On T3-only regimen, adding in T4?

[penguinloverpatsfan]

Hi,

I have been on an exclusively T3 (Cytomel, generic, 12.5mcg/day) regimen for the past three years to treat hypothyroidism. I am an adult female. My most recent lab values have TSH and T4 at close to zero.

My doctor wants to try lowering the Cytomel and add in Synthroid.

What can I expect?

I never had a conversion problem before, just happened to go to a doc who thought it best to put me on just Cytomel.

[penguinloverpatsfan]

Thank you so much for your answer. This whole process has been really nerve-wracking and confusing, as you may imagine, and now I feel like I have some tools and knowledge to use! :) I really appreciate it!!!

[gimel]

I think it is a good idea to add some T4 to your meds; however, since you are taking a fairly low dose of T3, and since reducing the T3 would have an immediate effect, while adding T4 would take about 4 weeks to get 90% of the final effect on serum Free T4 levels, I think it would be better to just add a low dose of T4 and then slowly raise the dosage to get you up to middle of its range.  Along the way, you should re-test Free T4 and Free T3 every 4 weeks or so.  While going through this change, if there is any need to reduce Free T3,  you can reduce the T3 dosage and get a quick response.  

Before even starting on the above, I think you should be tested for Free T3 Vitamin D, B12, selenium and ferritin.  I say that because you need to know your Free T3 level, and also because hypo patients are frequently too low in the ranges for the other 4 tests.  If possible I would even get tested for adrenal function.  The best test for that is a 24 hour saliva cortisol (4 samples).  

I haven't heard of anyone that has been on T3 only for as long as you, but I don't think you need to worry about converting the T4 med to T3, even though it might take a while to get that function working normally again.  Having adequate ferritin and selenium is important for proper conversion, so that is why I suggested testing for those to establish a baseline.  

[penguinloverpatsfan]

Hi gimel,

Honestly, I don't remember precisely and I don't have any of that old labwork on hand. I do remember there being an issue with RT3 in the labs, but I don't recall the hypothyroidism ever being treated with T4 + T3 simultaneously. I've never been put on Synthroid or any similar equivalent (dessicated thyroid, etc).

I have definitely felt like I've been on a rollercoaster but didn't really consider that it could be more stable. I have depended very heavily on caffeine and that has eliminated the downs for the most part, but at the cost of literally 6+ cups of green tea and/or coffee (with espresso) per day. I also coped with it by taking the T3 at night before bed so I wouldn't get a sharp spike.

Anyway, my big concern is that I'm going to mess with my meds for nothing. I'm worried I've already lost the ability to convert T4 to T3. I mean, it's been 3 years. My labs have my T4 and TSH at nearly nothing -

T4, total: 0.2 with a reference range of 4.5-12.5
TSH: 0.1 with a ref range of 0.5-4.7

And my dose hasn't changed in at least two years (probably realistically two and a half years) so I would imagine my T4 and TSH have looked for a long time. :-/

[gimel]

Going on a T3 only medication is a somewhat extreme regimen when the patient has a big problem with Reverse T3 dominance, and has been unable to correct it by other methods.  What were the conditions that made your doctor think it best to put you on Cytomel only?  Do you have lab results from before going on the Cytomel that you can post, along with their reference ranges?  Also, what symptoms were you having before starting on the Cytomel?  Are you having any symptoms now?  

You absolutely need to add a source of T4 to your meds.  One of the functions of T4 is a storage hormone, available for conversion to T3 when needed.  Without T4, you must feel like your are on a roller coaster due to the quick effect of T3, peaking at about 3+ hours after the dose, and then dropping off over the next 3+ hours, with no T4 available to level you out.

In addition T4 also serves other important functions.  No way should your Free T4 level be left essentially at zero.  We have lots to talk about, but let's start with all this.