Your results come back and there is one number on the page. TSH.
If you have ever been tempted to read that one number as the whole picture, know that TSH is not a thyroid test at all. It is your pituitary gland asking your thyroid for more.
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Health with Hashimoto’s is your free weekly podcast that sorts this autoimmune condition into thyroid or immune. Each episode is for informational and educational purposes. Please discuss any questions or concerns with your trusted healthcare professional. Some links may be affiliate links, marked as such, at no extra cost to you.
The seven thyroid labs to ask for
Here is the full list I want every single time I have my thyroid panel done.
Thyroid function
- TSH
- Free T4
- Free T3
- Reverse T3
Immune function
- TPO antibodies (thyroid peroxidase)
- TG antibodies (thyroglobulin)
- Vitamin D
That is seven labs. Most women get one.
Sorting them into two columns is not a filing trick. Hashimoto’s involves two systems, not one. Four of these tell you how well your thyroid gland is doing its job, and three tell you about the immune system that is attacking it.
If you already have results in hand and want to know what each number means, I covered that in what do my thyroid labs mean. This post is about what to ask for before the blood draw.
TSH is not a thyroid test
The first thing that usually gets checked is your TSH. That is not your thyroid at all. It is your brain, by way of your pituitary gland, asking for more thyroid hormone.
Think of it as a request being repeated. Please, can I have more. Please, can I have more.
The higher your number, the harder your body is asking. So a high TSH means your thyroid hormones are low, at least as far as your body is concerned.
It is a useful number. It is just not a measurement of what your thyroid is producing.
Free T4 and free T3 show what your body can actually use
Your thyroid makes T4. Your body then converts that T4 into T3.
T4 is the inactive form. It is what your thyroid makes, but it is not what your body can use. T3 is the active form.
Free T4 is the T4 available in your blood. Free T3 is the T4 that has already been converted and is free to use.
Those two numbers answer the question TSH cannot. How much is your thyroid actually producing, and how much of it is available to you?
Reverse T3 is the brake system
Your body does not always convert T4 into T3.
Your body knows that T3 activates your cells. It is the little ignition switch. The gas pedal.
And sometimes your body decides it does not want more energy. It wants more rest, because we heal when we are resting. So it takes that T4 and converts it into reverse T3 instead.
That is the brake system. Instead of giving you energy, it slows you down.
Personally, I want to know my reverse T3 because I want to know how much my body is asking me to rest. If that number is going up, I need to prioritize downtime. I need to prioritize getting into my parasympathetic nervous system (rest and digest) and getting extra sleep at night, because my body is requiring it.
Medication makes this number more important, not less. Synthroid and levothyroxine are T4 only. Your body still has to do the converting.
So if you are taking your medication faithfully and still do not feel better, this might be part of why. Your body has the T4. It is just not turning it into the gas pedal.
Episode 94 goes through T3, free T3, and reverse T3 in more detail.
Your antibodies are the only labs that measure the attack
Hashimoto’s is an autoimmune problem. It is not a problem of the thyroid. It is a problem of your immune system, and your immune system is attacking your thyroid.
So what we want to know is whether the attack is strong. How much of it is happening? Are your levels going up or down?
We learn that by testing the antibodies. With Hashimoto’s there are two. TPO (thyroid peroxidase) and TG (thyroglobulin).
Ask for both.
Nothing else on this list tells you anything about the attack itself. Your TSH will not. Your free T4 will not.
The antibodies are the only place your immune system shows up on a lab report.
Why vitamin D belongs on your thyroid panel
I also really want to know my vitamin D level.
Vitamin D is innately tied to your immune system. It impacts so many different things in your immune system, and it directly impacts one of those antibody levels.
That is why I put it on the same requisition as the other six, even though it is not a thyroid test.
When to get your thyroid labs drawn
As early in the morning as possible, in a fasted state.
Sometimes your provider or your lab will tell you it does not matter. It actually does. Your TSH drops throughout the day.
If you want an accurate number, the most accurate one comes from the earliest draw.
What to do if you cannot get all seven ordered
Some physicians and practitioners will order these without being asked. Sometimes you have to ask specifically.
And sometimes your doctor’s hands are tied by the insurance company and they cannot order things unless you decide to pay on your own.
That is what episode 39 is about, going beyond the TSH and ordering your own labs. It applies mostly to people in the United States.
Note: The cheapest place I could find at the time of recording episode 39 was Ulta Labs. Since dropping health insurance and joining Knew Health instead, I use their lab, Evexia which helps me save significantly more. I’m an affiliate for Knew Health. Use code HWH20 for 20% off your first year.
There are two or three states where the legislature has decided not to give you autonomy over your own labs and restricts you from ordering them yourself. (It is ridiculous.)
If you live outside the US, check what is available where you are. I have talked to people in other countries where this is not an option at all.
Go deeper on each of these labs
Each of these episodes runs about 20 minutes.
- Episode 3, what do my thyroid labs mean
- Episode 39, beyond TSH, how to order your own labs in the US
- Episode 80, T4 versus free T4
- Episode 94, T3, free T3, and reverse T3
- Episode 9, low vitamin D and Hashimoto’s
- Episode 62, how to pick a vitamin D supplement
Frequently asked questions about thyroid labs
What to do with this list
You now know the difference between a lab that measures your thyroid and a lab that measures your immune system. You know which thyroid labs to ask for. You know to go early and fasted.
It is up to you and your provider what you actually get. But remember, you are the CEO of your own health. Your provider is on your team to give you the best advice, and now you can make the best decisions with that advice.
This post is for informational and educational purposes only. Please discuss any concerns and plans with your trusted healthcare professional.
Your next appointment is where this gets used. Write the seven down and take them with you, and if you want the questions to go with the labs, 10 Thyroid Questions to Ask Your Doctor is free and built for exactly that conversation.