TSH with Reflex to Free T4

The TSH with Reflex to Free T4 test contains 1 test with 1 biomarker.

Description: A TSH test is a blood test that measures thyroid stimulating hormone levels in your blood’s serum and is used to screen for and monitor treatment of thyroid disorders such as hypothyroidism and hyperthyroidism. This test can reflex into a T4 Free Test.

A T4 Free test is a blood test that measures thyroxine free levels in your blood’s serum to evaluate your thyroid’s health and to screen for, diagnose, and monitor thyroid disorders such as hypothyroidism.

Also Known As: Thyroid Stimulating Hormone, Thyrotropin, TSH test, Thyroid Test, TSH Screen, Free T4, Free Thyroxine, FT4 Test, T4F, T4 Free, Unbound T4, TSH with Reflex to FT4 Test

Collection Method: Blood Draw

Specimen Type: Serum

Test Preparation: No preparation required

Note that this is a Reflex test.  If initial TSH testing determines that additional testing is required, the lab will automatically charge for T4, Free #866

When is a TSH with Reflex to Free T4 test ordered?

When a person has symptoms of hyperthyroidism or hypothyroidism, or an enlarged thyroid gland, a doctor may order a TSH test.

Hyperthyroidism can cause the following signs and symptoms:

  • Heart rate has increased.
  • Anxiety
  • Loss of weight
  • Sleeping problems
  • Hand tremors.
  • Weakness
  • Diarrhea
  • Visual disturbances, light sensitivity
  • Puffiness around the eyes, dryness, discomfort, and, in some cases, bulging of the eyes are all possible side effects.

Hypothyroidism can cause the following signs and symptoms:

  • gaining weight
  • Skin that is dry
  • Constipation
  • Intolerance to the cold
  • Skin that is puffy
  • Hair loss is a common problem.
  • Fatigue
  • Women's menstrual irregularities

When a person is being treated for a thyroid disease, TSH may be ordered at regular intervals. The American Thyroid Association suggests waiting 6-8 weeks after changing a person's thyroid medication dose before testing their TSH level again.

In the United States, TSH screening is routinely performed on newborns shortly after birth as part of each state's newborn screening program.

What does a TSH with Reflex to Free T4 blood test check for?

The pituitary gland, a small structure beneath the brain and beyond the sinus cavities, produces thyroid-stimulating hormone. TSH causes thyroxine and triiodothyronine to be released into the bloodstream by the thyroid gland. These thyroid hormones aid in the regulation of the body's energy usage. This test determines how much TSH is present in the blood.

The feedback mechanism that the body utilizes to maintain consistent quantities of thyroid hormones in the blood includes TSH and its regulatory hormone, thyrotropin releasing hormone, which comes from the hypothalamus. TSH synthesis by the pituitary gland increases as thyroid hormone concentrations fall. TSH stimulates the thyroid gland, a small butterfly-shaped gland that lays flat against the windpipe at the base of the throat, to produce and release T4 and T3. Thyroid production turns on and off to maintain generally steady levels of thyroid hormones in the blood when all three organs are operating regularly.

When the thyroid produces excessive amounts of T4 and T3, the affected person may have hyperthyroidism symptoms such as high heart rate, weight loss, agitation, hand tremors, itchy eyes, and difficulty sleeping. The most prevalent cause of hyperthyroidism is Graves disease. It is a chronic autoimmune condition in which the immune system creates antibodies that mimic TSH, causing the thyroid hormone to be produced in excessive levels. As a result, the pituitary gland may produce less TSH, resulting in a low blood level.

Weight gain, dry skin, constipation, cold intolerance, and weariness are all symptoms of hypothyroidism, a condition in which the thyroid produces fewer thyroid hormones. In the United States, Hashimoto thyroiditis is the most prevalent cause of hypothyroidism. It's an autoimmune disease in which the immune system attacks the thyroid, causing inflammation and destruction as well as the generation of autoantibodies. The thyroid generates low levels of thyroid hormone in Hashimoto thyroiditis. The pituitary gland may create more TSH, resulting in a high blood level.

TSH values, on the other hand, do not necessarily indicate or predict thyroid hormone levels. TSH is produced abnormally in some persons and does not work properly. Despite having normal or modestly increased TSH values, they frequently develop hypothyroidism. Thyroid hormone levels can be high or low in a variety of thyroid illnesses, regardless of the amount of TSH in the blood.

TSH levels may be elevated or lowered in rare cases due to pituitary dysfunction. In addition to pituitary dysfunction, an issue with the hypothalamus can cause hyperthyroidism or hypothyroidism.

Lab tests often ordered with a TSH with Reflex to Free T4 test:

  • T3 Free
  • T3 Total
  • T4 Free
  • T4 Total
  • T3 Reverse
  • T3 Uptake
  • Thyroid Peroxidase
  • Thyroglobulin Antibodies
  • Thyroid Panel
  • Thyroid Panel with TSH

Conditions where a TSH with Reflex to Free T4 test is recommended:

  • Hyperthyroidism
  • Hypothyroidism
  • Hashimotos
  • Graves’ Disease
  • Autoimmune Diseases
  • Thyroid Cancer

How does my health care provider use a TSH with Reflex to Free T4 test?

Thyroid function and/or symptoms of a thyroid problem, such as hyperthyroidism or hypothyroidism, are frequently assessed with the thyroid-stimulating hormone test.

