I will share the formulas but, please know that I'll gladly do the math for anyone who might be interested. (it took me awhile to become proficient in them)

Here's the formula to help you determine the percentage within the range for which your result may fall.

(I will use the common FreeT4 range .8 - 1.8 and a FreeT4 result of .9 as an example.)

1. Subtract the bottom of the range from the top (1.8 - .8 = 1)
2. Subtract the bottom of the range from your value (.9 - .8 = .1)
3. Divide #2 by #1 (.1 / 1 = .1) and turn the result into a percentage = 10%.

On the reference range given in the example, FreeT4 1.0 range .8-1.8 would be 10% of its range.



To help figure out a potential treatment goal, use the following formula:

(as an example, I will calculate a FreeT4 level that is 75% of the common range .8 -1.8)

1. identify the fraction that corresponds to the percentage (75% = .75)

2. subtract the bottom of the range from the top of the range (1.8 - .8 = 1.0)

3. multiply the result of #2 by the result of #1 (1.0 x .75 = .8)

4. add the result of #3 to the bottom of the range (.8 + .8 = 1.6)

A FreeT4 level that is 75% of the .8-1.8 range would be 1.6


These formulas can be used for any test result and would need to incorporate the ranges that apply to that specific test result.

So when it talks about "standard range".....is that only referring to the lab where my test was done or is that the industry standard? My T4 Free results were: 1.21 with Standard Range being 0.81-1.70.
So, using my results:
1.70-.81=.89
1.21-.81= 0.4
0.4/.89= .4494382
So, we end up with .44 or 45% of it's range? But what does this 45% represent?

Unfortunately, there's no industry standard for lab ranges. Different labs use different testing kits and the ranges apply to whatever testing kit they use.

That's why we always ask to see the reference ranges for the FreeT4 and FreeT3 tests because it seems different labs use different testing kits.

You are correct that your FreeT4 result is 45% of range.

Since most healthy people have FreeT4/T3 levels that are 60-80% of range, you can see that your level is lower than what most healthy people would have - this indicates hypothyroidism.

If you were already taking thyroid hormone replacement meds, doing this calculation with your FreeT4 level would help you know that you need a dose increase.

It's a very rare day that people have FreeT4/T3 levels below mid-range (50%) and no symptoms of hypothyroidism.

OK. Now for my T-3. My T3 Free numbers are: 2.81 with a Standard Range of 2.57-4.43. So using your formula

4.43 - 2.57 = 1.86
2.81-2.57=. - 0.240
-0.24/1.86 = -0.129
Is that correct?

You got it - your FreeT3 level is almost 13% of range - way, way lower than the type of level a healthy person would have.

I'm going to share some thyroid basics to help you understand what your levels mean:

Our thyroids produce two main hormones: T4 & T3.

T4 is our storage hormone and is converted by our thyroids and peripheral body tissues into T3, the active hormone.

The supply of T4 that is available for the body's conversion use is measured by the FreeT4 level.....and the supply of T3 that has already been converted and is available for use by every cell in the body is measured by the FreeT3 level.

Every single cell of our body needs an appropriate amount of thyroid hormone for proper function.

You can see that your body has very, very low levels of active hormone (T3).

So, not only does your low FreeT4 level mean you don't have adequate stores of T4 but, your proportionately-lower-in-the-range FreeT3 level means your thyroid and your body isn't converting T4 into T3 properly.

You might benefit from a type of thyroid hormone replacement that was the first-ever type of thyroid med ever invented - desiccated thyroid which has been around for over 100 years.

Desiccated thyroid is made from porcine thyroids and contains a larger proportion of T3 than T4 compared to human thyroids.

Since your FreeT3 level needs more "help" than your FreeT4 level, you'd be a good candidate for desiccated thyroid.

Armour is the most popular brand - here's a link to their website, if you're interested:

http://www.armourthyroid.com/default.aspx

Doctors that prescribe meds like Armour tend to be more thyroid-savvy.

That said, you might be able to find a thyroid-savvy doctor by getting contact info from local pharmacists that Rx. Armour.

Thank you so much. Carolina