Are you currently taking thyroid medication and still feel unwell? Often times my patients describe suffering from thyroid symptoms despite their doctors telling them their lab work is totally normal. Why is this?


The first challenge lies in how your doctor is assessing your thyroid function. Complete thyroid hormone profiling is essential in order to measure your thyroid function while taking medication. This, in combination with monitoring symptoms of hypothyroidism, allows our naturopathic doctors to accurately determine your thyroid function in order to support your overall health. I’ve written prior blogs about how you should not rely upon testing TSH alone; you can check them out here.


The second issue with your current thyroid care stems from the fact that the conventional treatment for hypothyroidism is Synthroid or Levothyroxine. These are drugs that are made from synthetic thyroxin (T4) replacements. A healthy thyroid produces T4 and T3. Both hormones are considered ‘active’ but T3 has a much higher ability to activate your metabolism. The T4 that is produced by the thyroid needs to be converted to T3 in the liver and peripheral tissue in order to stimulate metabolic function. In prescribing T4 alone your doctor assumes that your body is able to convert you precursor thyroid hormone T4 to the more metabolically active form; T3, but often this conversion does not occur as efficiently as we’d like.


What if you are not converting T4 to T3?


Poor conversion of T4 to metabolically active T3 is often not considered in a typical hypothyroidism assessment as doctors often rely on TSH alone. This is problematic since TSH levels can remain normal despite low T3 levels, leading to persisting fatigue, hair loss, dry skin, constipation, weight gain and other symptoms associated with hypothyroidism.


What can Decrease T4 to T3 conversion?


  • Nutritional Deficiencies: Vitamins and mineral deficiencies can results in insufficient conversion of T4 to T3. Deficiencies in chromium, copper, iodine, iron, selenium, zinc, vitamin A, vitamin B2, vitamin B6 and vitamin B12 can all lead to less T3 production.


  • Medications: Prescription medications can interfere by blocking the enzymes that convert T4 to T3, decreasing production of thyroid hormones, blocking thyroid hormone at its receptor or cause causing thyroid hormones to remain bound in the blood. Birth control pills, beta-blockers, estrogen, lithium, phenytoin and steroids can all affect T3 levels.


  • Diet: A diet rich in soy products and raw cruciferous vegetables can reduce T4 to T3 conversion. I recommend that my patients avoid all non-fermented soy and ensure that they are eating predominantly cooked cruciferous vegetables.


  • Lifestyle: Alcoholism, chronic stress, obesity and diabetes can all lead to low conversion of T4 to T3.



If you suspect that you have low T3 levels, you may benefit from a complete hormone profile and assessment of basic nutrients. Our experienced Naturopathic Doctors can evaluate your symptoms and diagnostic testing to help you optimize you thyroid hormones. Book an appointment today and get on the path to beating hypothyroidism. Test, don’t guess!