What are Thyroid Biomarkers?
Thyroglobulin Antibodies (TgAb)
This test checks for antibodies created against thyroglobulin, a protein produced and used by the thyroid gland to make T3 and T4 hormones, which control metabolism and tissue/cell growth. If present, it may indicate thyroid-related autoimmune disorders, such as Hashimoto’s.
Example: It’s like your immune system is mistakenly attacking your thyroid’s factory workers who help build hormones.
How it’s measured: Measured through a blood test that detects antibodies against thyroglobulin.
Thyroid Peroxidase Antibodies (TPO)
This test checks for elevated antibodies created against thyroid peroxidase (TPO), an enzyme that helps produce hormones. If antibodies are detected, it can indicate thyroid-related autoimmune disorders, such as Hashimoto’s. When compared with abnormal TSH levels, it may also suggest Graves’ disease.
Example: Imagine your immune system breaking the tools (TPO) that your thyroid needs to make hormones.
How it’s measured: Measured through a blood test that identifies antibodies against thyroid peroxidase.
Thyroid-Stimulating Hormone (TSH)
About 1 in 5 women and 1 in 10 men have hypothyroidism, and a TSH test can help reveal thyroid issues. TSH is made by the pituitary gland and controls the release of thyroid hormones T3 and T4. Abnormal TSH combined with TPO results may indicate Graves’ disease.
Example: TSH is like the thermostat that tells your thyroid when to turn up or down hormone production.
How it’s measured: Standard blood test that measures the amount of TSH in your blood.
Thyroxine (T4) Free
This test is typically reviewed with TSH and T3 to understand thyroid function. T4 is made in the thyroid, travels in your blood, and gets converted into T3 in the liver and kidneys. Together, T4 and T3 support your metabolism, heart, brain, digestion, bones, and muscles.
Example: T4 is like the stored energy that your body turns into T3—the active fuel for many systems.
How it’s measured: Measured with a blood test that detects free (unbound) T4 hormone levels.
Triiodothyronine (T3) Free
T3 levels can show whether the thyroid is overactive (hyperthyroidism) or underactive (hypothyroidism or Hashimoto’s). T3 helps regulate body temperature, heart rate, cholesterol, memory, muscle aches, digestion, hair regrowth, and fertility.
Example: T3 is like the power switch for your metabolism and energy systems—it keeps everything running smoothly.
How it’s measured: Measured through a blood test that checks levels of unbound, active T3 hormone.
Iodine
Iodine is absorbed by the thyroid to make T4 and T3 hormones. It helps prevent goiters, supports protein production, and helps your body use oxygen effectively. Low iodine can affect thyroid health and hormone production.
Example: Iodine is like the raw material your thyroid needs to build its hormones.
How it’s measured: Measured with a urine or blood test. Often available as an add-on test.
Selenium
Selenium supports the thyroid, liver, and kidneys. It helps make the antioxidant glutathione, which reduces stress in your cells. It also stimulates thyroid hormones that influence metabolism, heart, brain, and muscle function.
Example: Selenium is like a mineral bodyguard—it protects cells and boosts thyroid performance.
How it’s measured: Measured via a blood test that assesses selenium levels in your serum or plasma.
