I had my TSH blood test with the NHS on Oct. 20. It was 0.98 miu/L range (0.35 - 4.78).
3 weeks later, I did a Medichecks test so I could see my T3 and T4. It shows a completely different picture, with my TSH at 3.53 (see results in image above).
How do I know which result to trust? Is the finger-prick blood test maybe not as accurate?
I’ve had Medichecks result which was well into the normal range and the NHS result showed I was quite Hypothyroid. As I was newly on Thyroxine and being titrated up my GP threw out the Medichecks result quite rightly. I should have complained and got my money back but I didnt understand it all at the time last year. Very disappointing x
Were both tests done early as possible in morning before eating or drinking anything other than water and last dose levothyroxine 24 hours before test?
TSH varies significantly depending on what time of day tested. Very important to always test at same time of day
Do you have autoimmune thyroid disease also called Hashimoto’s diagnosed by high thyroid antibodies?
Autoimmune thyroid disease causes rapid changes in thyroid levels
Ft4 and Ft3 are both very low
Ft4 is only 34% through range
Ft3 only 12% through range
Helpful calculator for working out percentage through range
Ask GP for 25mcg dose increase in levothyroxine
Essential to regularly retest vitamin D, folate,, ferritin and B12
Low Ft3 frequently causes low stomach acid and this leads to low vitamin levels
What vitamin supplements are you currently taking
Yes, both tests were 24hrs after last dose of levo. Both were in the morning. The NHS one at about 9am, the Medichecks around 7:30am. Yes, I have Hashimotos. Are you saying I should ask for an increase in levothyroxine even if the NHS test of TSH<1 is accurate?
If the Medichecks test isn't accurate, then I may still know nothing about my actual Ft3...
Vitamin supplements: vit E, C, B complex, D, inositol, selenium, sometimes zinc, a little calcium.
My most recent tests for D and B12 and folate were good. My ferritin is low (last test was 29 in range 15-250).
Low Ft4 and very low Ft3 shows you are under medicated
How much levothyroxine are you currently taking?
When were vitamin levels last tested
What vitamin supplements are you currently taking
I'm currently on 75mcg of levo. Last vitamin level tests were June this year (B12 was 724 in range 200-900, and D was 90 in range 75-200).
I updated my message above with list of supplements. But adding here too:
Vitamin supplements: vit E, C, B complex, D, inositol, selenium, sometimes zinc, a little calcium.
Did you remember to stop the B complex before the blood tests?
Angel_of_the_North : No, but I didn't do that for either test. I did take some extra b12 in the intervening time, though. Does increased b12 lower or raise TSH test results (I thought it lowered them, but maybe I've got it backwards)?
Then if you were taking vitamin B complex, both tests are suspect
It’s essential to stop all supplements that contain biotin a week before ALL BLOOD TESTS as biotin can falsely affect test results
endo.confex.com/endo/2016en...
endocrinenews.endocrine.org...
Medichecks have I believe stated somewhere that biotin would possibly affect their testing
You are likely under medicated, unless very petite, guidelines on dose levothyroxine by weight
Even if we don’t start on full replacement dose, most people need to increase levothyroxine dose slowly upwards in 25mcg steps (retesting 6-8 weeks after each increase) until on full replacement dose
NICE guidelines on full replacement dose
nice.org.uk/guidance/ng145/...
1.3.6
Consider starting levothyroxine at a dosage of 1.6 micrograms per kilogram of body weight per day (rounded to the nearest 25 micrograms) for adults under 65 with primary hypothyroidism and no history of cardiovascular disease.
Also here
cks.nice.org.uk/topics/hypo...
gp-update.co.uk/Latest-Upda...
Traditionally we have tended to start patients on a low dose of levothyroxine and titrate it up over a period of months. RCT evidence suggests that for the majority of patients this is not necessary and may waste resources.
For patients aged >60y or with ischaemic heart disease, start levothyroxine at 25–50μg daily and titrate up every 3 to 6 weeks as tolerated.
For ALL other patients start at full replacement dose. For most this will equate to 1.6 μg/kg/day (approximately 100μg for a 60kg woman and 125μg for a 75kg man).
If you are starting treatment for subclinical hypothyroidism, this article advises starting at a dose close to the full treatment dose on the basis that it is difficult to assess symptom response unless a therapeutic dose has been trialled.
A small Dutch double-blind cross-over study (ArchIntMed 2010;170:1996) demonstrated that night time rather than morning dosing improved TSH suppression and free T4 measurements, but made no difference to subjective wellbeing. It is reasonable to take levothyroxine at night rather than in the morning, especially for individuals who do not eat late at night.
BMJ also clear on dose required
bestpractice.bmj.com/topics...
It's 30mcg of biotin in a daily pill (quite a bit less than the amounts in those 2 examples). And I didn't alter that amount of biotin between the two tests, just b12.
It’s that biotin is used as a reagent within the tests. Not every type of test, but a significant number
Medichecks have stated biotin can affect test results
Improving low vitamin levels can increase TSH
Low vitamin levels tend to lower TSH
Low vitamin levels leads to Poor conversion of Ft4 to Ft3
Improving low vitamin levels improves conversion , Ft4 often drops and Ft3 improves. TSH goes up and then can get dose increase in levothyroxine
Currently Ft4 is too low
Ft3 dire
Dr Toft, past president of the British Thyroid Association and leading endocrinologist, states in Pulse Magazine,
"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)."
