The Wellness Library

Four Thyroid Labs Conventional Doctors Might Skip—And Why They’re Necessary to Help You Feel Better Faster

by | Jun 2, 2021 | Thyroid Health, Wellness

Dr Cassie tests a patient's pulse

Women are the most intuitive patients that I work with. When they tell me they just feel ‘off’ or that they are exhausted, anxious, constipated, and unable to lose weight no matter how well they stick to their clean diets—they’re usually onto something. After a few more questions from me to confirm or tie together symptoms, and we often run a full thyroid panel to make sure that everything is in working order.

Many times, I’m told by my female patients, “My primary care doctor already checked my thyroid and said that I was fine—it must be something I’m eating.” And here’s where it begins.

When a conventional medical professional “checks thyroid function,” they’re usually only running your TSH, or thyroid stimulating hormone. This is the brain hormone that is sent to your thyroid to tell it to get to work. If it’s within normal limits, your conventional doctor assumes your thyroid is working properly. From a functional medicine perspective, I’ve seen time and time again that this assumption doesn’t reveal the entire picture, and can leave patients suffering with low thyroid.

To get a deeper look into your thyroid function, there are are a few more tests that your doctor should run to get the full thyroid picture:

  • Free T4: T4 is the inactive thyroid hormone that is output by your thyroid gland. Measuring this tells us if your thyroid gland is actually outputting enough hormone to be utilized. The free, and bioavailable, form of T4 is the best to measure.
  • Free T3: The inactive T4 then gets converted (through enzymes called deiodinase enzymes) into active T3. T3 is what gives you the energy, metabolism, hair growth, and bowel regularity that many women are concerned about. This lab test tells us if your body is able to convert inactive thyroid hormone to active thyroid hormone in enough quantity to make you feel better and get your physiology up and running.
  • Reverse T3 (RT3): If your T3 cannot be taken up into your cells for any reason, it gets flipped around (hence, reverse T3, or the reverse of T3) and stored as an inactive product. We are finding that your pituitary gland (the part of your brain that releases TSH) can’t distinguish between actual T3, and RT3, and that higher levels of RT3 can trick your pituitary gland into thinking your thyroid is functioning normally, causing your TSH to be normal.
  • Thyroid Antibodies: Probably one of the most underdiagnosed thyroid dysfunctions is the autoimmune component, Hashimoto’s Thyroiditis. Without treatment of Hashimoto’s, the continual damage to the thyroid gland by these antibodies can create a non-functioning gland later in life. The antibodies to test for Hashimoto’s is anti-thyroglobulin and anti-thyroperoxidase.

Other Thyroid Factors: Reference Ranges

Another piece to the thyroid-lab testing puzzle is the out of date reference ranges. Many times, the reference ranges are very large, and many medical professionals skip over the subjective piece of how patients feel at the different values.

Let’s take TSH for example. Conventional reference ranges are generally 0.11 to 4.91 (it will vary depending on your lab company), and I can tell you from experience that a woman with a TSH closer to 0.11 (or closer to hyperthyroid) feels drastically different than a woman with a TSH over 2.5 (or closer to hypothyroid). However if you are within the conventional reference ranges, physicians will oftentimes tell you that “your thyroid is fine” and to “watch and wait.” My question? What the heck are they waiting for? For you to feel worse than you do now?

Next Steps to Better Thyroid Function

Once you have all of the thyroid values, with a full thyroid panel, you can then start to identify where in the thyroid hormone pathway your physiology is malfunctioning. This information allows us to personalize your treatment and target exactly what you need to get you feeling back to normal.

A final thought: It is imperative that no matter which thyroid labs come back abnormal, we treat the whole person. We rarely ever JUST run thyroid labs without adding in other tests that would show us a complete picture. Adrenal function, female hormone function, nutritional status, and metabolic status are all affected by and CAN AFFECT your thyroid function, so gathering that information is also key. It also helps us support your thyroid function from many different angles—which will expedite your healing process.

If you’re ready to get a deeper understanding of your thyroid function, or want to partner with a doctor who considers your whole person when diagnosing and treating you, reach out to get your questions answered.  



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