Reverse T3 (rT3)
Reverse T3 (rT3) is an inactive form of T3 that is produced in the body particularly during periods of stress. Cortisol inhibits the conversion of T4 to T3 and more rT3 is produced. rT3 blocks the T3 receptors.

High rT3 levels are seen in leptin resistance, inflammation (NF kappa-B), dieting, nutrient deficiencies such as low iron, selenium, zinc, chromium, Vit B6 and B12, Vit D and iodine, low testosterone, low human growth hormone, Insulin dependent Diabetes, Pain, Stress, environmental toxins, free radical load, haemorrhagic shock, Liver disease, Kidney disease, Severe or systemic illness, severe injury, Surgery, Toxic metal exposure,  fibromyalgia, chronic fatigue syndrome (CFS), and Wilson’s Thyroid Syndrome. Measurement of rT3 is also valuable in identifying sick euthyroid syndrome where active T3 is within normal range and rT3 is elevated. rT3 should be less than 250.

Serum (Blood Draw) or Blood Spot

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