Avatar universal

NP Thyroid and Cytomel

So, to follow up on what has been a real battle.  My out of network provider wanted to start me on Armour of 15 3 x a day 5 days and 15 4 x 2 days, I did the math, like Gimel and others here and it did not add up.  We argued extensively about starting at 90. Compounding the t3 was not possible in South Carolina, but I did speak to a Dr. Hameed in Raleigh, who also said starting dose per my current regime of 50 mcg t4  4 days, 75 mcg 3 days and 25 Cytomel daily was 90.
And after talking to various pharmacists and the other compounding pharmacists, I went back to argue the correct dosage.  In the midst of all this, my primary in Florida quit and the new Dr. refused to even discuss calling in a script, having never seen me.  To say I have been stressed, is an understatement. Finally, the out of network provider complied and wrote for NP Thyroid 90 with addition 5 mcg of Cytomel.  I don't have the Cytomel yet.  Compounding the T3 is expensive, at 25 mcg daily.  So, after all the saga, am I on the right path and the right dosage? I sincerely trust this forum more then doctors, lol
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Avatar universal
Starting from the beginning, one grain (60) mg of NP Thyroid contains 39 mcg of T4 plus 9 mcg of T4.  So your new dose of 90 mg of NP Thyroid and 5 mcg of T3 daily is a total of 58.5 mg of T4 ( 39 + 19.5) and 18.5 of T3 (9 + 4.5 + 5 =18.5)  There is nothing there for a doctor or anyone else to argue with.  Those are just the facts.  

The problem starts with trying to equate a combo dose of T4/T3 to  another.   The best way to compare is to convert it to equivalent T4.  This is done by multiplying the T3 amount by 3, because the ATA/AACE Guidelines , on page 1002, righthand column, second paragraph, says that the ratio for the pharmalogical equivalent of T3 to T4 is 3 to 1.  Here is a link from which you can find the info and copy the page for the doctor.


IF we take your old medications doses the (50 x 4 days) + (75 x 3 days) equals 425 mcg weekly, or about 61 mcg daily of T4.   If we use the daily dose of T3 (25 mcg) and multiply by 3 to get the  equivalent in T4, that is 75 mcg.  So the total amount of your old daily dose, expressed in T4, is 61 + 75 = 136.  

Now to compare, your new med dose of 90 mg of NP Thyroid we need to convert to T4 equivalent.  As stated, the 90 mg of NP Thyroid plus 5 mcg of T3 daily is a total of 58.5 mg of T4 ( 39 + 19.5) and 18.5 of T3 (9 + 4.5 + 5 =18.5).   Converting to equivalent T4, you would add the 59.5 mcg of T4 plus 55.5 mcg equivalent T4,  (3 times the 18.5 mcg of T3).  This totals 58.5 plus 55.5 which is 114 mcg of equivalent T4.  

So your old dose was actually more than your new dose by the equivalent of 22 mcg of T4 (136 minus 114).   The reason there is so much confusion about all this is that conversion tables show that 60 mg of NDT, like NP Thyroid, is equivalent to 100 mcg of T4.  This is wrong.   For that to be correct, instead of the recommended factor of 3, you would have to multiply the T3 portion by almost 7, for it to be equal to 100 mcg of T4 (39 + 7 times 9 = 100).   Conversion tables also show that 25 mcg of T3 is equal to 100 mcg of T4.  That also is incorrect according to the link.  For it to be true the conversion would have to be 4  (4 x 25 = 100), instead of the Guidelines factor of 3.

You might be able to use this info to convince your doctor that your new dose is less than old dose and you needed to increase, not decrease.  Your old dose was close to 120 mg of NDT, so you need to move up to 2 1/4 or 2 1/2.    An important note here:  Always delay your morning dose of thyroid med until after the blood draw for thyroid tests, as recommended also in the link, page 999, lefthand column, 2nd paragraph.
Helpful - 0
You can not imagine the struggle it was just to get the 90 mg.  That it is less then I need is terrible news, and is going to be a fight.  Frankly, I am exhausted.  I have been steady gaining, feeling poorly to begin with.  I was hoping a change would be good, because I have felt bad a long time, with this current regime of Levoxyl and Cytomel.
As the pharmacy is still unable to get the 5 mcg of  Cytomel, I won't start the NP until I know I have that. I now don't know if I should start the NP at a all?
I will send all of this to the prescribing ARNP.  Who knows what will happen from there?
  I appreciate all the info, Gimel.
I am terrible with math, so the numbers are difficult for me to calculate.  Apparently, for her, too.  Especially using a flawed chart.  I just remember how I felt in May.  Reducing me to 50 t4 nearly put me in the hospital.  I was so sick.
Avatar universal
Sorry, I noticed an error in the 5th paragraph.

"Converting to equivalent T4, you would add the 59.5 mcg "

It should be 58.5 mcg there , consistent with the following line.
Helpful - 0
1756321 tn?1547095325
Gimel, NP thyroid it states 38 mcg of T4 and 9 mcg of T3. I hate maths so glad to not be working that out lol.

I was not absorbing Armour but absorbing synthetic so I searched for how each was absorbed and found this info.

Excerpts from the book: Thyroid Diseases: Clinical Fundamentals and Therapy by Fabrizio Monaco, Maria A. Satta, Brahm Shapiro, Luigi Troncone...

"There is some differences in the rate of absorption between animal and synthetic preparations. After a single oral dose of synthetic L-T4, the absorption is approximately 70 - 80%, 20 - 30% being recovered in the stool.  It is absorbed rapidly, mainly in the distal small bowel, reaching maximum plasma levels in 2 to 4 hours."

"Variability of absorption also occurs with desiccated thyroid, dependent on proteolytic enzymes of the gastrointestinal tract. Since desiccated thyroid and thyroglobulin preparations contains T4 and T3 incorporated into thyroglobulin, to release thyroid hormone the crude preparations must be hydrolyzed by gastrointestinal proteolytic enzymes, which indirectly influence the absorption of T4 and T3."
Helpful - 0
Goodness I wish I understood all of that, mostly because it really helps with your own care if you understand how things work. I can only retain just so much. Oh well next lifetime medical school
Avatar universal
Thanks Red_Star, I assumed that it was exactly the same as most other NDT type meds.  Instead of going from the old dose of 136 mcg of equivalent T4 down to 114 mcg,  the new dose would be 112.5. mcg.

Also, thanks for the info on absorption.  I had wondered about the actual amount.  So what is the estimated absorption of T3?  
Helpful - 0
Yeah, no worries. :) No mention of T3 in regards to absorption.
Avatar universal
All I know is my wife’s experience.

She tried Armour for a couple years I would guess. And finally had to add T4 in addition to the Armour. That still didnt make her feel well.

In an attempt to change, she went back (seceral hears ago she was on dual synthetic T4 and T3). To a combination of synthetic T4 and T3.

She has responded well to even what the “equivalent” dosage of what she was on with the combo Armour and T4.

I can only assume she responded better due to absorption issues.

As far as the OP.

I am not sure of the blood labs and rhe history to have gotten to the dosage and now combination of NP and T3.

However I would recommend only adding a second medication only after one of the blood labs has gotten to about the recommended level and the other is not optimized yet.

Seems to me you may be jumping into NDT before having fully explored the dosage changes that seem to be proposed by a confused Dr.
Helpful - 0
Yes the absorption issues! The maths doesn't take absorption into account.
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