I am going nuts trying to figure out how to calculate my FT3 to FT4 ratio, because the results are reported in different units of measure:
FT41.6 ng/mL
(0.60 - 1.70 ng/mL)
FT3 2.3 pg/mL
(2.57 - 4.43 pg/mL)
When I tried getting them both into nanograms, I ended up with a ratio of 0.0014375.
When I converted the ng measure into pg, I got the same result. The ratios I have seen discussed in Journal articles tend to be in whole numbers. Need a math wizard to explain this to me. Thanks.
You will have problems!
Most discussion of T4:T3 ratio here is based on molar measurements (rather than mass).
That is, something like picomoles per millilitre. Most of the world outside the USA uses molar measurements.
Also, are you sure that your FT4 measurement is in ng/mL? Rather than ng/dL.
Isn't what's important here is that your FT3 is LOW - below range whilst your FT4 is high in range.
You need some T3 don't you? Are you under an Endocrinologist?
Do you still work out? I've read on this forum that strenuous exercise depletes T3.
Gentle exercise only such as walking, swimming (you bowl which is gentle? )
I'm in an HMO. In the test results report, my PCP (primary care provider - she is in (Internal Medicine) wrote on Oct. 9:
Comments from the doctor's office
Hello,
Your free T3 level was slightly low, but remaining labs are normal.
I recommend we continue the current dose of levothyroxine and repeat labs in 4-6 weeks
And yes, you are right. I am convinced I need some T3, but don't know how likely it is that my wishes will be honored. She has already had all kinds of things tested to rule out other causes of my persistent hypo symptoms, including cortisol and sex hormones. I asked for Vitamin B12, Folate, and Vitamin D to be tested, too, and they are all within normal range.
Your Free T3 was LOW - below range.
It needs addressing now - also you have symptoms.
Any other doctor you can see ?
Preferably a Specialist / Endocrinologist?
What's H M O ?
I can ask for referral to Endo, which she is likely to grant if she is afraid to prescribe T3 because there are no practice guidelines telling her it is OK to do so. So that's Plan B. Plan C is to go outside the HMO (Health Maintenance Organization). An HMO operates on the concept of keeping you well. All kinds of health reminders to get a flu shot, you're due for a Mammogram, etc. So although in fee-for-service health plans, preventive care is often extra, in an HMO it is all included.
VocalEK
Why do you need a ratio?
Is it to do with T4 to T3 conversion and seeing if you would benefit from the addition of T3 to Levo?
If so, you don't need the ratio. You can see from your results.
Your FT4 is 90% through it's range.
Your FT3 is below range (I think it's minus 14%)
Your doctor would have to be blind to not see that your conversion is not only poor but non-existent.
Have you asked her to trial T3 or NDT ? With HMO you should have no difficulty.
It doesn't matter. Nor does the ratio (most likely)., What matters is the distance through the range. You can see that your free T3 is under range and your free t4 is over 90% of the way through the range, so what more do you need to know? Poor conversion is obvious.
FT4 = 1.6 ng/dL = 20.6 pmol/L unitslab.com/node/121
FT3 = 2.3 pg/mL = 3.5 pmol/L unitslab.com/node/120
FT4/FT3 is over 5.8
Low TSH, FT4 & Ft3 
Diarrhoea, high ft3 low ft4.
Blood test - fT3 fT4 and TSH
TSH/FT3/FT4 Test Results 
