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Thyroid Testing – Is TSH Enough?

Time to get a little controversial. Is TSH enough? It depends. For some, it's not and it certainly doesn’t give a complete, functional view of thyroid health.

First, quick overview of low thyroid symptoms:

-Weight gain


-Low Mood

-Dry Skin

-Bloating/Digestive Issues


-Heavy Menstruation

-Brain Fog

-Low Blood Pressure

-Muscle Aches

-Low Libido

Note - these symptoms are non-specific. Many can be explained by other medical conditions or lifestyle factors. Having a few doesn’t necessarily mean you have thyroid dysfunction, but the more symptoms, the increased likelihood of its involvement. It shows how thyroid affects so many functions in the body besides controlling our metabolic rate!

Thyroid – Gland at base of neck that secretes two thyroid hormones, in different amounts: T3 (20%) and T4 (80%)

Understanding the Full Thyroid Panel:

TSH – Released by pituitary in brain and tells thyroid gland to make T3 and T4. It’s an indirect measure of thyroid health since hormone production decreases the amount of TSH produced.

Free T4 – The ‘inactive’ thyroid pro-hormone that gets converted to T3. T4 can also be converted into reverse T3 (see below.) Synthroid, the medication for hypothyroidism, is a bio-identical version of T4 hormone.

Free T3 – The ‘active’ thyroid hormone that is converted from T4. This hormone has up to 20-fold greater affinity for thyroid receptors compared to T4. The conversion takes place within cells, mainly in the liver (so requires proper liver function), our GI tract, muscles, and heart.

Reverse T3 (rT3)– T4 can either be converted into T3 or rT3. RT3 is inactive, it’s like a metabolic reserve that doesn’t increase metabolic rate of our cells. Our body is clever – it favours the conversion to rT3 in times of stress, low calorie diets (thinks it’s starving), inflammation, nutrient deficiency, etc. with hopes of conserving energy and lowering metabolic rate during perceived 'hard' times.

TPO or TG – antibodies that target thyroid tissue, eventually impacting hormone production.


When conventional medical doctors screen for thyroid dysfunction, the standard of care is to start with TSH. To diagnose hypothyroidism, they’re looking for elevated TSH outside the reference range and this is a cost-effective approach that is backed by evidence.

However, there are different scenarios where thyroid function is sub-optimal or suppressed that can still cause someone to experience low thyroid symptoms without an elevation of TSH. It’s sort of like being stuck in a gray zone – you’re not optimal, but you’re not in a disease state.

These states have been referred to as subclinical or sub-laboratory hypothyroidism. In subclinical hypothyroidism, T4 is normal but TSH is slightly elevated. With sub-laboratory hypothyroidism, all the clinical symptoms of hypothyroidism are present, but T4 and TSH come back normal. To treat or not to treat is a very controversial topic amongst medical doctors, endocrinologists, Naturopathic Doctors and Functional Medical Practitioners.

Some key points:

1. Disease vs. Optimal Health- Many alternative health practitioners believe TSH between 1.0 and 2.0mu/L is optimal based on clinical outcomes, even though most lab reference ranges go up to 4.0mu/L. To put in perspective: if someone’s ‘baseline’ TSH was at 1.0 (but was never tested because they felt fine) and then got it tested after not feeling well and it had increased to 2.5, that’s still considered normal, even though that’s a huge increase from their baseline.

2. Thyroid antibodies (TPO and TG) - These can be elevated for a long period of time before TSH starts to go up. This is an instance where our immune system is targeting our own tissue – in this case, the thyroid gland, and thyroid hormone production is affected. In this scenario, it’d completely change my treatment plan, switching gears to more immune modulation to decrease autoimmunity.

3. Conversion Issues – If free T4 and rT3 are normal but T3 is low, this could still contribute to symptoms of low thyroid, but suggests the issue is due to poor conversion. That could be due to nutrient deficiencies (selenium, iron, Vitamin D) or issues with the peripheral tissue where conversion takes place (liver, GI tract, heart, etc.) There have also been some genetic variants discovered, where some people have a detective enzyme that is required to convert T4 to T3.

Note – someone on Synthroid could still have a conversion issue since only T4 is being provided.

4. Patient Compliance- Say someone has a full thyroid panel run, learns that their T3 is sub-optimal and that certain lifestyle changes (like daily exercise) can help improve it, it’s a real motivator. Compare this to having TSH within reference range, and being told that there’s nothing wrong.

This last point is important- the thyroid is a sensitive endocrine organ that is affected by many things in our chemically laden environment (food additives, nasty ingredients in body products, pollution, etc.), our overall health, our nutrient status, our gut health, our stress levels, and our activity level. Sometimes, it’s not about treating the thyroid itself, but the factors that affect it.

Overview of my general approach:

1. Test – full thyroid panel (TSH, rT3, free T3, free T4, and thyroid antibodies) and relevant nutrient co-factors (Vitamin D and iron) when clinically appropriate.

2. Temperature tracking – An indirect way of looking at thyroid function since it’s responsible for metabolic rate and body temperature. It’s one thing to have appropriate levels of thyroid hormones in the blood, it’s another to have cells receptive to them to increase metabolic rate. Note - there are confounding variables that affect temperature (like hormones and infection) so it must be done over time at multiple times per day.

3. Dietary tweaking – removal of refined carbohydrates and other triggers (if existing) and focus on nutrient dense foods.

4. Stress support if relevant since it suppresses thyroid function.

5. Ensure healthy hormone production and clearance – too high of estrogen will decrease free thyroid hormones in circulation since it increases the amount of carrier protein in the blood.

6. Natural dessicated thyroid (T4/T3 bioidentical hormone) if appropriate.

7/ Nutrient support – selenium, vitamin D, etc.

8. Gut support – since some conversion of T4—T3 takes place in the GI tract, and also since that’s where we absorb important nutrients

9. Herbal medicine – customizable tincture or combination extracts available

10. Lifestyle counselling – Focus on cleaning up environment: Body products, pesticides on food, fluoride in tooth paste, etc.

11. Encourage physical activity – this sensitizes thyroid receptors on cells, making them more receptive to thyroid hormones.

Most of these approaches listed above can be combined with conventional care (Synthroid) if you're still experiencing symptoms of under active thyroid with the medication.


Our healthcare system is great at detecting and treating disease but it doesn't value optimal health. Frankly, these additional tests (like free T3, rT3, antibodies, Vitamin D, etc.) are costly for the healthcare system so they can't be routinely run for everyone. It's just not realistic in a time when chronic disease is rampant, and the healthcare budget is being burdened by reactive care. Please don’t get mad at your family doctor for not running more tests. They didn't receive this functional approach during their education and they have certain guidelines they need to comply with under OHIP.

If you want to work together to optimize your thyroid health, contact here.

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