Your thyroid is a small gland that sits near the base of your throat. The thyroid makes thyroid hormones which are responsible for growth and energy production in the body, broadly speaking. Thyroid hormones regulate the basal metabolic rate (how much calories we burn each day), how we metabolize carbohydrates, proteins, and fat, and how hard our cardiovascular system works.

So you can understand that if you have a problem with your thyroid, this will have a big impact on your overall health.

But you would know if you have an issue with your thyroid, right? Wouldn't your doctor have tested your thyroid and told you if there was a problem?

Maybe. But more likely not.

You see, conventional medicine doesn't teach doctors how to properly assess thyroid function. They only teach doctors how to detect severe thyroid dysfunction. Because it is only when thyroid dysfunction is severe that conventional medicine can treat it (with drugs and surgery). Conventional medicine is not interested in knowing when your thyroid dysfunction is mild or moderate because they can do nothing to help you. So most doctors are not interested in looking for a problem if they can't fix it. So they don't run the right tests.

But lucky for you, there are doctors, such as myself, that know how to detect and treat all stages of thyroid dysfunction.

How the Thyroid Works

To help you understand your thyroid labs, we first need to discuss a little bit of thyroid physiology. But just a little bit.

The production of thyroid hormone by the thyroid gland is governed by the brain. When a gland in the brain, called the anterior pituitary, senses that there is not enough active thyroid hormone in the blood, it sends a messenger to tell the thyroid to make more hormone.

The messenger is called Thyroid Stimulating Hormone (TSH). This is the the screening test that doctors use to evaluate thyroid function.

In response to TSH, the thyroid makes more thyroid hormone, mostly in the form of the inactive hormone called T4. T4 is converted to the active hormone, T3, in the liver, kidneys, and brain.

T3 then enters all different types of cells in the body to send messages about energy production and growth.

Symptoms of Hypothyroidism:

If your body does not have enough active thyroid hormone (hypothyroidism), you may experience:

fatigue
weight gain
weakness
dry skin
mental sluggishness
hair loss & dry, course hair
constipation
cold intolerance

Symptoms of Hyperthyroidism

If your body has too much thyroid hormone (hyperthyroidism), you may experience:

excessive sweating
intolerance to heat
weight loss
muscle weakness
diarrhea
anxiety, nervousness, & excitability
inability to sleep
palpitations, increased heart rate, & increased blood pressure

The most common issue with the thyroid is hypothyroidism, meaning you don't have enough thyroid hormone.

Thyroid Labs

The standard method to evaluate the thyroid is to test TSH only. If TSH is high, this means the brain sensed low T3 levels, so it is now yelling at the thyroid to make more. If TSH is low, this means that the brain senses a lot of T3 in the blood. When TSH comes back abnormal, doctors will then usually test for T4 levels.

Sounds like a reasonable way to assess thyroid function indirectly. But here is the problem. The reference range for TSH is not accurate. According to the reference range, your thyroid function is normal if your TSH is anywhere between 0.5 to 8. That is a huge range of thyroid function.

The truth is most people feel the best when their TSH is between 1 and 2. And most people will feel like crap if their TSH is 4, let alone 8. When your TSH is 8, your thyroid is severely dysfunctional. Yet most doctors will not even further assess your thyroid function until your TSH is greater than 8. Until that time, they will tell you that your thyroid is fine and that there is nothing wrong with you.

I guess your fatigue, brain fog, digestive issues, depression, and hair loss must be all in your head.

If your TSH is greater than 2, it is time to get further evaluation. Either find a doctor who understands thyroid physiology or do it yourself. In many states, you can order your own lab tests online.

The Thyroid Labs You Need to Test

A complete thyroid evaluation includes:

TSH
free T4
free T3
anti-TPO
anti-TG
reverse T3 (optional)

What I often see is that people will have a TSH greater than 2 with free T4 and free T3 on the low end of normal. Again, most people feel the best when their thyroid hormones are on the upper end of the normal range. I like to see a free T4 around 1.5 and a free T3 around 3.5.

When your TSH is elevated (this may mean above 2 or even above 8) and your free T4 and free T3 are normal, this is called subclinical hypothyroidism. This is a bit of a misnomer because in this state, the labs are saying your thyroid is fine according to the reference ranges, but your body is telling a different story. You have all the signs and symptoms of hypothyroidism, just not the lab values.

If you have subclinical hypothyroidism, many doctors take a watch and wait approach. This means they plan on waiting until you get worse to do anything for you. Brilliant idea, right?

But most doctors miss a big piece of the puzzle. The antibodies. Anti-TPO and anti-TG are antibodies that your immune system makes to attack the thyroid gland. This happens in an autoimmune disease called Hashimoto's, which is the most common cause of hypothyroidism. To learn more about causes of hypothyroidism, read my blog post, Root Causes of Hypothyroidism.

After signing up for a free account, navigate to my favorites in the catalog to find thyroid support supplements.

References

Rettori V, Jurcovicova J, McCann SM. Central action of interleukin-1 in altering the release of TSH, growth hormone, and prolactin in the male rat. J Neurosci Res. 1987;18(1):179-83. doi: 10.1002/jnr.490180125. PMID: 3500324.

Ongphiphadhanakul B, Fang SL, Tang KT, Patwardhan NA, Braverman LE. Tumor necrosis factor-alpha decreases thyrotropin-induced 5'-deiodinase activity in FRTL-5 thyroid cells. Eur J Endocrinol. 1994 May;130(5):502-7. doi: 10.1530/eje.0.1300502. PMID: 8180680.

Kimura H, Caturegli P. Chemokine orchestration of autoimmune thyroiditis. Thyroid. 2007 Oct;17(10):1005-11. doi: 10.1089/thy.2007.0267. PMID: 17910527.

Capozzi A, Scambia G, Lello S. Subclinical hypothyroidism in women’s health: from pre- to post-menopause. Gynecol Endocrinol. Published online March 3, 2022:1-11. doi:10.1080/09513590.2022.2046728

Understanding Your Thyroid Labs through Integrative Medicine