Lab Test Information

What Test Am I Buying?

-Reverse T3

Why Do I Need These?

Reverse T3 Patients who are found to have abnormal thyroid function tests—usually a low or normal TSH, low triiodothyronine (T3) and possibly a low thyroxine (T4). Determines whether a critically ill person truly is hypothyroid or a non-thyroidal illness syndrome, an rT3 is drawn.

In Non-thyroidal illness, also known as euthyroid-sick syndrome, refers to the reduced level of thyroid function blood tests found in the setting of severe illness in a person without preexisting thyroid dysfunction.

After recovery from the severe illness, the thyroid function test results should normalize.

In non-thyroidal illness syndrome, the rT3 is usually elevated, due to the body's suppression of certain enzyme activity.

In central hypothyroidism, the rT3 is low.With that, an elevated rT3 level in the setting of severe illness helps doctors exclude a diagnosis of hypothyroidism.

Is Fasting Required?

Fasting is required prior to taking this test. An ideal time to take this test is in the morning.

When Will My Results Be Ready?

Results are typically ready in 7-10 business days or less.


The laboratory services are for informational purposes only. It is not the intention of MYLABFAX LLC to provide specific medical advice but to provide users with information to better understand your health. Please speak to a medical professional about your results for proper diagnosis and treatment. 

Both the physician and the testing laboratory are independent contractors with whom MYLABFAX LLC makes arrangements for your blood tests. By Purchasing your lab tests through MYLABFAX you agree MYLABFAX LLC will NOT be held liable for any acts or omissions of the physicians, the testing laboratory, or their agents or employees.

Reverse T3

$ 109.00

Testing not available in: NY, RI, MD and NJ

How Does It Work?

Step 1: Order the lab test.
Step 2: Download and print the lab slip from your login page. 
Step 3: Locate your nearest Quest Diagnostics Laboratory from the 'lab locator' tab on your login page.
Step 4: Visit the laboratory with your slip to have your blood drawn.
Step 5: Results take 7-10 business days. An email will be sent requesting you to login to your page to access them.

For a more detailed explanation, please visit our step-by-step guide on ordering tests.

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