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Dr. B.
Dr. B., Doctor
Category: Medical
Satisfied Customers: 7827
Experience:  Physician with 8 years of experience.
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What does it mean when your T3 thyroid is high and your T4

Resolved Question:

What does it mean when your T3 thyroid is high and your T4 is low?
Submitted: 6 years ago.
Category: Medical
Expert:  Dr. B. replied 6 years ago.
Can you mention your serum tsh please?
Is this free or total t4?
Customer: replied 6 years ago.

T3 free was 4.7

T4 free .79 tsh was not run this time but has been running high in October and 4 months previous

Expert:  Dr. B. replied 6 years ago.
Dear Jacustomer,

T3 is more potent hormone than t4 ,it is not of any clinical signficance.For us,serum tsh is important .You mentioned that serum tsh level were high,this suggests that you may be having primary hypothyroidism .Low t4 or low t3(imbalance between t3 and t4) can also be seen in euthyroid sick syndrome,when a person is sick for a long time,which gets normalized with time.
Mostly all the drugs supplement t4(levothyroxine and synthryoid) but if we need a qucik action then we supplement t3 ,not so commonly prescribed.

Thanks

Customer: replied 6 years ago.

I have not been sick and heard that just knowing tsh is not helpful unless you know what T3 and T4 is which might explain why tsh is elevated

Expert:  Dr. B. replied 6 years ago.
serum tsh ,with t4 and t3 levels gives us an idea of primary or secondary thyroid problems(central from brain or from thyroid).
Elevated serum tsh with low t4 and t3 levels suggest primary hypothyroidism.
Elevated serum tsh with high t4 and t3 suggest secondary hyperthyroidism.
Feel free to ask further questions if any.

Thanks

Customer: replied 6 years ago.
if T3 is high and T4 is low is that indicative of ? I know that if tsh is elevated the brain is sensing there is not enough but what if T3 is elevated?
Expert:  Dr. B. replied 6 years ago.
T3 testing rarely is helpful in the hypothyroid patient, since it is the last test to become
abnormal. Patients can be severely hypothyroid with a high TSH and
low FT4 or FTI, but have a normal or elevated T3,so that is the reason I mentioned,it is not of no significance.
Feel free to ask further questions if any.

Thanks

Customer: replied 6 years ago.
which one T3 or T4 is that one that the body can use? One needs to be converted to the other? Thanks
Expert:  Dr. B. replied 6 years ago.
Your welcome.
T4 is converted to t3 ,body uses both but more potent form t3 gts converted from t3 from an enzyme,which is dependent on selnium and zinc,just to let you know.

Thanks

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