Knowing optimal thyroid levels is key to being able to understand how your thyroid is functioning. It’s also helpful so that you can be your own best advocate for your health.
Most practitioners only test TSH, so it’s very important to ask your practitioner for a thyroid panel. Getting a look at what’s actually going on with your thyroid will give you and your practitioner more insight as to what steps to take next.
Here’s the list of labs to ask for (if your doctor won’t order labs for you, you can order them here:
I also recommend getting a CBC, CMP with phosphorus, iron panel, saliva cortisol test and Vitamin D. Various nutrient deficiencies or other imbalances in the body can cause thyroid numbers to be too high or too low, so it’s important to look at the values in these tests.
Let’s dive in to the optimal thyroid levels:
What is TSH and what is a “normal” level?
TSH is a hormone that the pituitary sends out to tell the thyroid how much or how little thyroid hormones to produce. Please note: TSH levels tell you what your pituitary is up to, but it’s not telling you how much or how little thyroid hormone is being produced.
Everyone is biochemically individual, but in general, a TSH level between 0.5-2.0 mIU/L is the optimal functional range where people feel healthy and vibrant.
To read about how to lower TSH naturally, click here.
To read about how to increase TSH naturally, click here.
What is free T4 and what is a “normal” level?
Free T4 (free thyroxine) is a hormone produced by the thyroid. In general, it’s optimal for free T4 to be in the middle of the lab range. So, if the range is 1.0-3.0 ng/dL, you want your free T4 to be 2 or close to it. Each lab has a different range, so you have to look at what the specific range is to know what number to look for.
What causes elevated FT4?
Most often, FT4 is high because there is a severe form of either emotional or environmental stress (from things such as synthetic pesticides, toxic metals, and possibly glyphosate).
FT4 can also be elevated because TSI is mimicking TSH and telling the thyroid to make excess FT4. There is also a negative feedback loop between TSH and FT4, so sometimes FT4 can be elevated when TSH is too low.
Free T4 can also be elevated if you happen to be on too much thyroid hormone, so it’s always good to talk to your doctor or pharmacist about this possibility.
What causes low free T4?
Oftentimes, free T4 is low because the thyroid doesn’t have the resources to produce the proper amount of T4. The thyroid needs iodine and tyrosine to produce thyroid hormones. Increasing the consumption of iodine-rich foods, reducing exposure to chlorine, fluoride and bromine (this is incredibly important!), and taking an iodine supplement can often help improve this imbalance. If you’re concerned about taking iodine when you have thyroid disease, read this post and it should answer your questions.
Remember to talk to your nutritionist or a practitioner who’s had lengthy training in nutrition to help you figure out what kinds of supplements your body needs. Self-prescribing and self-dosing often doesn’t go well, so it’s worth paying a practitioner for their expertise.
Free T4 can also be low when antibody levels are elevated. When antibodies attack the thyroid tissues, this can make it difficult for the thyroid to produce enough fT4.
Another thing to keep in mind is that there is a negative feedback loop between TSH and free T4, so sometimes free T4 can be low when TSH is elevated.
What is free T3 and what is a “normal” level?
Free T3 is a hormone that mostly comes from free T4. The thyroid makes free T4 and sends most of it to the liver to be converted to free T3.
In general, it’s optimal for free T3 to be in the middle of the lab range. So if the range is 1.0-3.0 pg/mL, you want your free T3 to be 2 or close to it. Each lab has a different range, so you have to look at what the specific range is to know what number to look for.
What causes low free T3?
Here are three common reasons why free T3 can be low.
1. Free T3 can be low because there isn’t enough free T4 being produced by the thyroid to be converted into free T3.
2. If there are adequate levels of free T4, but there isn’t enough free T3, then this often indicates liver congestion.
Let me explain. . .
Your thyroid produces T4 and sends most of it to the liver to be converted into the active form, free T3. If you have enough free T4, but not enough free T3, then you don’t necessarily have a thyroid problem, instead, you may need to support your liver so it can efficiently convert T4 to T3 for you.
