What to Look for in Thyroid Panels

Thyroid panels are VERY important blood tests.  But like most tests, they do not exist in isolation.  

Please join me for a tour of ALL the thyroid tests that should be included in "a panel", what their "normal levels" vs "Ideal levels" are, as well as some additional tests that you can consider, after discussing with your primary care provider if they're right for you :)

Before we begin, allow me to introduce myself.  I am Dr. Kelly Sadauckas (said-OW-skiss, thanks for asking), a double board certified pelvic floor expert who has made it her life's work to reduce geophraphic, psychosocial and financial barriers to kick-arse pelvic health care and information.  I'm glad you're here.  Now, without further ado: 

What is your thyroid and why is it important?  

Your thyroid is a small gland on the front of your neck, just beneath your Adam's apple.  It secretes hormones (along with the pituitary gland) to help control the speed of your metabolism, energy, cardiovascular and neurological systems, and overall growth and development (Armstrong, et al, 2023)

It is important because if it gets wonky, your metabolism, available energy, cognitive function, heart function and even your ability to regulate temperature!  

What to look for in a thyroid panel!

When your doctor orders a thyroid panel, it should NEVER be "just one test".  We truly do need a minimum of 4 tests to get a general picture of your thyroid's health. 

0. The hypothalamus releases Thyrotrophic Releasing Hormone (TRH)  

This is NOT a standard test in a thyroid panel. 5-25 Units/mL would be considered normal, but remember this is not a common test to run, as it exists only transiently to activate TSH.  

1. Thyroid Stimulating Hormone (TSH)

This IS a key test in a thyroid panel.  TRH stimulates the anterior pituitary gland to release TSH.  

TSH values are "normal" between 0.3-3, and are a measure of what your brain is requesting, and drives the Thyroid to produce T3 and T4.

2. Free T3

This tells us what level of thyroid hormones our cells are actually receiving.  Optimal results are 3.2-4.4mg/dL.

3. Free T4 (Thyroxine)

This tells us how much of the primary thyroid hormone (Thyroxine) is present in our blood. Optimal levels are 1-1.5ng/dL

4. Reverse T3 

Reverse T3 tells us if our bodies are converting Thyroxin into the inactive form. Optimal levels are <15ng/dL).

5. TPO Antibody

TPO antibody tells us if our bodies are actively attacking the thyroid gland for any reason. Ideal values here are 0.

All of these numbers, in conjuction will give you a picture of how healthy your thyroid gland is.  T3 and T4 in the blood work to tell the thyroid it is doing a good job, and that it can stop producing more T3 and T4. This balance is called "homeostasis".  

What other tests CAN be useful along with a thyroid panel?

That's a loaded question, and whole-heartedly depeends on your reasons for getting the thyroid panel in the first place. 

If you have low energy, ferritin and an iron panel can be useful to see how much iron your body has available to it.  Ferritin will ideally be >50 in a menstruating female, and in athletes values of >90 are preferred.  

If you have low energy, your A1C is also a useful test.  It measures your blood sugar over time, and can cue your doctor into any developing insulin sensitivity, which would change your energy availability. 

A general "total blood count" or CBC is also a useful tool just to see how your overall red and white blood cells are doing.  It can identify a broader disorder or issue.  

Are hormone panels useful when thyroid dysfunction is suspected? 

If by hormone, you mean Estrogen, Testosterone and Progesterone, then the answer is (you guess it), yes AND it depends!

Estrogen, Testosterone and Progesterone all affect thyroid function, through various direct and indirect ways. 

1. Estrogen and Thyroid Levels & Function

High Estrogen levels, like those from oral contraception, pregnancy or oral hormone replacement therapy, INCREASE the liver's production of Thyroid Binding Globulin.  As its name implies, Thyroid Binding Globulin binds free thyroid hormones (T3 and T4), leaving less "free thyroid hormones" to circulate.  This is important because it means that excessive Estrogen (via pills or a SLOW digestive tract) can result in less thyroid function, and the resultant symptoms of fatigue, weight gain, etc. If you are taking a thyroid medicine, this also means that you might need to adjust the dosage if you start a higher dose oral contraceptive.

TRANSDERMAL ESTROGEN (through a patch) bypasses the liver's metabolism, and therefore does NOT alter Thyroid Binding Globulin in the same way that oral Estrogen does.  

2. Progesterone and Thyroid Levels & Function

Progesterone acts as "the keeper/balancer of Estrogen" and therefore helps to lower the amount of thyroid binding globulins in the blood.  This means that a healthy progesterone level can allow more active thyroid hormones to be present, assisting in ideal thyroid function. 

If your progesterone is LOW, however (which is the FIRST THING that happens in perimenopause, the 10-year period before menopause), this results in a relatively Estrogen-Dominant state, which can then result in the elevated levels of Thyroid Binding Globulin in the blood, and can mimic or amplify hypothyroid like symptoms of fatigue and weight gain.

Testosterone and Thyroid Levels & Function

Testosterone is the least direct player in the Thyroid game.  According to the British Thyroid Foundation, normal replacement doses of Testosterone do not typically alter thyroid function or interfere with medication. 

Thyroid Function is related to Testosterone, and sometimes slightly reduced TSH or T4 levels are seen in men with hypogonadism.  Additionally very high doses (like anabolic steroid use) can disrupt normal thyroid function, so users should be aware of that risk (amongst others)!.  

That's the summary of what you should look for in a thyroid panel (and more)!

I truly hope you learned something new today.  If you did, please share this with friends, family and coworkers.  We are on a mission to save the world, one pelvis at a time, and need your help to do that!  Thanks for being here!

 XOXO
Dr. Kelly  💋

It's true! You can look it up!

Armstrong M, Asuka E, Fingeret A. Physiology, Thyroid Function. [Updated 2023 Mar 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537039/

British Thyroid Foundation: https://www.btf-thyroid.org/thyroid-and-menopause-article

Santin AP, Furlanetto TW. Role of estrogen in thyroid function and growth regulation. J Thyroid Res. 2011;2011:875125. doi: 10.4061/2011/875125. Epub 2011 May 4. PMID: 21687614; PMCID: PMC3113168.

Sheehan MT. Biochemical Testing of the Thyroid: TSH is the Best and, Oftentimes, Only Test Needed - A Review for Primary Care. Clin Med Res. 2016 Jun;14(2):83-92. doi: 10.3121/cmr.2016.1309. Epub 2016 May 26. PMID: 27231117; PMCID: PMC5321289.