The pituitary gland, a small structure beneath the brain and beyond the sinus cavities, produces TSH. It's a part of the body's feedback system that keeps the thyroid hormones thyroxine and triiodothyronine in check and helps regulate the pace at which the body burns calories.

TSH tests are typically ordered in conjunction with or before a free T4 test. A free T3 test and thyroid antibodies are two further thyroid tests that can be ordered. TSH, free T4, and free T3 are sometimes ordered as part of a thyroid panel.

TSH is used to:

  • Diagnose a thyroid issue in a patient who is experiencing symptoms.
  • Check newborns for an underactive thyroid.
  • Monitor thyroid replacement therapy.
  • Monitor treatment of hyperthyroidism that involves medication.
  • Assist women in diagnosing and monitoring infertility issues.
  • Assist in determining the pituitary gland's function
  • Screen adults for thyroid issues and diseases.

Free thyroxine tests are used to assess thyroid function and detect thyroid disorders, such as hyperthyroidism and hypothyroidism, after the thyroid stimulating hormone level has been found to be abnormal.

The thyroid gland produces T4 and another hormone called triiodothyronine. They aid in the regulation of the rate at which the body expends energy and are governed by a feedback system. TSH promotes the thyroid gland's synthesis and release of T4 and T3.

The majority of T4 and T3 in the blood is attached to protein, while just a small amount is free. Total T4, free T4, total T3, and free T3 can all be measured in blood testing. The total T4 test has been around for a long time, but it is influenced by the quantity of protein in the blood that can bind to the hormone. The active form of thyroxine, free T4, is unaffected by protein levels. Many people believe that the free T4 test is a more accurate reflection of thyroid hormone activity, and it has largely supplanted the total T4 test.

A free T4 test can be used in conjunction with or after a TSH test, and occasionally with a free T3 test to:

  • Help diagnose the cause of hyperthyroidism and hypothyroidism by detecting too much or too little thyroid hormone.
  • Differentiate between thyroid disorders.
  • Assist in the diagnosis of pituitary diseases
  • Assist in the diagnosis of infertility in women
  • In an individual with a known thyroid condition, track the effectiveness of treatment.
  • Monitor patients with pituitary disease to ensure that their thyroid is still operating, and thyroid hormone medication should be monitored if it isn't.
  • Monitor patients with thyroid cancer whose tumors respond to TSH. TSH and T4 levels will be monitored on a regular basis to ensure that adequate thyroid hormone is being administered to maintain TSH low while keeping T4 high.

In the United States, babies are routinely tested for T4 and TSH levels to rule out congenital hypothyroidism, which can lead to mental retardation if left untreated.

Thyroid abnormalities can sometimes be detected using free T4 and TSH, however professional opinions differ on who should be screened and when they should start.

Thyroid antibodies, as well as a free T4 test, may be ordered if a health practitioner suspects someone has an autoimmune-related thyroid problem.

What do my TSH with Reflex to Free T4 test results mean?

A high TSH level could indicate that:

  • The person being examined has an underactive thyroid gland that isn't responding well to TSH stimulation owing to acute or chronic thyroid dysfunction.
  • If a person has hypothyroidism or has had their thyroid gland removed, the dose of thyroid hormone replacement medicine may need to be changed.
  • A patient with hyperthyroidism is taking too much anti-thyroid medication, and the dosage needs to be reduced.
  • There is a problem with the pituitary gland, such as a tumor that causes TSH levels to be out of control.

A low TSH level could imply the following:

  • An overactive thyroid gland
  • Thyroid hormone prescription taken in excess by patients being treated for an underactive thyroid gland.
  • Inadequate anti-thyroid medication in a person being treated for hyperthyroidism; nevertheless, after successful anti-thyroid treatment, TSH production may take a time to recover. This is why the American Thyroid Association recommends testing for thyroid hormones as well as TSH levels throughout treatment.
  • The pituitary gland has been damaged, preventing it from releasing enough TSH.

An abnormal TSH result, whether high or low, suggests an excess or deficiency in the quantity of thyroid hormone available to the body, but does not pinpoint the cause for the abnormal result. Additional testing is frequently performed after an abnormal TSH test result to determine the reason of the increase or decrease.

In general, high free T4 levels suggest an overactive thyroid gland, while low free T4 levels suggest an underactive thyroid gland. The test results are not diagnostic in and of themselves, but they will urge the health care provider to conduct additional testing to determine the reason of the excess or deficiency.

A range of temporary and chronic thyroid disorders are linked to both decreased and increased free T4 levels. A pituitary gland issue could be indicated by low free T4 levels along with a low TSH level, or by high free T4 levels combined with a high TSH.

When thyroid tests are done to monitor treatment for thyroid or pituitary diseases, the results will tell the doctor whether the treatment is working and/or if a dose adjustment is required. People with hyperthyroidism, for example, have their free T4, free T3, and TSH levels examined on a regular basis while taking anti-thyroid medicines to ensure that the drugs are effective and to reduce doses if thyroid hormone levels fall too low. TSH and free T4 levels are monitored on a frequent basis in hypothyroid patients to ensure that the correct dose of thyroid hormone is being given to bring TSH levels back to normal.

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

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: Thyroid Stimulating Hormone with Reflex To FT4 , TSH WReflex To Ft4

TSH W/Reflex To Ft4

*Process times are an estimate and are not guaranteed. The lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance.

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