top of page

Essential4Health

Get Healthy ~ Stay Healthy

Essential4Health

Get Healthy ~ Stay Healthy

lab-scientists-blood-urine-test-analysis

Triiodothyronine Free-to-Triiodothyronine Reverse Ratio

different-type-serum-containing-blood-samples

FT3 / RT3

Description

Triiodothyronine Free to Triiodothyronine Reverse Ratio test looks at the balance between active T3 (triiodothyronine) and inactive reverse T3 in your body, helping doctors understand how well your thyroid is functioning and how it’s impacting your metabolism. It’s often used to check for thyroid imbalances, like hypothyroidism, or conditions linked to chronic stress. A blood sample is taken during the test to ensure that your thyroid hormones are in balance. An imbalance in the ratio may indicate thyroid or adrenal issues. This test is especially useful for those who are fatigued, experiencing brain fog, or noticing unexpected weight changes. The results provide your doctor with important information for confirming a diagnosis and developing a treatment plan, which may include hormone therapy, lifestyle changes, or additional tests. Keeping track of this ratio on a regular basis can help you maintain good thyroid and metabolic health.

Triiodothyronine Free to Triiodothyronine Reverse Ratio test looks at the balance between active T3 (triiodothyronine) and inactive reverse T3 in your body, helping doctors understand how well your thyroid is functioning and how it’s impacting your metabolism. It’s often used to check for thyroid imbalances, like hypothyroidism, or conditions linked to chronic stress. A blood sample is taken during the test to ensure that your thyroid hormones are in balance. An imbalance in the ratio may indicate thyroid or adrenal issues. This test is especially useful for those who are fatigued, experiencing brain fog, or noticing unexpected weight changes. The results provide your doctor with important information for confirming a diagnosis and developing a treatment plan, which may include hormone therapy, lifestyle changes, or additional tests. Keeping track of this ratio on a regular basis can help you maintain good thyroid and metabolic health.

Procedure

Invasive

Sample Type

Blood – Serum

Test Category

Hormones

Procedure Category

Blood Draw

Units

Ratio

Test Groups

Complete Thyroid Group: A comprehensive array of tests for a thorough evaluation of thyroid function, providing detailed insights into thyroid health and associated conditions.

Optimal Range

For All Individuals:

  • Conventional Unit: >0.20 R

  • SI Unit: Not Applicable

Normal Range

For All Individuals:

  • Conventional Unit: 10.0–20.0 R

  • SI Unit: Not Applicable

Results That Differ From The Norm (Direct and Indirect Causes)

Abnormal results may indicate:


  • Burn injuries

  • Euthyroid sick syndrome (Thyroid hormone abnormalities in critically ill patients)

  • Medications (such as glucocorticoids or amiodarone)

  • Non-thyroidal illness (Conditions affecting thyroid function due to factors unrelated to thyroid pathology)

  • Rheumatoid arthritis (Chronic inflammatory disorder affecting the joints)

  • Severe caloric restriction

  • Severe Trauma (Physical injury or wound)

  • Starvation (Prolonged absence of food intake)

  • Systemic lupus erythematosus (Autoimmune disease causing inflammation in various parts of the body)

Key Reasons For Testing

  • Thyroid Function Assessment: Evaluates the balance between active and inactive thyroid hormones to diagnose thyroid disorders.

  • Tissue-Level Thyroid Status Insights: Provides insights into thyroid activity at the tissue level, uncovering hidden discrepancies.

  • Thyroid Hormone Therapy Prediction: Predicts therapy effectiveness, guiding dosage adjustments for optimal outcomes.

  • Peripheral Thyroid Conversion Evaluation: Assesses T4 to T3 conversion to understand thyroid hormone metabolism.

Health Status Conditions It May Be Used To Assess

Currently, this test is not directly associated with any conditions listed on the Health Status page. However, it may be included as part of a broader set of tests linked to specific health conditions.

Some Prominent Medical Labs That May Offer This Test

Please note that this particular test has not been associated with any of the listed prominent medical labs. We recommend enquiring with your private physician or nearest hospital to determine where this specific test can be performed.

References

Important Note

Any medical procedure yielding results outside the norm may be directly or indirectly linked to the conditions outlined on this page. Various factors, including genetics, medication and supplement usage, recent illnesses, pregnancy, pre-test eating, smoking, and stress, can impact the test's outcome. Additionally, factors like false positives, false negatives, inaccurate analyses, and others can influence results.


