In my previous blog posts “Thyroid 101” and “The Eight Blood Tests You Need to Assess Thyroid Function”, I discussed many different hormones and nutrients involved in proper thyroid function. I highly recommend you take a read through those before moving on to learning about interpreting thyroid lab tests!
When a patient begins exploring causes of their symptoms and suspects a thyroid dysfunction or a low functioning thyroid, I often see one of two things happen:
1. Their doctor will run blood work for them to assess thyroid function
Unfortunately, when this happens, they often will only run TSH and T4. And something you have probably learned from my previous articles, is that this doesn’t give us the full picture. After running TSH and T4, they either find the results are outside the reference range and they are put on medication, or the patient is told their blood work is “normal”.
OR
2. They bring their doctor a list of blood work they want run (maybe 8 specific ones) and their doctor reluctantly runs them
After having these tests run, they either find one or more of the tests comes back abnormal and are put on medication, or they are told once again that everything is “normal”.
(Often, my patients have never even seen the results and are certainly never taught about interpreting thyroid tests)
So often, the end result is either medication, or their symptoms are dismissed because their tests are “normal”
Let me tell you a little secret about “normal”.
I hate it.
A normal blood test result DOES NOT mean everything is running optimally. It simply means that you fall within the average. If your results are either considered HIGH or LOW that means they are at a level that causes symptoms in the majority of people.
My goal is not to let someone get to a level where they are almost guaranteed to be experiencing symptoms (sometimes irreversible). I practice PROACTIVE healthcare, not reactive.
Optimal, Not Just Normal
I’m going to walk you through some of the OPTIMAL blood level ranges when it comes to the lab tests typically run to assess thyroid function: TSH, T4 and T3
TSH
The range that is considered “normal” for TSH is between 0.32-4.00 mIU/L . If your levels are below 0.32 mIU/L, doctors will often assess for hypERthyroidism. If your levels are above 4.00 mIU/L, doctors will often assess for hypOthyroidism. For a gland that is so tightly regulated with feedback and negative feedback loops, this is quite a large range. Recent studies have actually shown that 95% of people with a healthy thyroid have TSH levels less than 2.5 mIU/L. (1)
I like to go one step further and aim for a level between 1.0-2.0 mIU/L for optimal thyroid function and symptom management.
Free T4
The range for fT4 that is considered “normal” is between 9-19 pmol/L. Once again, we have quite a large range! How can someone with a T4 of 19 pmol/L possibly feel the same as someone with a T4 of 9 pmol/L? When a T4 level falls above 19 pmol/L, doctors will often assess for hypERthyroidism. When levels are below 9 pmol/L, they will often assess for hypOthyroidism.
For optimal thyroid functioning and symptom control, I like to see my patients with a T4 level of between 14-18 pmol/L. But as you have probably gathered from my previous posts, T4 means nothing without its active counterpart, T3!
Free T3
This hormone is unfortunately very seldom run in a regular thyroid panel, but I see abnormalities in this hormone as one of the best indicators of symptoms in my patients. The “normal” range for fT3 is between 3.1-6.2 pmol/L. As with T4, a high level will prompt further investigation into hypERthyroidism and a low level into hypOthyroidism
I like to see my patients with a level between 5-6 pmol/L, which I find is the level they often feel their best at
T4:T3 Ratio
This isn’t really a blood test, but a simple calculation to assess how your liver/body is converting T4 into T3. This is the main reason why I like to see both a T4 and T3 level run on every blood test.
The optimal ratio of T4:T3 is 3:1, meaning 3 times as much T4 as T3. This indicates a good conversion into the active hormone, T3. If T4 is more than 3 times higher than T3, it means something is potentially interfering with the conversion – this often relates to certain nutrient deficiencies, which I briefly touch on in my “Top 5 Foods for Thyroid Support” post.
Contact Me
If you need support reviewing your blood work, let me know! I offer in-person and phone consultations for my patients. Check out my Contact Page for more information on how to get in touch, or click here to book now!