Thyroid Thursday Episode 58: Why Don’t Doctors Run T3?
Hey everybody, it’s Dr. Eric Balcavage, and we’re back for another addition of Thyroid Thursday, and today, we want to answer a question that many of my patients have, and that is, why do doctors not want to run T3 or free T3?
And the answer for this is, most conventional medical doctors and endocrinologists, are taught that T3 isn’t that valuable in hypothyroid cases. Matter of fact, the American Thyroid Association guidelines say that, “… T3 is rarely helpful in a hypothyroid patient since it’s the last test to become abnormal.” TSH and T4 will become abnormal before T3 will, so doctors just don’t run it. They don’t see a value in it. Most times, they’re looking to give you a T4 support and they’re looking for TSH and T4 values to normalize, so looking at a T3 really isn’t that important to them.
Why is it that T3 is the last marker to become abnormal?
One of the answers is that the biology of the body actually defends serum T3 to maintain a normal lab level. In most situations, T3 doesn’t really leave the lab range. Now lab ranges are a bit broader range than functional ranges. Functional ranges which we use in functional medicine or integrative medicine are the optimal ranges for health. We use this narrower, healthy range and the functional range is really the range that the body works best in. Lab ranges are just a broader range. T3 and free T3 rarely ever leave these ranges because the body fights to defend T3 within that range.
Unfortunately, sometimes that’s at the detriment to your cells. The T3 in your serum doesn’t necessarily equal the amount of T3 that’s in your cells. T3 can be normal in the serum, but it can be deficient in the cells. T3 may be out of the functional range, but most times, it stays within that lab range.
Is T3 still an important test to run?
In functional medicine, it is still really important to run T3 because if it is high or low, outside the lab range or the functional range, we want to know that so we can understand why that’s happening, and understand how that is impacting our patients. We can also use T3 and free T3 in conjunction with something called reverse T3 to find out what’s happening at the cellular level with something called the deiodinase enzymes. Now I’ve talked about Deiodinase enzymes on other videos. The deiodinase enzymes are the enzymes that convert T4 to either T3 or reverse T3 and T3 to T2. It is really important to understand what’s happening to the T4 that your doctor puts into your system.
If we just look at T4 and TSH, we don’t know if that T4 is being converted efficiently in our peripheral cells to active T3 inside the cells or is it converting to reverse T3. So it becomes really important. If you get our T3 tests done we can compare it to reverse T3. We use T3/rT3 or fT3/rT3 ratio to evaluate deiodinase activity. If T3 divided by reverse T3 is less than 10, then we know you’re making more reverse T3 in relationship to T3. That means cells are increasing their deiodinase-3 to get rid of T3, and there is less T3 getting to the nucleus to stimulate your metabolism. If we take free T3 and divide it by reverse T3, and that number is less than 0.2, again that indicates that you probably have more deactivation of your T4 to this inactive hormone, reverse T3.
It is really important in functional medicine to understand what’s happening at the cellular level because thyroid physiology is really defined by what’s happening at the cellular level. Your symptoms, your hypothyroid symptoms, your dry skin, your thinning hair, your tiredness, your fatigue, is really the result of how much T3 is getting into your peripheral tissues. Most of the conversion of T4 to T3 for the cells of your body occurs in the peripheral cells. Once T4 is transported into the cell, it can then be acted on by deiodinases that can convert it to T3, which can stimulate metabolism or it can be acted on by deiodinases that convert it to reverse T3 and push it back out of the cell.
Most doctors don’t look at T3 because they don’t think it’s going to change too much, and most doctors don’t run reverse T3 because it’s not as important to what they are trying to accomplish. The guidelines pretty much have doctors focusing on TSH and T4 levels coming into normal range. It’s assumed that if those two values come back into normal range, then you’re getting sufficient levels of active thyroid hormone into the nucleus of all your cells and your thyroid physiology is corrected or fixed. Many times that’s just not the case. I’ve talked about this on multiple videos.
So what do you do?
You want to get T3, free T3, reverse T3 done, and your doctor doesn’t want to do it, what do you do? Listen, it’s your health. Ask them, tell them you want it done. Tell them you’ll take the responsibility. If it doesn’t get paid, then you’ll have to pay it. If you come to a functional medicine practitioner like me, you can get a full thyroid panel done for about $100, and that includes nine or 10 tests regarding thyroid physiology; TSH, T4, free T4, T3, free T3, reverse T3, T3 uptake, thyroid antibodies. You can get a lot of testing done for about $100. It’s your life, it’s your health, you want T3 done. Tell your doctor you want to get it done. Don’t just get T3 and free T3, make sure you get that reverse T3 number with it, and then make sure that you get the TSH, T4, free T4, T3 uptake, thyroid antibodies done as well. But it’s your health, ask your doctors or demand your doctors to run those tests, all right? Hopefully that helps. If you need help, give us a call at the office, I’d be more than happy to help you. Take care.
