Hi, Dr Eric Balcavage and we are back for another edition of Thyroid Thursday. Today I want to talk to you about this myth that we see in healthcare, that you can evaluate thyroid physiology with just a TSH and a T4 in somebody’s blood work and determine whether or not they are hypothyroid at the cellular level.
Well, it doesn’t really matter how much T4 your thyroid makes (it does but what is more important is how much T4 and T3 get into your cells how much T4 is converted to T3 vs rT3). T4 is the inactive hormone in the body, it has to be converted into T3 to be used by the cells of your body. Just because your thyroid makes T4 doesn’t mean that it’s going to get into the cells, that it’s going to be converted from T4 to T3. That’s a lot of assuming when we just look at TSH and T4.
Another reason we can’t really use these markers as indicators of overall cellular function, is because TSH doesn’t really reflect overall cellular thyroid hormone status. What it really reflects is the amount of T3 in the pituitary gland The pituitary gland is unique in that it has its own distinct set of enzymes that convert T4 to T3, it has its own unique or distinct set of thyroid hormone transporter molecules and thyroid receptor molecules.
So, it’s really different than every other cell in the body, and the body will do what it has to do to keep the pituitary glands thyroid hormone status optimized even at the sacrifice of all the other cells of the body. The pituitary will stay in a non-hypothyroid state, yet all the other tissues of the body could be in moderate to severe hypothyroidism and your TSH and T4 would be normal. TSH via literature and the current research is just not a good marker of cellular thyroid health and that’s what’s most important.
T4 is not a great market either. So, why is that?
Well, T4 is the inactive hormone, it has to get transported into the cells to be converted to T3. The conversion or the transport of T4 to T3 at the cellular level requires a lot of energy, and unfortunately any condition which causes us to have a reduction in cellular energy; things like insulin resistance, diabetes, chronic inflammation, or any number of chronic health conditions, decreases our cellular systems ability to make energy. Therefore, those transporter molecules aren’t going to work as well. If the transporter molecules can’t transport T4 into the cell, then there’s less T4 in the cell to be converted into T3, therefore cellular metabolism can go down.
So, T4 levels could look normal or high and you could still have all the symptoms of hypothyroidism. So, when doctors are constantly doing a TSH level for their patients who complain of hypothyroid symptoms and tell them there is nothing wrong with their thyroid physiology, they are way off base. Doctors who are determining whether they have the right levels of thyroid hormone prescribed to somebody just based on a TSH and T4 value are again mismanaging their patients, because they are not looking at some of the more important markers.
So, if TSH and T4 aren’t good values to evaluate somebody’s cellular thyroid hormone status, what markers could you use?
I always recommend a full thyroid panel when you get your thyroid levels tested. That would include a TSH, T4, fT4, T3, fT3, rT3, FTI, T3U, TPO Ab, Tg Ab. When you run that full panel, two important calculations that should be performed to evaluate cellular thyroid hormone status, (what’s in the cells of your body), is the T3 to rT3 ratio or the fT3 to rT3 ratio. If those values are out of what the normal range is, or the optimal range is, then the person who is struggling with cellular hypothyroidism will have all the symptoms of hypothyroidism regardless of what their TSH and T4 values are.
So, next time your doctor tells you there’s nothing wrong with your thyroid hormone status or that you’re not hypothyroid and he’s only run the TSH and T4, you’ve got to demand either a full thyroid panel or you’ve got to come see somebody like me, who understands thyroid physiology, functional medicine and understands these ratios of T3 to rT3 and fT3 to rT3, so that we can help you optimise your cellular health by giving you the right support.
Hopefully that gives you some extra insight. I look forward to talking to you on another Thyroid Thursday. If you ever have any questions regarding thyroid physiology and whether there is something we can do to help you, by all means, give us a call at the office, 610-558-8920, or put a comment in the area below on the website and we’ll get back to you as soon as possible. Have a great day.
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