There are several tests for your thyroid.
One of the most common tests your doctor will order is a “TSH reflex on abnormal to free T4” test.
In this article, I’ll help you to understand the test, how it works and what your results might mean.
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What is Thyroid Stimulating Hormone (TSH)?
Thyroid-stimulating hormone (otherwise known as TSH) is a hormone that comes from your pituitary gland and tells your thyroid to work. The fact is that your thyroid only works when it’s told to work, and it works more when you yell at it and less when you whisper to it.
The TSH can be a whisper or a yell, or somewhere in between. Depending on how high your TSH score is, that should reflect just how much your thyroid is going to work. Essentially, your pituitary is adjusting exactly how much thyroid hormone your thyroid is releasing.
Your TSH is also a backward indicator. If your thyroid is super underactive and not doing its job, then it will get yelled at — pushing your TSH scores higher and higher. If it’s working way too much, your TSH score will only go lower.
Key Insight: When your TSH works, it will urge your thyroid to create the hormone T4. That encompasses about 80-90% of the hormone that your thyroid makes in total.
What Is The TSH Reflex Test?
The TSH reflex test is first devised to see if your TSH is in the normal range. If your TSH is well beyond range, your thyroid may be overactive. If your score is way above range, then you may be struggling with an underactive thyroid (not always, in both cases, but maybe).
The reflex portion of the test means that if the TSH is abnormal, the lab will automatically measure the T4 and how much T4 is present. Why not measure it anyway? You can, but this is mostly a matter of both convenience and cost.
Key Insight: If your TSH is normal, the odds of the T4 being either way above or below range are minimal. It’s not irrational to avoid that second test if it may not be necessary.
If the TSH is high, will the T4 always be low? Not necessarily. We call that subclinical hypothyroidism — this is where the thyroid is getting yelled at, but it is continuing to work. That is very different from what we call overt hypothyroidism.
In cases of overt hypothyroidism, where the thyroid is essentially unable to work, then thyroid medication may be a good choice. That said, when it comes to subclinical hypothyroidism, then there’s not really a need for medication.
The thyroid may be at risk of slowing down, but it has not slowed down enough to warrant medication. The same dynamic is true on the other side of the equation.
If the TSH is below range, the T4 might be normal or it might be elevated. If the T4 is normal, we call that subclinical hyperthyroidism. This is where there is not an abundance of an excess hormone present — as opposed to overt hyperthyroidism where there is this abundance.
When Does TSH Reflex Testing Occur?
For adults, a TSH reflex test is good practice as a routine screen. The same as monitoring your blood sugar, cholesterol, or blood pressure, some folks are more at risk so it may help to keep an eye on this as part of a regular testing regimen.
As a generalization, those who have a family history of thyroid disease are going to be more at risk and benefit from routine screening. At the same time, women are also more at risk than men and adults are way more at risk than children.
There are also those who may be struggling with symptoms currently. This could include some of the more common hypothyroid symptoms like:
- Weight gain
- Hair loss
- Fatigue
- Depression
- Menstrual irregularities
- Constipation
Or, someone may have symptoms of hyperthyroidism which includes all of the above alongside a higher heart rate and increased palpitations.
Reading TSH Reflex Test Results
If you take a look at the handy chart above, you’ll find that most labs consider between 0.4 to 4.5 the low and the high end of the range for TSH.
This means that when the TSH is below that, one would reflex for measuring T4 and when it’s above one would do the same. Generally, subclinical hypothyroidism can include TSH scores between 4.5 and 10 (maybe 15 and sometimes 20).
When it is way above 20, that is almost always present with overt hypothyroidism. In those cases, it is then important what is causing it.
T4 helps to see how much hormone is coming out of the thyroid, but the autoimmune markers that we now need to test (like thyroid antibodies) help one know if there is an autoimmune disease present.
Key Insight: The most common cause of autoimmune disease in hypothyroidism is called Hashimoto’s disease, while the alternative present in cases of hyperthyroidism is called Graves’ disease.
How Important Is The TSH Reflex Test?
The most important thing to know from today’s discussion is that one can identify thyroid disease through blood tests. While it does take a doctor to know which tests to run and which will be the most insightful, it is possible.
Once something has been detected, though, what do you do next? My recommendation to you is to know that natural things are the mainstays of therapy, including:
- Diet
- Lifestyle
- Nutraceuticals
These things help in almost all cases. Thyroid medications are often not useful, not helpful and a bit too overused. Here’s a quick chart I put together to help you think through all of this:
The thing I want you to take away from today’s discussion is that a TSH reflex test is a valid screen, but it’s only the beginning of the story. When you work with the right healthcare professional, they can ensure you’re on the right route to recovery.
Have you been thinking about the state of your thyroid? I’d love for you to figure out which supplements would benefit you the most. You can click here and take this short quiz to find out how they can serve your thyroid the best.
P.S. Whenever you are ready, here is how I can help you now:
- Schedule a Thyroid Second Opinion with me, Dr. C, Click Here for Details
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Dr. Alan Glen Christianson (Dr. C) is a Naturopathic Endocrinologist and the author of The NY Times bestselling Hormone Healing Cookbook, The Metabolism Reset Diet, and The Thyroid Reset Diet.
Dr. C’s gift for figuring out what works has helped hundreds of thousands reverse thyroid disease, heal their adrenals, and lose weight naturally. Learn more about the surprising story that started his quest.
