Compare - Thyroid Test (LGC)

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: 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.

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 Compare - Thyroid Test (LGC) panel contains 3 tests with 4 biomarkers.

Why pay $99 for Lets Get Checked's Thyroid finger prick test kit when you can experience the convenience and affordablity of a Thyroid lab test with Ulta Lab Tests - compare now and save!

Brief Description: The Thyroid Lab Test is a crucial diagnostic evaluation that assesses the status of thyroid hormones and thyroid-stimulating hormone (TSH) in the blood. This test provides valuable insights into the functioning of the thyroid gland, a vital endocrine organ responsible for regulating metabolism and numerous physiological processes.

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 Thyroid Lab Test May Be Ordered

Timing of the Test: The Thyroid Lab Test can be ordered when specific symptoms or medical conditions warrant evaluation of thyroid function. It may also be included in routine health check-ups.

Reasons for Ordering the Test:

  1. Symptoms of Thyroid Dysfunction: Healthcare providers may order the Thyroid Lab Test when patients exhibit symptoms that suggest thyroid dysfunction. These symptoms can vary but commonly include fatigue, weight changes, mood disturbances, hair and skin changes, and temperature sensitivity.

  2. Thyroid Disorder Diagnosis: If a healthcare provider suspects a thyroid disorder based on clinical symptoms or physical examination findings, the Thyroid Lab Test is crucial for confirming the diagnosis and determining the type and severity of the disorder.

  3. Monitoring Thyroid Treatment: For individuals who have already been diagnosed with a thyroid disorder and are undergoing treatment (e.g., medication), regular thyroid function tests, including this one, are used to monitor the effectiveness of treatment and make necessary adjustments.

  4. Routine Health Check-Up: In some cases, the Thyroid Lab Test is included as part of routine health screenings, especially for individuals with known risk factors or family history of thyroid disorders.

What the Thyroid Lab Test Checks For

The Thyroid Lab Test checks for several essential markers related to thyroid health:

  • Free T3 (Triiodothyronine): This measures the level of the active thyroid hormone T3 in the bloodstream. T3 plays a crucial role in regulating metabolism and energy production.

  • Free T4 (Thyroxine): It measures the level of the inactive thyroid hormone T4 in the blood. T4 is converted into the active T3 in various tissues, and its measurement provides insights into thyroid hormone production by the thyroid gland.

  • Thyroid Stimulating Hormone (TSH): TSH is produced by the pituitary gland and regulates the thyroid gland's hormone production. Elevated TSH levels often indicate an underactive thyroid (hypothyroidism), while low TSH levels may suggest an overactive thyroid (hyperthyroidism).

How Health Care Providers Use the Results of the Thyroid Lab Test

Healthcare providers use the results of the Thyroid Lab Test to:

  1. Diagnose Thyroid Disorders: Abnormal levels of free T3, free T4, or TSH help diagnose thyroid disorders. For example, low free T3 and free T4 levels with elevated TSH may indicate hypothyroidism, while high free T3 and free T4 levels with low TSH may suggest hyperthyroidism.

  2. Determine Treatment Approach: The test results guide healthcare providers in determining the appropriate treatment approach. Hypothyroidism may require thyroid hormone replacement, while hyperthyroidism may involve medications or other therapies to suppress thyroid function.

  3. Monitor Treatment Efficacy: For individuals undergoing thyroid treatment, regular testing helps monitor the effectiveness of therapy. Adjustments to medication dosages can be made based on the test results to maintain thyroid hormone levels within the target range.

  4. Assess Overall Thyroid Health: In routine health check-ups or screenings, the test results provide insight into a person's thyroid health, helping identify early signs of thyroid dysfunction.

In summary, the Thyroid Lab Test, which includes markers for free T3, free T4, and TSH, is a fundamental tool for evaluating thyroid function. It plays a pivotal role in diagnosing thyroid disorders, guiding treatment decisions, and monitoring thyroid health, ultimately contributing to improved patient care and management of thyroid-related conditions.

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

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