Thyroid UK
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Help with results please. Extra levo needed?

Hi I'm underactive and have been for the last 4 years. Lately, my tsh has started to creep up a bit again, so GP has increased my dose to 125mcg levothyroxine. My latest result has come back as tsh 1.6 and t3 1.6. I'm afraid i don't know the range. The GP has left it up to me as to whether I want to increase my dose further, as she likes to see tsh at about 0.5. Just looking for some advice please? I'm still feeling very tired and sluggish, but don't want to end up being suppressed too much.

2 Replies

Actually, it doesn't matter how low the TSH gets. It isn't a thyroid hormone. The important number is the FT4, but without the range, the number is meaningless. But, if your doctor wants to increase your dose, go for it! It can be very hard to get a needed increase sometimes.

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As Greygoose says, a suppressed TSH isn't a problem in itself, though many GPs (and rather too many endocrinologists) don't seem to understand why it isn't.

Here's why they think it is a problem - and why it isn't.

There are 2 main thyroid hormones. They are T4 and T3.

A healthy thyroid gland makes T4. But T3 is the active thyroid hormone - the one that acts at a cellular level. Your body makes T3 from T4 (using iron, Vit D, selenium amongst other things) and a lot of the T3-making happens in the liver (yes, the liver. Not the thyroid). Your pituitary gland - a tiny little gland in your brain - monitors thyroid hormone levels in your body. A healthy thyroid gland pumps out T4 in response to what the pituitary gland tells it to do. If the pituitary gland thinks there's enough T4, it lessens the signal. If it thinks you need more, it heightens the signal. That signal is Thyroid Stimulating Hormone - TSH.

In people who are hyperthyroid, the thyroid pumps out way too much T4. Because there's lots of it sloshing around in the blood, the pituitary gland shuts off the TSH signal - it tends to be very low, or what people call "suppressed". If you were to get your hands on typical blood test results from a hyperthyroid person, you'd typically see a suppressed TSH, an over the top of the lab range Free T4 result and an over the top of range Free T3 result.

In people who are hypothyroid, the thyroid doesn't pump out enough T4. The pituitary gland (unless the pituitary gland itself is faulty, and that's not as uncommon as many doctors realise) sends out a heightened signal - raised TSH - in an attempt to get the thyroid to make T4. It usually doesn't work, but it tries really hard. In addition, the hypothyroid person, once they've been hypothyroid for a while and remain untreated, will have a very low Free T4 blood test result and an a very low Free T3 result. But when a hypothyroid patient takes levothyroxine (synthetic T4) the pituitary breathes a sigh of relief and stops flogging the thyroid - the TSH drops. But if the levothyroxine dose isn't high enough, the thyroid doesn't get the message that it needs to make up the shortfall. The TSH is suppressed but there isn't enough T4 to go around!

Ideally, doctors should be able to order TSH, FT4 and FT3 lab tests but over the years doctors and laboratories have convinced themselves that the only test needed is TSH. But if you stick around and read posts here, you'll see that many people have suppressed TSHs but their FT4 and FT3 results are low in range. Those people can't possibly be overmedicated because if they were, their FT4 and FT3 results would be over the top of their lab ranges.

Unfortunately, doctors see their suppressed TSHs and panic. They speak darkly of heart problems and osteoporosis. Why? Well, people with untreated hyperthyroidism (overactive thyroids) *are* at risk of heart problems and osteoporosis. But it's not because their TSHs are suppressed. It's because too much thyroid hormone is sloshing about in their systems.

If your TSH is suppressed but there is a lack of thyroid hormone sloshing about in your system, you have undertreated hypothyroidism. You need more thyroid hormone, never mind that the TSH is suppressed. It's best if you can to persuade your doctor to test FT4 and FT3 to see what's really going on. Failing that, you can get private blood tests done to find out for yourself.

Hope that helps x


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