Thyroid UK
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Concerned about my low free T4 for testing

I have had low T 4 results for the past two years.. I'm extremely exhausted all the time and all I want to do is sleep.. Every great once in awhile I get a burst of energy but it doesn't last more than a day or two and I'm back to being exhausted.. I have tried to talk my doctor and increasing my thyroid medication called Synthroid but she's afraid to increase it due to the fact that I have a history of afib that was taking care of two years ago in July I went to had a cardioversion.. I have had episodes of afib that keeps coming back every great now and again and that is what she's worried about raising the Synthroid because it has a tendency to cause Afib in those who have had a history of it.. But I'm so sick and tired of being tired

2 Replies

Yes, you will be sick and tired. If you can please give us your latest blood test results with the ranges, it will enable members to comment more fully.

When you have a blood test for thyroid hormones, it should be the very earliest and fasting. You should also leave 24 hours between your last dose of Synthroid and the test and take it afterwards.

You should not have low T4 results. T4 has to be converted to the active hormone, T3 without sufficient our body cannot feel good. T3 is the active hormone required in all our receptor cells in order for our metabolism to work efficiently.

You should get a Free T4 and Free T3 blood test as FT4 and FT3 will give a better overall picture of the actual hormones in your blood.

Read about FT4 and FT3 in the following link:-

I had palpitations before and after being diagnosed and am sure it was caused by being undiagnosed and then my body didn't like levothyroxine. I haven't had palps since I stopped and switched. I switched to Natural Dessicated Thyroid Hormones first and improved but T3 resolved all symptoms. I now believe (haven't been tested) that I have a gene defect and cannot convert T4 (synthroid also known as levothyroxine) to T3..

1 like

Its the T3 thats important not T4 which is a storage hormone.


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