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Calculating your T3 ratio depends on having two very important values, your T3 levels and your Reverse T3 levels.

As a person who has thyroid disease or who suspects thyroid disease, you probably have heard about  some of the more advanced tests now being used to evaluated thyroid function. Tests like reverse T3, Free T3, Total T3 and Sex Hormone Binding Globulin.  But you should also be aware of the calculation (not lab test) of the T3:reverse T3 ratio or the Free T3:reverse T3 ratio. This ratio provides information about your thyroid and should be calculated whenever you have thyroid symptoms but a normal TSH. There are additional reasons for these calculations as you see below.


Why you want to calculate your T3 Reverse T3 ratio

  • This ratio helps you understand how well your body is converting T4 into T3 – read more about this here if you haven’t heard about this conversion process.
  • It helps you understand if your current medication and dose are working for you – If your medication is working then your free T3 should be normal and your reverse T3 should be low/normal. If your levels are not improving with thyroid medication here are 10 reasons why you thyroid medication stopped working.
  • It helps put your symptoms into context – Many people find that they are confused because of their so-called ‘normal’ lab tests and this T3: reverse T3 ratio can explain how you can have a normal TSH but still suffer with low Thyroid symptoms. If your Reverse T3 is elevated you will need to further testing to uncover why you have high reverse T3 levels.
  • It can help you understand other factors which need consideration – Do you have symptoms of inflammation? do you have a leaky gut or SIBO or other GI problems? Some of the factors such as gut health and inflammation can all influence this ratio. If your ratio is off then it can help direct you to other problems which may be influencing your thyroid.
  • It’s one of the most sensitive measures of thyroid function – the difference between your free T3 and your reverse T3 can identify thyroid dysfunction very early on and becomes abnormal long before other measures of thyroid function such as TSH and free T4.


Need Your Thyroid Hormone ratio? This calculator Can Calculate It For You!

Enter your lab results in the fields below and my calculator will provide you with your T3/rT3 ratio. Select the correct unit of measurement recorded on your results sheet and click submit to see the result.


Calculate Your T3 Reverse T3 Ratio Levels Using The Calculator You See Below

T3/FT3 pmol/Lpg/mLpg/dLng/dLug/LRT3pmol/Lnmol/Lpmol/mLug/L


Why Calculating Your T3/rT3 Ratio is Important

The normal thyroid gland produces T4 and T3, and some rT3.Reverse T3 is not a problem in every patient  suffering with Thyroid disease. Knowing what your T3/rT3 levels are can be a great way of monitoring your Thryoid function. Being able to calculate your T3/rT3 Ratio allows you to determine whether your hypothyroidism and the symptoms that go along with it (Fatigue, Brain fog, weight gain, hair loss, bone health, constipation-IBS, heart rate, body temperature) is caused by an excess amount of reverse T3 hormone.


To Calculate your rT3 ratio You Will Need The Following Thyroid markers

  1. T3 (Total) or
  2. Free T3
  3. Reverse T3 (rT3)


Here Are Some Common Causes for a Low FT3/rT3 ratio or Low T3/rT3 ratio:

  • Anorexia
  • Low Ferritin (iron anemia)
  • Leptin Resistance
  • Nutrient deficiencies such as low iron, selenium, zinc, chromium, Vit B6 and B12, Vit D
  • Environmental Toxins
  • Liver Disease or Toxic overload, Liver congestion
  • Heavy Metals
  • Low Testosterone
  • Surgery
  • Certain Foods
  • High cortisol, this disturbs the balance of the thyroid hormones
  • Low cortisol, this again disturbs the balance of the thyroid hormones
  • Blood Sugar problems/ Insulin Resistance/Diabetes
  • Inflammation (NF kappa-B)
  • Medications- Some medication can elevate your Reverse T3. Medications such as propylthiouracil, ipodate, propranolol, amiodarone, dexamethasone, and the anesthetic agent halothane.
  • Some Medications can Lower your Reverse T3. Medications such as Dilantin decreases rT3 due to the displacement from thyroxine-binding globulin, which causes increased rT3 clearance.


There Is Much More to Stabilizing Thyroid Function- Then Replacing Hormones

If you have been struggling with Thyroid problems then you know how frustrating it when your doctor only believes in (Synthroid) T4 or T3 replacement. Some physicians believe treatment of hypothyroidism is simply a matter of  prescribing the patient Synthroid and telling them to come back in 3 or 6 months. Well…. for an overwhelming majority of men and woman this doesn’t cut it. There are many causes behind poor thyroid function and I have created numerous videos, articles and newsletters to help educate the public about these matters. I encourage you to read these articles on my website.


Other articles about Reverse T3 Readers Found Helpful.


Our Personal Thyroid Treatment Program is a great place to start

The Personal Program Thyroid Recovery Program is a Natural Treatment for Low Thyroid function, Hypothyroidism, Hyperthyroidism and Hashimoto’s disease. It is a comprehensive program that leaves no stone left un-turned. Our office offers the most comprehensive program to target thyroid disease at the root cause. We utilize targeted nutritional supplements based on Functional Nutrigenomic testing, Meal planning, Food recipes, Dietary counseling, Hormone and endocrine support, bio-identical hormone replacement, and lifestyle guidance. 

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Each person suffering with Thyroid symptoms problem has a different set of mechanisms or causes.  Our office will customize a Thyroid Restoration Program based on your testing and tailored to your individual needs.