The thyroid gland is an endocrine gland located in the front of the neck. The thyroid gland affects virtually every organ in the body. It secretes hormones ‐ T3 and T4 ‐ which regulate metabolism, including how fast the body burns calories and how fast the heart beats. TSH regulates the production of T3 and T4. Measurement of TSH is the foundation for assessing thyroid function. TPOAb is an antibody made by the immune system that suppresses thyroid hormone production.
The levels of these markers indicate whether your thyroid is over-functioning or under-functioning.
According to the American Thyroid Association, more than 12% of the population may end up dealing with a thyroid condition at some point in their lives. Of the nearly 20 million Americans living with a thyroid condition, 60% don’t realize it.
How the Markers Work in the Body
Thyroid hormones regulate the speed with which the cells work ‐ everything from how fast the heart beats to how quickly the intestines process food. Understanding how these markers are produced and how they function is critical to understanding the importance of a healthy thyroid.
Thyroid-stimulating hormone (TSH ) is produced by the pituitary gland at the base of the brain. Once TSH is produced, it moves to the thyroid gland, activating the production of the primary thyroid hormones, triiodothyronine (T3) and thyroxine (T4) . This synthesis process is made possible by the enzyme thyroid peroxidase (TPO) .
It is important to have stable thyroid hormone levels. The human body has a unique feedback loop in which the brain and the pituitary and thyroid glands communicate to monitor and maintain hormone levels.
When blood levels of T3 and T4 are low, the pituitary gland releases more TSH to signal the thyroid gland to produce more primary thyroid hormones.
If T3 and T4 blood levels are high, the pituitary gland releases less TSH to slow production of these hormones.
When T3 and T4 act on target organs and tissues (heart, fat, bone, muscle, etc.), they initiate increased energy production and cell growth. An underactive thyroid (also known as hypothyroidism) doesn’t produce enough T3 and T4 , which slows your body’s metabolism process, decreasing energy production and cell growth. In some cases, such as autoimmune-related thyroiditis, TPO is attacked by the immune system via TPO Antibodies . Thus, the detection of circulating TPOAbs indicates an autoimmune-related condition and generally means the thyroid gland will be resistant to the action of TSH.
You should take this test if you:
Are an adult age 40+
Feel sluggish and fatigued
Have difficulty losing weight
Feel cold often
TSH • Blood Spot
Normal range is 0.5 – 3.0 μU/mL
A hormone produced in the brain that tells the thyroid gland to make T3 and T4. Measurement of TSH is the foundation for assessing thyroid function.
Free T3 • Blood Spot
Normal range is 2.4 – 4.2 pg/mL
One of the two major hormones made by the thyroid gland. It regulates metabolism, body temperature, weight, energy, and heart health.
Free T4 • Blood Spot
Normal range is 0.7 – 2.5 ng/dL
T4 is the hormone made in the greatest quantity by the thyroid gland. It can also be converted to T3. It has the same actions as T3, but it’s not as strong.
TPOAbs • Blood Spot
Normal range is < 150.0 IU/mL
TPOabs are unwanted antibodies made by the immune system that suppress thyroid function.
How it works
1 • Delivered
After purchasing, all home-test materials are delivered to your door
2 • Locate Barcode
Locate the barcode included with your kit and enter at thorne.com
3 • Complete Collection
Complete your test collection and return with prepaid shipping
4 • Reviewed
Your results are reviewed by an independent board-certified physician
5 • Receive Results
You’ll receive your results & personalized recommendations within 7-9 days
Levels of the four thyroid-related biomarkers tested can indicate whether your thyroid is under-functioning (hypothyroidism) or over-functioning (hyperthyroidism).
Symptoms Related to Underactive Thyroid
An underactive thyroid gland doesn’t produce enough T3 and T4.
As a result, you may experience:
Joint and muscle pain
Sensitivity to cold
Cold hands and feet
Dry skin and hair
Frequent, heavy periods
Slowed heart rate+
Swelling in the neck from an enlarged thyroid gland
+Slowed heart rate (bradycardia) – commonly less than 60 beats per minute
Symptoms Related to Overactive Thyroid
An overactive thyroid gland produces higher than normal amounts of T3 and/or T4.
As a result, you might experience:
Unexpected weight loss+
Nervousness, anxiety, and irritability
Tremors in hands or fingers
Changes in menstrual patterns
Increased sensitivity to heat
More frequent bowel movements
Swelling in the neck from an enlarged thyroid gland
Fatigue and muscle weakness
Fine, brittle hair
+ Unexpected weight loss, even when your appetite and the amount and type of food you eat remain the same or even increase
++ Rapid heartbeat (tachycardia) — commonly more than 100 beats a minute; or irregular heartbeat (arrhythmia); or pounding of your heart (palpitations)
What the tests tell you
Simple visualization of your biomarker results over time, plus detailed descriptions of each biomarker for an easy interpretation of your overall health.
Insights based on your results help you identify potential health risks or areas of improvement.
Access your diet, activity, and supplement plan anytime, anywhere through the Thorne dashboard. Recommendations are generated from our medically-supervised algorithms based on your unique test results.