Which blood tests you need and why…
How can you improve your thyroid health if you don’t know what’s wrong with it? Blood tests can help you discover what you need to know, so you can take effective and appropriate actions to change your health for the better.
Why guess when you can test…and find out for sure?
Your thyroid plays a crucial role in regulating metabolism, energy production, and overall well-being, yet many people suffer from thyroid dysfunction without a way to fix it. If you’re experiencing a thyroid problem a comprehensive thyroid panel can help you get the answers you have been looking for. But how do you uncover what’s really going on?
The answer lies in the right blood tests. Standard thyroid screenings do not offer the tests that can provide useful information you can use to improve your health and thyroid function. In this article, we’ll break down the essential blood tests that provide a complete picture of thyroid function, immune health, and inflammation—so you can take informed action and regain control of your health.
Thyroid Tests
Thyroid health impacts metabolism and energy, with hormone levels like TSH, T4, and T3 indicating potential imbalances. Abnormal levels may signal conditions like hypothyroidism or hyperthyroidism, often linked to autoimmune disorders or inflammation. Monitoring thyroid function is essential for maintaining overall well-being.
TSH (Thyroid-Stimulating Hormone)
Measures the hormone that comes from your pituitary gland and stimulates the thyroid gland to produce thyroid hormone. High levels may indicate hypothyroidism, while low levels suggest hyperthyroidism. TSH must be evaluated with the levels of thyroid hormones for useful interpretation.
T4 (Thyroxine)
The measures the total amount of T4 hormone circulating in the blood. Low levels can indicate hypothyroidism, while high levels may suggest hyperthyroidism.
Free T4 (Thyroxine)
This test measures how much of your T4 is not stuck to a protein. T4 must be detached or “free” from its carrier protein to be biologically active. These binding proteins are evaluated through the T3U test (see below).
T3 (Triiodothyronine)
This measures the total amount of T3 hormone. T3 is the active form of thyroid hormone and comes from the other thyroid hormone T4. Low levels may indicate poor conversion of T4 into T3 and or low levels of T4.
Free T3 (Free Triiodothyronine)
Thyroid hormone is only active if it does not have a protein attached to it. FreeT3 measures how much of your T3 is “free” and not attached to a carrier protein. Free T3 is the most active form of thyroid hormone. (see T3U below)
Reverse T3 (rT3)
Measures an inactive form of T3 that can increase during stress, chronic illness, or inflammation, preventing normal thyroid hormone function. Learn more about the Reverse T3 test now.
T3U (T3 Uptake)
Measures the level of proteins that carry thyroid hormone in the blood. This test reflects assessment of thyroxine-binding globulin (TBG). Despite its name, T3 uptake does not directly measure the uptake of T3 into cells but instead evaluates the extent to which thyroid-binding proteins are saturated with thyroid hormones.
Thyroid Peroxidase Antibodies (TPOAb)
The TPO Antibody test helps identify autoimmune thyroid diseases like Hashimoto’s and Graves’ disease.
Thyroglobulin Antibodies (TgAb)
The TgAb test helps diagnose autoimmune thyroid disorders such as Hashimoto’s disease and Graves’ disease.
Thyroid-Related Tests
Thyroid function is deeply influenced by factors such as inflammation, blood sugar control, and stress. When these elements are imbalanced, they can disrupt hormone production and conversion, leading to thyroid-related issues. A well-regulated thyroid is crucial for optimal energy levels and overall bodily health.
hs-CRP (High-Sensitivity C-Reactive Protein)
Measures inflammation levels in your body. Inflammation makes thyroid problems worse and thyroid problems make inflammation worse. It’s a vicious circle.
Ferritin
Checks iron storage, which is crucial for thyroid hormone function and energy metabolism. Elevated ferritin can also indicate inflammation. See Iron Test below.
HbA1c
Measures long-term blood sugar levels. The test shows average blood sugar levels over the past 90 days (approximately). HbA1c levels are often higher in patients with hypothyroidism compared with control subjects. Elevated blood sugar is inflammatory to the body.
Insulin
Measuring your insulin level while fasting helps assess insulin resistance, which can impact thyroid function and overall immune response. Insulin resistance results in inflammation which interferes with the regulation of thyroid gland from the hypothalamus and pituitary gland as well as conversion of T4 into its active form T3.
Cortisol
Cortisol is a hormone that is produced by your “stress glands.” Cortisol has many functions in your body, such as mediating the stress response, regulating metabolism, the inflammatory response, and immune function. High levels of cortisol hamper thyroid regulation and reduce the conversion of T4 into the active form T4. Chronically elevated cortisol is one of the reasons prolonged stress is damaging to the body in general.
Homocysteine
Elevated homocysteine levels can indicate potential vitamin deficiencies and genetic factors (MTHFR gene) that may affect the body’s ability to utilize amino acid properly. Homocysteine is a key determinant of the methylation cycle. “Studies suggest that impaired methylation may cause some genes to inappropriately turn on, which can lead to increased risk of thyroid concerns. Dysfunctional methylation and inappropriate activity of genes sends inflammatory messages that causes immune cells to attack the thyroid.”
