Are you talking about only a 5 mcg dose of Cytomel, or the addition of 5 mcg to a prior dose?
In the untreated state, our bodies are used to a continuous low flow of thyroid hormone from the gland. When taking a significant dose of thyroid med all at once, studies have shown that would tend to suppress TSH for most of the day. Yes, each individual is different regarding their equilibrium among TSH Free T4 and Free T3, but if you are talking about only a 5 mcg total dose, then I would not expect that to cause TSH to be suppressed below range.
The 5 mcg of Cytomel should not cause that. TSH is affected by so many things, including time of day when tested, test repeatability, etc.
Most hypothyroid patients taking thyroid med adequate to relieve hypo symptoms find that their TSH is suppressed below range. That has been shown to result from taking the med in only one or two doses. So, instead of what many doctors think, a suppressed TSH during treatment does not mean hyperthyroidism unless there are hyper symptoms due to excessive levels of Free T4 and Free T3. Interestingly there is a recent study that quantified for the first time the effect of Free T3 on symptoms. The authors concluded, "Hypothyroid symptom relief was associated with both a T4 dose giving TSH-suppression below the lower reference limit and FT3 elevated further into the upper half of its reference range".
Are you still having hypo symptoms? What are your Free T4 and Free T3 levels and reference ranges shown on the lab report?
I suspect that if she was already taking 125 mcgs synthroid (T4), it was not enough yet to suppress TSH. But she was probably on the edge of suppression. The additon of the 5 mcg of T3 may have been just enough to cause suppression. It seems some people and the pituitary is very sensitive to T3. And once the pituitary "saw" the T3 it concluded that no more TSH was needed to turn on the thyroid gland.
It would be nice to know what her Free T4 and Free T3 levels were prior to, and just after her TSH went from 4 to suppressed!
You need to get the doctor to test for Free T3, not Total T3. Only the small portion of Total T3 that is not bound to protein (thus called Free T3) is biologically active. Your thyroid status is a reflection of your TISSUE T3 EFFECT. To achieve adequate TISSUE T3 EFFECT you need for your Free T3 to be in the upper part of its range. Based on your Total T3 being only 34% of its range, it appears you need to increase your T3 med. Along with that you can reduce your T4 med since Free T4 is higher than needed. So I would talk to your doctor about a decrease in T4 coupled with an increase in your T3 med. There was a recent study that quantified for the first time the effect of Free T3 level on the incidence of hypo symptoms. The authors concluded that, "Hypothyroid symptom relief was associated with both a T4 dose giving TSH-suppression below the lower reference limit and FT3 elevated further into the upper half of its reference range". Following is a link to that study, which you can use to help persuade your doctor of the need to change your meds.
In addition, Hypothyroid patients are frequently deficient in other areas the affect the response to thyroid hormone, such as cortisol, Reverse T3 (RT3), Vitamin D, B12 and ferritin. If not tested for those you should also request the doctor to order those tests as well. If you need further info to persuade your doctor, use the one page Overview of the paper on Diagnosis and Treatment of Hypothyroidism: A Patient's Perspective. You will find that by clicking on my name and then scrolling down to my Journal.
Sorry, I just saw your last post, which came up while I was entering my response to your prior message. From the results on the 2 grains of Armour resulted in a Free T4 of ..97, which is only 5% of its rnage, which is much too low. Your Free T3 was only at 32% of its range which is also too low. The Endo apparently only looked at the TSH and decided you were hyper. That is incorrect. I explained above why TSH should not be used to determine a hypo patient's med dosage because of the suppression that occurs with once or twice daily significant doses of thyroid med.
In addition your Vitamin D is way too low. It should be at least 50 ng/mL. Your B12 is higher than needed so you could reduce your B12 supplement. Your ferritin is also way too low. It should be at least 100 so you need a good iron supplement like Vitron C to optimize. Vitamin D and ferritin are very important for you.
Based on what the doctor has done so far, I think you need to find a good thyroid doctor that will treat clinically, by adjusting your Free T4 and Free T3 levels as needed to relieve hypothyroid symptoms, without being influenced by resultant TSH levels. Have we tried to help you find a good thyroid doctor that is close enough for you to go there?
It is relatively common for a person on Armour to be very low Free T4. But as pointed out above, your Free T3 is still not up high enough.
I would recommend you continue to increase your dose of Armour until you start to feel well. And then you may want to add in T4 medication (synthroid) dose IN ADDITION to the Armour to bring up your FT4 level.
Or it might be easier to talk your Dr into adding in synthroid now IN ADDITION to keeping your Armour thyroid dose, and keep raising the T4 dose up until you either feel well, and your FT4 level gets to 50% of the range. If you still don't feel well then. THEN add in further Armour dose.
Some people do better on dual synthetic of synthroid and (T4) and Cytomel (T3) rather than Armour. Both my wife and my daughter seem to do better on the dual synthetic rather than Armour and syhthroid together.
Typically women do not do well with T4 only while many men respond well. Most women tend to do better on Armour plus if needed T4 medication. But it is all individual and at the end of the day. What combination works for any one person doesn't matter. As long as they can find a combination of medications and dosages that work FOR THEM!
I'm sorry to hear that your not feeling up to par. I've said it before, but two grains of Armour (120 mg, contains 76 mcg T4 and 18 mcg T3) is a relatively low dose and in fact many people are distinctly hypothyroid on 2 grains. So most likely your problems are due to you're simply not getting enough thyroid med.
Re your question of the effect of 5 mcg T3 on TSH. I think the reason your TSH drops low is because you were using fast acting Cytomel. After you take it, you get a blood level spike of T3 for several hours and that high spike is what lowers your TSH. Personally I am using compounded slow release T3, which supposedly releases the T3 over 12 hours, so your blood T3 level does not spike nearly as high. For comparison, my TSH on 100 T4 + 5 T3 was 2.29, and on 100 T4 + 15 T3 was 1.52.
Armour comes in 1/4 grain (15 mg) sizes. I think your next move would be to move to 2 1/4 or 2 1/2 grains of Armour, but your TSH will be even more depressed and it will depend if your new endo understands that you do not have to worry about that.
2 1/4 grain = 135 mg Armour (contains 86 mcg T4 and 20 mcg T3).
2 1/2 grain = 150 mg Armour (contains 95 mcg T4 and 22.5 mcg T3).
I think that you would find either one would give you a significant improvement.
Just wanted to make sure you saw my post right before flyingfool's post.