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Low Free T4, "normal" Free T3?

Hi! I was hoping to get some insight on my thyroid labs.

In Sept 2015, my TSH was 3.28. This is considered "normal" by my doctor (range is .35-4.01)

In June 2016, I had the following results:

TSH - Ultrasensitive 2.50 u[IU]/mL   (range: 0.35 - 4.01 u[IU]/mL)
T3, Free 3.7 pg/mL   (range: 2.5 - 3.9 pg/mL)
T4, Free 0.78 ng/dL   (range: 0.61 - 1.37 ng/dL)
Ferritin 13 ng/mL   (range: 7 - 292 ng/mL)
Vitamin B12 304 pg/mL   (range: 211 - 911 pg/mL)
Thyroid Microsomal Ab (TPO) 0.4     (range: 0.0 - 18.3)
Anti-Thyroglobulin Antibody <0.9    (range: 0.0 - 4.0)
Calcium 9.36 mg/dL   (Range: 8.00 - 10.50 mg/dL)
Vit D - - 25 Hydroxy D total 25.6 (25.0-80.0 ng/mL)

I had the T3, Free run again in August 2016, along with an Iron panel.

My NEW Free t3 results:
3.5 pg/mL    (range: 2.5-3.9 ph/mL)

My Iron results:

Iron, Total: 83 ug/dL      (range 50-150 ug/dL)
Total Iron Binding Capacity : 318 ug/dL (range: 270-440 ug/dL)
Iron Saturation: 26%              (range 20.0 - 50.0%)

Does this mean anything to anybody? Is it weird for my Free T4 to be low, while my Free T3 is seemingly fine? My cycles would range from 14-22 days. On the pill, I was more like 17-24 days. Better, but still not great. I stopped taking it, because I don't see the point. I have also gained 15+lbs, and while I've managed to lose about 5lbs, that's with following a fairly strict diet and working out 5-6 times a week.

I did start supplementing vit d and vit b this week. We'll see if that brings my numbers up.
1 Responses
Avatar universal
In the words of a good thyroid doctor, "The free T3 is not as helpful in untreated persons as the free T4 because in the light of a rather low FT4 the body will convert more T4 to T3 to maintain thyroid effect as well as is possible. So the person with a rather low FT4 and high-in-range FT3 may still be hypothyroid. However, if the FT4 is below 1.3 and the FT3 is also rather low, say below 3.4 (range 2 to 4.4 at LabCorp) then its likely that hypothyroidism is the cause of a person's symptoms."  

So that is one possibility for your having hypo symptoms with those test results.  In addition have a look at the information about pooling of T3 in the blood and not getting into cells, as discussed in this link .


Your very low ferritin result is a potential cause for T3 not getting into your cells where needed.  Ferritin should be 70-100.  D should be above 50 and B12 in the upper end of its range.  You probably should get all three optimized and then see what your all your levels are.  At that time, as an indicator of tissue thyroid hormone levels, it would be good to get tested for Reverse T3 along with Free T4 and Free T3,  and also test for morning serum cortisol.  
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