I recently had a routine blood test at the request of the GP (TSH and FT4) and I also did a private test so that I had a result for FT3 as well. Both results showed a suppressed TSH but both FT4 and FT3 are within the normal range:
GP tests:
TSH: 0.06 [0.27 - 4.2]
FT4: 19.5 [11.4 - 21.4]
Private tests (monitor my health):
TSH: 0.06 [0.27 - 4.2]
FT4: 19.4 [12 - 22]
FT3: 4.8 [3.1 - 6.8]
I have been asked to make an appointment to discuss the results. I feel better now than I have at any time since my diagnosis and want to be able to argue effectively to stay on my current medication (125mcg/150mcg levothyroxine on alternate days). Any comments or advice would be very welcome.
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Wong64
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If you feel better on this dose there is no reason to change anything.
The TSH was originally introduced to be used as a diagnostic tool help diagnose a case of hypothyroidism and it was never intended to be used as measure of anything once on any form of thyroid hormone replacement.
Your T4 is currently around 74% and your T3 - the most important of all 3 numbers at around 46% through the range - and this shows no signs of over medication.
In fact most people feel at their best when T4 is in the top quadrant which you just are, as the higher the T4 the logic is the higher the T3.
It is too low a level of T3 for you that gives you the symptoms of hypothyroidism just as too high a level of T3 may give your symptoms of over medication, sometimes referred to as hyper type symptoms.
Obviously having Hashimoto's does throw a spanner in the works as you are liable to experience erratic thyroid production as your immune system attacks the thyroid causing transient higher levels of hormones but after the attack likely to experience lower thyroid hormone production as the gland becomes disabled and damaged.
The accepted conversion ratio when on T4 monotherapy is 1 / 3.50 - 4.50 - T3 / T4 and most people people better coming in at around 4 or under : so to find your conversion ratio you simply divide your T3 into your T4 and I'm getting 4.04 so good conversion of T4 into T3.
You might like to keep an eye also on ferritin, folate, B12 and vitamin D as these essential core strength vitamins and minerals need to be maintained at optimal levels to assist T4 into T3 conversion.
As Pennyannie says, if you feel good on your current dose there is no need to change it.
Your GP may not like your suppressed TSH but once on thyroid hormone replacement it's not the most important result, it's not a thyroid hormone, it's a pituitary hormone. The thyroid hormones are FT4 and FT3 and these tell us our thyroid status. Your FT4 is well within it's range and if anything, your FT3 could be higher but if you are happy where it is then there's nothing to worry about.
If your GP wants to reduce your dose of Levo, produce the following to support you in staying on your current dose:
Dr Toft, past president of the British Thyroid Association and leading endocrinologist, states in Pulse Magazine (the professional publication for doctors):
"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l. In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l. Most patients will feel well in that circumstance. But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l. This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l).*"
*He recently confirmed, during a public meeting, that this applies to Free T3 as well as Total T3.
You can obtain a copy of the article by emailing Dionne at
tukadmin@thyroiduk.org
print it and highlight question 6 to show your doctor.
You can see from that quote that as long as FT3 is within range you can go even higher with your FT4 and it's OK for TSH to be suppressed.
Thank you for the information about Dr Toft's article. I may be borrowing trouble but I'll feel much better going in armed with this information than without. I'm not actually getting to see a GP, just a clinician (whatever that may be - nurse practitioner?) Anyway, because of that I'm unsure whether they might be less flexible about deviating from the usual narrative where TSH rules (even tho it's a pituitary hormone).
Were both test done as early as possible in morning before eating or drinking anything other than water and last dose levothyroxine 24 hours before test
Do you always get same brand levothyroxine
When were vitamin D, folate, ferritin and B12 last tested
Do you currently take any vitamin supplements
Low vitamins can lower TSH
So if GP is difficult about staying on current dose levothyroxine
Request vitamin levels are tested, or test yourself via Medichecks, Blue Horizon or Thriva
Ft3 is nowhere near top of range, so if you feel well you don’t need to reduce levothyroxine
Interestingly, patients with a serum TSH below the reference range, but not suppressed (0.04–0.4 mU/liter), had no increased risk of cardiovascular disease, dysrhythmias, or fractures.
It is unfortunate that we did not have access to serum free T4 concentrations in these patients to ascertain whether they were above or within the laboratory reference range. However, our data indicate that it may be safe for patients to be on a dose of T4 that results in a low serum TSH concentration, as long as it is not suppressed at less than 0.03 mU/liter. Many patients report that they prefer such T4 doses (9, 10). Figure 2 indicates that the best outcomes appear to be associated with having a TSH within the lower end of the reference range.
Thank you for your help @SlowDragon. I took the home test at 8am, but the one for the GP was 11.30am (earliest I could get). I only drank water and there was at least 24 hours since my last dose of levo. I always get the same brand of meds. My vitamin D and B12, ferritin and folate haven't been tested in a couple of years. Thanks for the link to the paper showing no increase in risk of cardiovascular disease when TSH low but not suppressed - very reassuring.
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