Low TSH

[MKitch53]

I am new to this forum. My latest blood results are TSH 0.05 (ref: 0.25-4) and T4 23 (ref: 11-22). My question is that the doctor wants me to reduce my thyroxin stating that as the T4 level comes down the TSH will go up. Am I correct in thinking that this will only happen if the T4 levels fall below the normal range ? I am confused !!

[SlowDragon Administrator]

This is very common, we often have to take "too much" T4 to feel well, then FT4 goes over range and TSH is in GP's opinion too low.

Really also need to know FT3 level to see how well you are converting before making a decision

If you reduce T4, yes TSH will rise, but FT3 will fall. If you are a poor converter this may make FT3 too low. In that case ideally you could add small amount of synthetic T3, but only an endocrinologist can prescribe this and even then it's difficult at the moment on NHS

Would also be good idea to test vitamin D, folate, B12 and ferritin. These are often too low and we need good levels to help utilise the T4

Do you know if you have high thyroid antibodies? If they have been tested. This is to diagnose if Thyroid is due to autoimmune disease, also known as Hashimoto's

[MKitch53 in reply to SlowDragon]

Thanks. I shall return to doctors for T3 level.

[greygoose]

Well, it might. And, then again, it might not. There's no guarantee what the TSH is going to do. What is certain, though, is that your FT4 will fall if you reduce your dose, and so will your FT3, making you more hypo.

But, we do need a little more detail. How much levo are you taking? How much does he want you to reduce by? Have you had your FT3 tested? Why does he want your TSH to rise, anyway?

A suppressed TSH is not a problem when on thyroid hormone replacement. It is irrelevant, and your doctor should not be dosing by the TSH. The most important number is the FT3. If that is still in range, then you aren't over-medicated.

Your FT4 is a little over-range, true, but that could be because you don't convert very well. But, if you don't test your FT4 and FT3 at the same time, you will never know. You could be one of these people that need your FT4 slightly over-range to get enough T3 to make you well. On the other hand, your FT3 could be on the floor, or it could be through the roof. But you'll never know if you don't test it. And if your doctor says thinks like : the FT3 test is of no use, is unreliable, etc. all he's doing is showing his ignorance.

But, the big question is : how do you feel on your present dose? If you feel well, then refuse to reduce it. If you feel you have hyper symptoms, try reducing a tiny amount - 12.5 mcg. If you still feel hypo, then you aren't converting or you have nutritional deficiencies. Ask him to test your vit D, vit B12, folate and ferritin.

[MKitch53 in reply to greygoose]

I have not had my T3 tested. My B12 etc is OK. I am currently on 125mcg and he wants me to reduce it to 100. I feel OK on this dose, certainly not hyper, Still occasionally get pins and needles and feel cold so am reluctant to reduce my dose. He seems to think that if my T4 drops my TSH will increase !. I might speak to him and ask for a T3 test. Thanks for your help...

[greygoose in reply to MKitch53]

Yes, of course he thinks that. It's a logical assumption. But, there's no guarantee that that will work in practice.

In any case, there is no reason to want to raise the TSH. Your TSH is fine exactly where it is. You don't need it any higher.

Pins and needles is a low B12 symptom, not a thyroid symptom. Do you have the actual numbers for your nutrient tests? Or just your doctor's opinion?

[SlowDragon Administrator]

We can get symptoms of low B12 when blood is still well within normal ranges. In part because range is probably too wide. Anything below 500 is suspicious. Also need to consider B12 in conjunction with folate levels as they both work together.

As greygoose says, get copies of your vitamin test results including ranges and post them here.

Similarly vitamin D may be in range, but too low for you.