Reference ranges, which help healthcare professionals interpret medical tests, may vary depending on age, gender, and other factors. They may also differ between laboratories due to variations in instruments and methods used. Optimal ranges are designed for preventive purposes, aiming to identify trends and potential risks early, while normal ranges reflect conventional laboratory values indicating no current disease or pathology. Your healthcare practitioner may have specific reasons for testing that deviate from the usual or may interpret results differently based on individual circumstances. Proper interpretation typically involves considering clinical findings and other diagnostic tests. Hence, it is crucial to provide your healthcare professionals with a comprehensive medical history, consult with them for result interpretation, and follow their guidance for potential re-testing or additional diagnostics.

Disclaimer

This content is provided solely for informative and educational purposes. It is not intended as a substitute for medical advice or treatment from a personal physician. Regarding the interpretation of their medical test results and/or specific health questions, it is recommended that all readers and viewers consult their physicians or other qualified health professionals. The publisher is not responsible for any adverse health effects that may result from reading or following the information in this educational content. Before beginning any nutrition, supplement, or lifestyle program, all viewers, especially those taking prescription or over-the-counter medications, should consult their physician or health care practitioner.


Please note that while prominent lab names are included in this content, we cannot guarantee that these labs offer all the tests mentioned. For confirmation, individuals should contact the labs directly or consult their medical practitioners. The information provided reflects general knowledge at the time of publication and may not include recent updates or emerging research. Readers should verify details with qualified professionals to ensure the most up-to-date and accurate guidance.

[1] Chopra IJ. A study of extrathyroidal conversion of thyroxine (T4) to 3,3',5-triiodothyronine (T3) in vitro. Endocrinology. 1976;98(5):1271-1280.
[2] Vagenakis AG, Burger A, Portnay GI, et al. Diversion of peripheral thyroxine metabolism from activating to inactivating pathways during complete fasting. J Clin Endocrinol Metab. 1975;41(1):191-194.
[3] Huang SA, Bianco AC. Reawakened interest in type III iodothyronine deiodinase in critical illness and injury. Nat Clin Pract Endocrinol Metab. 2008;4(3):148-155.
[4] Sabatino L, Ambrosio R, De Angelis C, et al. Thyroid hormone metabolism and action in mitochondria. Horm Metab Res. 2007;39(7):443-449.
[5] Brenta G. Why can insulin resistance be a natural consequence of thyroid dysfunction? J Thyroid Res.2011;2011:152850.
[6] Warner MH, Beckett GJ. Mechanisms behind the non-thyroidal illness syndrome: an update. J Endocrinol.2010;205(1):1-13.
[7] Wiersinga WM. Nonthyroidal illness and euthyroid sick syndrome. In: Braverman LE, Cooper DS, eds. Werner & Ingbar's The Thyroid: A Fundamental and Clinical Text. 10th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:273-288.
[8] Peeters RP. Low triiodothyronine (T3) syndrome in critical illness: to treat or not to treat? Crit Care. 2006;10(6):324.
[9] Fliers E, Wiersinga WM. Nonthyroidal illness and the low-T3 syndrome. In: Endotext [Internet]. Updated 2018.
[10] Kaptein EM, Weiner JM, Robinson W, et al. Peripheral serum thyroxine, triiodothyronine, reverse triiodothyronine, and thyrotropin kinetics in patients with acute renal failure. Circ Shock. 1983;11(2):163-173.
[11] Ciloglu F, Peker I, Pehlivan A, et al. Exercise intensity and its effects on thyroid hormones. Neuro Endocrinol Lett.2005;26(6):830-834.
[12] Chopra IJ, Taing P, Mikus L. Direct determination of free triiodothyronine (T3) and free reverse triiodothyronine (rT3) in serum by equilibrium dialysis/radioimmunoassay. Metabolism. 1983;32(11):1097-1107.
[13] Gavin LA, Hammond ME, Derubertis FR. Thyroid hormone modulation of rat liver mitochondrial alpha-glycerophosphate dehydrogenase and other pathways of oxidative metabolism. Endocrinology. 1979;104(6):1824-1830.
[14] Lim VS, Fang VS, Katz AI, Refetoff S. Thyroid dysfunction in chronic renal failure. A study of the pituitary-thyroid axis and peripheral turnover kinetics of thyroxine and triiodothyronine. J Clin Invest. 1977;60(3):522-534.

If You Like This, You Might Like...

bottom of page