Tirosint, atrial fib and PAC's

[montemorton]

I'm 73 y.o. so it is not a surprise that I have health challenges.  I've been on Armour Thyroid 90 mg. daily for 6 years.  In the past 20 months I've also been twice treated for hep c.  The first was in January of 2014.  The treatment was grueling and ultimately I relapsed.  

In May of 2014 I was diagnosed with atrial fib.  Had a cardiac ablation in Oct of 2014 which was helpful.  I still have  fairly frequent PAC's unless I take a low dose of sotalol (20mg twice daily).  Currently, I'm in the 8th week of a 24 week treatment with Harvoni for the hep c.  So far so good.

Recently my labs measuring free T3, free T4 and TSH have been significantly out of whack.
Free T3=573 pg/dL
Free T4=0.8 ng/dL
TSH=0.21 mcIU/mL

My endocrinologist said I was probably on too much Armour Thyroid and gave me a sample of Tirosint 75 mcg capsules.  I looked up Tirosint on the web and got a little scared as it warned that,"...Atrial fib is a common side effect associated with levothyroxine treatment in the elderly."  I don't know how safe it will be for me, admittedly an older person, and worry about PAC's which can lead to a recurrence of atrial fib.  My endocrinologist previously tried me on Synthroid 150 mcg and Synthroid 100 mcg..  Both strengths seemed not to agree with me, producing PAC's, spikes in my blood pressure and an increased pulse rate.  I went back to the Armour Thyroid each time after two days on the Synthroid.

I know that elevated Free T3 and low TSH can also be dangerous, can lead to PAC's and atrial fib..  I'm really worried and would like your opinion re: the safety of Tirosint 75 mcg.  Thank you.  Monte  

[flyingfool]

I also do not understand the wholesale switch from Armour to synthetic T4 only.  Or are you taking the Tirosint in additioni to the Armour?

If this is a wholesale switch I personally would resist the change.  If the Dr believes your FT3 are too high and you are boardering on going Hyper (which can cause rapid heart rates and A-fib) then simply lowering your Armour would make more sense.  If the Dr felt that the FT4 was too low (common with taking Armour alone) then lowering the Armour dose and adding a small dosage of T4 would make sense.

But going from a full 1.5 grain (90 mg) dose of Armour to 75 mcg of Tirosint is I believe a HUGE reduction and a complete change and potential shock to your body to adjust to.  I would not be surprised if you were slammed back into Hypo and be on a roller coaster ride which would NOT be too fun.

But I agree, we really need to know the reference ranges to get a better grasp on what is happening.

[Barb135]

What are the reference ranges for your Free T3 and Free T4?  Reference range vary lab to lab and have to come from your own report.

You should be aware that Harvoni comes with its own set of side effects.

150 mcg of Synthroid is twice the dose of 75 mcg Tirosint and 100 mcg is also considerably higher, so it's understandable how they might not have agreed with you.  

What I'm confused about is why your doctor is switching you from Armour to Tirosint in the first place, but maybe I'll understand that when I see the reference ranges for your FT3 and FT4.