Liver congestion is pretty common nowadays, and can not only cause low T3 in the body, but can also cause estrogen dominance, severe headaches, blood sugar imbalance, chemical sensitivities, skin issues, and dark circles under the eyes, among other things. Here is an article I wrote with specific steps you can take to improve this issue.
What causes elevated FT3?
Here are a few reasons why FT3 can be too high:
1. The thyroid is making too much T4 that is being converted to FT3.
2. When there is toxicity somewhere in the body, this can increase FT3.
3. Being on too much thyroid hormone can also cause elevated FT3, so it’s always good to talk to your doctor or pharmacist about this possibility.
To read more about steps to take when thyroid hormones are elevated, click here.
What are TPO antibodies (anti-TPO), and what is a “normal” level?
TPO (thyroid peroxidase) is the key enzyme that helps your thyroid make thyroid hormones. Anti-TPO is an antibody that attacks TPO. This is the lab that is most often used to diagnose Hashimoto’s.
A normal anti-TPO level is usually <30 IU/mL. Keep in mind that it’s normal to have a small amount of TPO antibodies in the blood.
What is TgAb and what is a “normal” level?
TgAb (thyroglobulin antibodies), sometimes referred to as TAA (thyroid antithyroglobulin antibody) are antibodies that attack thyroglobulin. Thyroglobulin is a protein produced and used by the thyroid to make T3 and T4.
A normal TgAb level is 0 IU/mL.
What are TSI antibodies, and what is a “normal” level?
The TSI antibody (sometimes referred to as TRAb or TSHR) is an antibody that mimics TSH by telling the thyroid to make excess FT4. This also often creates an excess of FT3 and a decrease in TSH.
In some cases, the TSI antibody blocks thyroid hormone production instead. A normal TSI level is <1.
Positive TSI results are strongly indicative of Graves’ disease, but do not always correlate with the presence and severity of hyperthyroidism.
What is Reverse T3 and what is a “normal” level?
Reverse T3 (RT3) is one of the three primary thyroid hormones that is made from T4. Some T4 is converted into RT3, which is an inactive form of T3.
Because RT3 is an inactive thyroid hormone, it doesn’t regulate or stimulate production within the cells. Instead, it acts as a cellular braking system to prevent the overstimulation of excessive free T3.
Free T3 is like the gas pedal that revs the engine up, and reverse T3 is the brake that slows things down. As you can see, it’s very important to get RT3 testing so you can know if your body has the right amount of energy going out to the body’s cells.
In general, it’s good to see RT3 <15 ng/dL. The normal ratio of total T3 to RT3 should be 10-12:1. If you are below this ratio, this indicates a form of hypothyroidism, even when TSH is low. If you are above this ratio, you may need less T3 and/or more T4 in the body.
What Causes Elevated RT3?
In general, excess cortisol and/or severe, prolonged stress causes elevated RT3. The body creates the RT3 to keep from creating too much free T3 and going into overdrive.
Click here to learn steps to take to reduce reverse T3 naturally.
If you’re reading this article and looking over your labs and feeling some anxiety, I want to encourage and remind you that there are things you can do with diet, supplements, medications, stress reduction, detox, etc. to help balance the thyroid and/or immune system.
Thyroid disease is a symptom of other things off-balance in the body. The good thing about this is that there is always something that we can do to help improve the situation! My hope is that this information will help you better understand your thyroid labs so that you can have a more educated conversation with your doctor. You are your best health advocate!
Here is some further reading on optimal thyroid levels and root causes:
If you’d like to learn some first steps you can take to help support your thyroid, check out my class, “3 Keys to Thyroid Hormone Balance”. It’s just 45 minutes and I promise you’ll learn something new!
Note: The purpose of this post is to give an overview of thyroid lab ranges from a holistic perspective. Due to biochemical individuality there can be many various reasons for the root causes of thyroid disease, levels that might be optimal for you because of your individual circumstance, and many ways to help improve thyroid in balance in the body. This information is not intended to take the place of your doctor’s advice.