Dr. David Clark, DC Center for Low Thyroid Solutions Durham, NC reveals yet another reason why you are still suffering hypothyroid symptoms.
Hidden cause #6 why you still have low thyroid symptoms, even though your lab numbers are "normal", and even though you're taking thyroid medication, is
High Levels of Thyroxine Binding Globulin (TBG)
This taxi cab, you know the thyroid hormones, the T4 and the T3, they jump inside the cab and they get transported to the liver where they’re converted.
And then they jump back in the cab and they’re transported to the rest of the body. So they must have this little carrier to go anywhere.
An elevation in thyroxine binding globulin (TBG) means there’s a whole bunch of taxi cabs.
In fact, there’s so many cabs (carrier proteins called TBG) that the normal free amount of T4 and T3 that should be floating around isn't. It’s as if they all get sucked up like a big sponge by all these thyroid binding globulins.
Here's the crummy part about all this....
Your TSH will look normal. Your total T4 will look normal. Your total T3 will look normal.
If that’s all the markers your doctor is checking, then this problem is completely missed. You’ll be given thyroid hormones but you probably won’t get better.
Now you might have a little bit of a hormone honeymoon where you feel better for a couple of weeks, but eventually you’ll go right back to having depression, weight gain, hair loss, feeling cold, no motivation, brain fog. You’ll suffer those low thyroid symptoms again.
What causes elevated TBG? Estrogens are particulary good at elevating TBG. Now estrogens come in a lot of different forms, right? Estrogens can be hidden in face creams. Estrogens are in birth control pills. Estrogens can be elevated in a woman who’s not detoxifying her estrogens normally (liver issue).
So you see already we’ve kind of gone down the rabbit hole a little bit in tracking down the source of the elevated TBGs causing low thyroid symptoms.
If your doctor is not considering binding globulin as a possible problem, then he/she's missing part of the reason why you could still be having thyroid symptoms.
If your TBGs are too high---Even though TSH is normal and T4 looks normal and total T3 looks normal---if your doctor will check your T3 uptake, or T3U, he/she will see tt that the T3U actually low.
(there is an inverse relationship between T3 uptake and binding globulins-one high and the other low).
Remember there’s also a lab reference range for T3U. The lab's range is typically too forgiving. So, YOUR numbers might be within the lab's range and look "normal"--but really your numbers are abnormal if you used a narrower range, a functional range.
Estrogens hanging out in the body elevate binding globulins, which suck up all the free T4 and T3.Therefore, not enough of the FREE T3 gets out of the taxi to attach to the T3 receptors....
...and you have low thyroid symptoms, but your labs look normal and you’re still taking medication.
Birth control pills contain estrogens. Some face creams and cosmetics contain undisclosed estrogens (not naming brands) . These estrogens can also elevate if you are not detoxifying estrogens normally. Let’s talk about that briefly...
Hormones are detoxified through the liver. So, if you have poor liver function, poor detoxification function, this is one of the reasons why you could still have a thyroid problem. It’s not a thyroid gland problem; it’s a liver problem really in this case.
Take this a step further.....what would cause someone to have poor detoxification in their liver? The biggest factor is blood sugar regulation. Glucuronidation is one of the liver processes you use to detoxify hormones. The "gluco" means glucose. If you don’t have normal, steady glucose to supply your liver, then you can’t detoxify appropriately.
And see what happens? You can’t just look at thyroid hormone symptoms things from the surface. You’ve got to dig down deep and understand the physiology in order to really help someone who hasn’t been helped yet.
So what types of blood sugar problems are we talking about? Low blood sugar and high blood sugar. High blood sugar means there’s nothing getting into the cells. Usually that’s from insulin resistance and that can be caused by cortisol. The other variety of a blood sugar problem is low blood sugar or reactive hypyglycemia. These are the people that get shaky and lightheaded and irritable between meals. Now these people don’t have any blood in their cells because they just don’t eat anything or something is shutting down their cortisol.
I don’t want to get too far off into that, but the point is...
a Thyroxine Binding Globulin problem is one reason that you could have low thyroid symptoms but have normal lab numbers, even though you’re taking medication.
I hope that you’re seeing a doctor that understands that TBGs have to be on the radar.
And if you find binding globulins that are elevated, why are they elevated?
So that’s where the detective work kicks in. You’ve got to put on your thinking cap and start doing the appropriate testing and finding out is it a liver problem, is it birth control pills?
What’s actually happening here? And it’s only when you start to turn over every one of these rocks, and do a comprehensive workup on someone from a functional perspective that you can help someone that’s been suffering forever with low thyroid symptoms because what they might actually have is Elevated Thyroxine Binding Globulin problem.
And taking replacment thyroid hormones aren’t going to help.
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© 2010 Dr. David Clark
THE PLACE FOR ANSWERS™
Dr. David Clark
Diplomate College of Clinical Nutrition
Board Certified Chiropractic Neurologist
Vestibular Rehab Specialist