Product Details

• Persistent hypothyroid-type symptoms: Fatigue, cold sensitivity, weight change or low mood.
• Low energy or slowed metabolism: Reduced exercise tolerance or ongoing metabolic slowing.
• Inconsistent thyroid results: Further assessment when routine thyroid markers do not fully explain symptoms.
• Chronic illness or physiological stress: Evaluation where wider systemic factors may be affecting thyroid hormone conversion.
• Thyroid treatment review: Additional assessment in individuals using thyroid hormone therapy with ongoing symptoms.
• Further thyroid investigation: When standard thyroid testing does not fully explain the clinical picture.

Reverse T3 is a blood test that measures reverse triiodothyronine, an inactive form of thyroid hormone produced during conversion from T4. Measuring reverse T3 can provide additional insight into thyroid hormone conversion beyond standard thyroid tests.

Altered levels may help provide clinical context in individuals with ongoing symptoms of low thyroid activity, particularly when routine thyroid markers do not fully explain symptoms. It can be useful when there is concern about reduced conversion into active hormone or a greater proportion being diverted into reverse T3.

Results are interpreted alongside symptom history, medication use and other relevant thyroid markers where appropriate. The test may be useful for further investigation or monitoring in more complex thyroid presentations.

Practical

Specimen requirements:

Before:
Drugs that may interfere with test results include glucocorticoids (e.g., prednisone), dopamine, lithium,
interferon-alpha, phenobarbital, phenytoin, heparin, clofibrate, carbamazepine, and colestipol. If you have
questions, please contact your healthcare practitioner.  (Do NOT discontinue any medication without consulting your practitioner.)
• Patient must fast for 12 hours prior to blood draw. (Do not eat solid food and drink only water when necessary).
• Please schedule your blood draw for Monday – Wednesday to leave enough time for the sample to reach the
laboratory before the weekend.

After:
• Write patients full name, date of birth, time and date of collection on collection tube.
• Red/grey topped SST and red topped amber transfer tube:
i. Draw the red/grey topped SST fully – must be at least 0.5ml.
ii. Mix blood sample thoroughly by gently inverting the tube 3-5 times. DO NOT SHAKE.
iii. Centrifuge the red/grey topped SST at 1000g for 15 minutes. The serum must be free of
hemolytic or red blood cells. (Centrifuge not needed, if we (at Nordic Labs) have the speciemen within 24 hours of blood draw.)
iv. Pipette all the serum from the red/grey SST into the red topped amber transfer tube.
v. Cap transfer tube tightly and place into the plastic tube holder and seal.
vi. If unable to send immediately, store in a refrigerator to keep specimen stable. DO NOT FREEZE.