Complete Blood Count (CBC) with Differential
Evaluates white blood cells, red blood cells, and platelets to detect infections, immune response issues, or anemia (which is common with thyroid dysfunction). Thyroid dysfunction can cause changes in your red and white blood cells. Your white blood cells are your immune system cells and your red blood cells carry oxygen to your cells so they can make the energy needed to maintain health and survival.
Comprehensive Metabolic panel (CMP)
A comprehensive metabolic panel (CMP) is a blood test that measures proteins, enzymes, electrolytes, minerals and other substances in your body. It’s a test that can help provide a picture of your overall physical health. Comprehensive Metabolic Panel.
- Glucose
- BUN
- Creatinine
- eGFR
- BUN/Creatinine ratio
- Sodium
- Potassium
- Chloride
- Carbon dioxide
- Calcium
- Protein (total)
- Albumin
- Globulin
- A/G ratio (Albumin/Globulin)
- Bilirubin (total)
- Alkaline Phosphatase
- AST (SGOT)
- ALT (SGPT)
Thyroid Nutrient Tests
Nutrients play a vital role in supporting healthy thyroid function, influencing hormone production and conversion. Deficiencies in key vitamins and minerals like iodine, selenium, and zinc can impair thyroid performance, while balancing levels of iron, vitamin D, and B12 can help regulate metabolism and immune function. Proper nutrition is essential for maintaining thyroid health and preventing related complications.
Iodine
Essential for thyroid hormone production (T3 & T4). However, excessive iodine can worsen autoimmune thyroid diseases like Hashimoto’s. “Eating foods that have large amounts of iodine—such as kelp, dulse, or other kinds of seaweed, and certain iodine-rich medicines—may cause hypothyroidism or make it worse.”
Selenium
Required for thyroid hormone conversion (T4 to T3) and reduces thyroid inflammation. Selenium is an antioxidant and protects your cells from free radical damage.
Zinc
Necessary for thyroid hormone synthesis and immune function. Low levels can impair T3 production. “Zinc is a trace mineral and is necessary for almost 100 enzymes to carry out vital chemical reactions. It is a major player in the creation of DNA, growth of cells, building proteins, healing damaged tissue, and supporting a healthy immune system.”
Copper
It plays an essential role in thyroid metabolism and thyroid hormone production. Copper stimulates the creation of thyroxine (T4). “The deficiency of copper decreases protein-bound iodine production by the thyroid gland (necessary for the production of thyroid hormone).”
Iron
Critical for thyroid hormone production and oxygen transport. It is important to remember that your thyroid hormones promote energy production and metabolism but none of these beneficial effects can happen if your cells don’t get enough oxygen. Iron (found in your hemoglobin in red blood cells) is what transports oxygen to your cells. Iron is the most common trace mineral deficiency. “Your body is dependent upon iron to convert thyroxine (T4) into the active hormone triiodothyronine (T3) via thyroid peroxidase (TPO). As such, low iron levels can impede thyroid function, and patients can present with hypothyroid-like symptoms.”
Vitamin D
Regulates immune function and reduces inflammation. Vitamin D is also classified as a hormone. Deficiency is linked to autoimmune diseases like Hashimoto’s. It is essential for immune regulation and inflammation control. “This encourages the advisability of… screening for Vitamin D deficiency… for all hypothyroid patients.”
Vitamin B12
Essential for energy production, nerve health, and immune function. Many thyroid patients are deficient. “1 in 4 patients with either hypothyroidism or subclinical hypothyroidism suffer from a vitamin B12 deficiency. Patients with hypothyroidism had lower levels of vitamin B12 when compared with healthy participants, according to a study published in Frontiers in Endocrinology.” Vitamin B12 is essential for healthy red blood cells and white blood cell formation.
Folate (folic acid)
The terms “folate” and “folic acid” are often used interchangeably. However, folate is a general term used to describe many different forms of vitamin B9. Folic acid plays several roles in thyroid hormone production and hormone conversion: It helps change T4 into T3, the more active form of thyroid hormone. Folic acid protects thyroid cells from damage. “Folic acid is essential for thyroid health. It helps produce DNA and supports cell growth and repair, which are crucial in maintaining thyroid function. The thyroid gland regulates metabolism, and folic acid contributes to energy production by aiding red blood cell formation.”
Secure Your Blood Test For Thyroid Health Package
Your thyroid health is too important to leave to guesswork. Getting the right blood tests is the first step toward understanding the root cause of your symptoms and making informed decisions about your health. Don’t settle for incomplete testing—advocate for yourself and ensure you’re evaluating all the critical markers of thyroid function, immune balance, and inflammation.
Now is the time to act. Get a comprehensive thyroid panel, track your results, and implement lifestyle changes that support healing. Your health is in your hands—start today and take the steps necessary to restore balance, energy, and vitality.
This article by Dr. Clint Sexton and Sexton Functional Medicine is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider regarding your individual health concerns. Reading this article does not establish a doctor–patient relationship.
