What is My Correct Thyroid Dose?


Lots of members at metabolism.com with hypothyroidism ask what is their correct thyroid hormone dosage. For those who are still confused I am posting the latest Q and A addressing this issue.

Member ecchho received radioactive iodine for hyperthyroidism (over-active thyroid) and as commonly happens, developed hypothyroidism (under-active thyroid). Despite t4 levels which appear to be normal symptoms persist, so ecchho inquires about ways of dealing with this common problem.

Here is the Q and A regarding ecchho’s post:

Hi Dr. Pepper:

I had Graves disease at 23 and then had RAI at 28 and have been on synthroid for 18 years. I did try ARmour once, but I found it had too much t3 (I think the pig’s ratio of t4 to t3 is much more potent than humans) and I actually had a real hard time regulating. I don’t have a thyroid anymore, and I take 225 synthroid. i still suffer a bit with impossible weight loss (despite running, dieting, etc) and some depression that feels quite hormonal at times. My dr. brought up adding t3 last visit and tested me, and then said, oh, you don’t need any xtra t3, you seem to be converting fine.
what are the levels that the t3 should be, and is this free t3 or t3? thanks.

My reply to Ecchho’s post:

Your question regarding the correct level for thyroid functions, is frequently raised on this website. I would respond to your question with this question, ” What is the correct shoe size?” Obviously, the answer is, whatever shoe size fits best. Similarly with thyroid function, everyone has a different “comfort zone” where their body functions best. That is their “correct” thyroid hormone level. You also refer to a t4 to t3 ratio for pigs versus humans. These ratio’s are averages of several hundred individuals (human or pig)and do not apply to any particular individual. Some people function better at a t3 to t4 ratio which is higher than the average. As pointed out in my article,http://www.metabolism.com/2009/11/07/breakthrough-discovery-thyroid-hormone-therapy-part-2/ , there is recent evidence that due to genetic differences, a percentage of the population does not convert t4 to t3 efficiently and therefore are likely to require t3 supplementation when treated for hypothyroidism.

Rather than spend the money for genetic testing to discover whether the genes for conversion of t4 to t3 are abnormal, some doctors recommend simply adding an appropriate dose of t3 to the standard t4 (levothyoxine)treatment and following the patient for improvement in clinical symptoms. You might want to consider discussing this approach with your doctor.

Gary Pepper, M.D

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  • yvetteMcGuire

    I’m on a thyroid medicationLevothyroxin100MCG TAB MYLA. I’ve gained very much weight. I’m i on the correct dosage?