid cancer is present.

If you enjoyed this article and would like to learn more about Thyroid Testing, Our Foundations of Thyroid Testing Course may be just what you need.

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How to better understand TSH, T3 and T4 testing and get to know subclinical reference ranges and clinical findings
The various forms of antibody testing. What they mean, how to interpret results and how to approach treatment
You also get to learn all about rT3 from its use in the placenta of unborn babies to adults
You’ll learn about cofactor nutrients, specialist conditions and testing and how they can affect thyroid test results
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