FT3, FT4, TSH, TPO, TgAB and RT3 Panel

The following is a list of what is included in the item above. Click the test(s) below to view what biomarkers are measured along with an explanation of what the biomarker is measuring.

Also known as: Reverse T3, Reverse Triiodothyronine, RT3, T3 Reverse RT3 LCMSMS, Triiodothyronine Reverse

T3 Reverse, LC/MS/MS

Reverse T3 produced in the thyroid comes from the conversion of the storage hormone T4. Your body, especially the liver, can constantly be converting T4 to RT3 as a way to get rid of any unneeded T4. In any given day approx. 40% of T4 goes to T3 and 20% of T4 goes to Reverse T3. However in any situation where your body needs to conserve energy and focus on something else, it will change the above percentages, changing the conversion of RT3 to 50% or more, and the T3 goes down, down. Examples are emotional, physical, or biological stress, such as being chronically or acutely sick (the flu, pneumonia, etc), after surgery, after a car accident or any acute injury, chronic stress causing high cortisol, being exposed to an extremely cold environment, diabetes, aging, or even being on drugs like beta blockers and amiodarone.

Also known as: Free T3, FT3, T3 Free

T3, Free

This test measures the amount of triiodothyronine, or T3, in the blood.

Also known as: Free T4, FT4, T4 Free

T4, Free

The free T4 test is not affected by protein levels. Since free T4 is the active form of thyroxine, the free T4 test is may be a more accurate reflection of thyroid hormone function.

Thyroglobulin Antibodies

Measurement of thyroglobulin antibodies is useful in the diagnosis and management of a variety of thyroid disorders including Hashimoto's thyroiditis, Graves Disease and certain types of goiter.

Thyroid Peroxidase

Also known as: Thyroid Stimulating Hormone, Thyroid Stimulating Hormone (TSH), Thyrotropin


A TSH test is a lab test that measures the amount of thyroid stimulating hormone (TSH) in your blood. TSH is produced by the pituitary gland. It tells the thyroid gland to make and release thyroid hormones into the blood.


*Important Information on Lab Test Processing Times: Ulta Lab Tests is committed to informing you about the processing times for your lab tests processed through Quest Diagnostics. Please note that the estimated processing time for each test, indicated in business days, is based on data from the past 30 days across the 13 Quest Diagnostics laboratories for each test. These estimates are intended to serve as a guide and are not guarantees. Factors such as laboratory workload, weather conditions, holidays, and the need for additional testing or maintenance can influence actual processing times. We aim to offer estimates to help you plan accordingly. Please understand that these times may vary, and processing times are not guaranteed. Thank you for choosing Ulta Lab Tests for your laboratory needs.

The FT3, FT4, TSH, TPO, TgAB and RT3 Panel panel contains 5 tests with 7 biomarkers.

Brief Description: The FT3, FT4, TSH, TPO, TgAB, and RT3 Panel is a comprehensive set of tests that provides a thorough assessment of thyroid function and autoimmune activity affecting the thyroid gland. This panel is critical for diagnosing, monitoring, and managing various thyroid disorders. It evaluates the levels of thyroid hormones, the presence of antibodies that target thyroid proteins, and the regulation of thyroid activity.

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: Specifc to TSH: Specimen collection after fluorescein dye angiography should be delayed for at least 3 days. For patients on hemodialysis, specimen collection should be delayed for 2 weeks.

According to the assay manufacturer Siemens: "Samples containing fluorescein can produce falsely depressed values when tested with the Advia Centaur TSH3 Ultra assay."

When and Why the FT3, FT4, TSH, TPO, TgAB, and RT3 Panel May Be Ordered

This panel is often ordered when symptoms suggest thyroid dysfunction, such as unexplained weight changes, mood swings, changes in energy levels, or when there is a family history of thyroid disease. It's also used to monitor patients with known thyroid conditions or to evaluate the effectiveness of thyroid treatment. The comprehensive nature of this panel allows for a detailed understanding of thyroid health, encompassing not just hormone production but also potential autoimmune influences.

What the FT3, FT4, TSH, TPO, TgAB, and RT3 Panel Checks For

T3 Reverse (RT3)

Reverse T3 is a metabolite of thyroid hormone production, often increasing when the body is under stress or when it needs to conserve energy by slowing down metabolism. High levels can indicate that the body is not using thyroid hormones efficiently.

T3 Free (FT3)

Free T3 measures the unbound, active form of triiodothyronine, a key hormone produced by the thyroid gland that regulates metabolism. Abnormal levels can indicate hyperthyroidism or hypothyroidism.

T4 Free (FT4)

Free T4 measures the unbound, active form of thyroxine, another primary hormone produced by the thyroid. It is converted to T3 in the body's tissues. Altered levels can also suggest hyperthyroidism or hypothyroidism.

Thyroid Peroxidase Antibodies (TPO)

TPO antibodies target the enzyme in the thyroid gland that is essential for producing thyroid hormones. Their presence often indicates autoimmune thyroid disease, such as Hashimoto's thyroiditis or Graves' disease.

Thyroglobulin Antibodies (TgAB)

TgAB antibodies target thyroglobulin, a protein involved in thyroid hormone production. Like TPO antibodies, their presence can signal autoimmune thyroid disorders.

Thyroid Stimulating Hormone (TSH)

TSH, produced by the pituitary gland, regulates the production of thyroid hormones. It is a key indicator of thyroid health, with abnormal levels pointing to hyperthyroidism or hypothyroidism.

Conditions or Diseases Detected by the FT3, FT4, TSH, TPO, TgAB, and RT3 Panel


Characterized by insufficient thyroid hormone production, leading to a slowdown in metabolic processes. High TSH and low FT3 and FT4 levels typically indicate this condition.


Marked by excessive thyroid hormone production, accelerating metabolism. Low TSH and high FT3 and FT4 levels usually suggest hyperthyroidism.

Hashimoto's Thyroiditis

An autoimmune disorder leading to the gradual destruction of the thyroid gland, resulting in hypothyroidism. High levels of TPO and TgAB antibodies are common.

Graves' Disease

Another autoimmune disorder, but it causes hyperthyroidism due to antibodies stimulating the thyroid to produce too much hormone. TPO or TgAB antibodies may be elevated, alongside low TSH and high FT3 and FT4 levels.

Using the Results in Treatment and Monitoring


For hypothyroidism, treatment typically involves thyroid hormone replacement therapy. Regular monitoring of TSH and FT4 levels helps adjust medication dosage to ensure hormonal balance.


Treatment options include antithyroid medications, radioactive iodine, or surgery. Monitoring involves assessing TSH, FT3, and FT4 levels to ensure effective treatment and prevent complications.

Hashimoto's Thyroiditis

Management focuses on symptom relief and hormone level normalization, often through thyroid hormone replacement. Regular monitoring of TSH and FT4, along with antibody levels, guides treatment adjustments.

Graves' Disease

Treatment may include antithyroid medications, radioactive iodine therapy, or surgery. Monitoring TSH, FT3, and FT4 levels, along with antibody titers, is essential for managing the disease effectively.

The FT3, FT4, TSH, TPO, TgAB, and RT3 Panel provides a comprehensive evaluation of thyroid function and autoimmune activity, crucial for diagnosing and managing thyroid diseases. By assessing hormone levels and the presence of specific antibodies, healthcare professionals can develop targeted treatment strategies, monitor disease progression, and adjust therapies as needed to manage conditions effectively and improve patient outcomes. This panel is an essential tool in the ongoing effort to understand and treat thyroid disorders comprehensively.

We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.

Customer Reviews