(That’s Ft3 at 58% minimum through range)
You can obtain a copy of the articles from Thyroid UK email print it and highlight question 6 to show your doctor please email Dionne at
tukadmin@thyroiduk.org
So it sounds like I need to 1) retest with Medichecks after being off biotin for a few days (and off b13, too?) and 2) if my TSH and T3 are still not looking good, ask my GP for an increase in my levo dose. Does that sound right?
SlowDragon I just saw this post that indicates my NHS GP likely won't do anything based on a Medichecks test: healthunlocked.com/thyroidu...
Depends on the GP
My GP is more than happy to accept private test results
I haven’t had NHS test in 8 years
Private tests are often processes at exactly same lab as nhs tests
If just testing TSH, Ft4 and Ft3, then Monitor my health is currently cheapest option and is an NHS test.
Yes, good plan
How long have you been on 75mcg levothyroxine
Do you always get same brand of levothyroxine
Which brand?
Teva brand upsets many people
Alternatively, ask GP to retest thyroid including Ft4 and Ft3. Explain that at last test you were taking biotin, and hadn’t realised it would likely affect test results
(GP likely unaware of biotin issue)
I've been on 75mcg since June. Have been on same brand for quite a while -- Mercury.
Guidelines on dose by weight can be helpful in persuading GP to increase dose levothyroxine
I'm about 56kg, so kind of between doses on that front.
Currently taking 75mcg = 525mcg per week
So guidelines suggest 89.6mcg per day by weight = 627mcg per week
75mcg x 3 per week and 100mcg 4 per week would give 625mcg per week
You may need slightly more
Oh, that's an idea. If my GP balks at a full dose 25mcg dose increase, I'll suggest that. Will wait for word from Medichecks first on my question to them about accuracy and retesting.
SlowDragon , I got a retest from Medichecks after stopping my B complex supplement for a week. Latest results:
TSH = 2.76 (range: 0.27-4.2),
FT3 = 3.43 (range: 3.1-6.8),
FT4 = 16.4 (range: 12-22).
My GP is okay with (although not enthusiastic about) me increasing another 25mcg (which you'd recommended).
I just have one question before making the change: As per the top of this thread, my TSH was at 0.98 about 6 weeks ago (although I was taking biotin at the time), and I was under enormous pressure and stress in the weeks following that. I'm wondering if there's a link between high stress and high TSH that could account for the big increase I had in a short amount of time. If so, I'm wondering if I should give myself a few weeks of decompression time and then test again before upping my dosage?
Would love to get your thoughts.
Sorry missed this reply
Ft4 is only 44% through range
Ft3 a very low 8.9% through range
Helpful calculator for working out percentage through range
I would push for dose increase in levothyroxine
Currently very poor conversion
You need folate and ferritin levels test
SlowDragon , what about the stress question, though? If those results you're responding to were temporarily higher than my 'norm' because of the extreme stress, doesn't it seem unwise to use those results as a guide?
FYI that my ferritin was low in the test from October (29 from range 15-250). My last folate test was in May and was high (21.3 from range 2-17). I'm eating a lot of black pudding, iron, and kidney beans to get my ferritin up.
B12 probably won't make any difference but B complex contains biotin and can affect TSH results - if it does or not depends on the assay used by the lab - perhaps the two labs use different types of assay
Median TSH graph
healthunlocked.com/thyroidu...
TSH daily variation
healthunlocked.com/thyroidu...
researchgate.net/publicatio...
“According to the current TSH reference interval, hypothyroidism was not diagnosed in about 50% of the cases in the afternoon.”
“Further analysis demonstrated inadequate compensation of hypothyroidism, which was defined in 45.5% of the morning samples and in 9% of the afternoon samples”
ncbi.nlm.nih.gov/pubmed/252...
TSH levels showed a statistically significant decline postprandially in comparison to fasting values. This may have clinical implications in the diagnosis and management of hypothyroidism, especially SCH.
I think I’d better fast for a week then😂
Time of day can make a difference to TSH level, blood taken first thing in morning could be a bit higher than 2pm , have you taken this into account ? (however i would not expect so much of a difference as you have , especially in someone taking thyroid hormone replacement )
The other factor is that 3 weeks is long enough for TSH to have actually changed a lot.
Blood tests are a freeze frame of a moment in time, unless you took samples at the same blood draw and sent them to two different labs, there are very many things which would explain the difference that have nothing to do with the accuracy of the test.
Blood tests are just a clue to a puzzle , but are much more use when looked at as part of the whole picture.
They can also be affected by interference ,which might affect a test done on one platform , but not another. ie. academic.oup.com/edrv/artic...
Gophe I’d contact Medichecks with a copy of your NHS result and ask for a retest.
Was the exact same method used, i.e.
The earliest appointment - fasting (you can drink water) and don't take thyroid hormones until after the test?
If we had five blood tests on one day each test would be different.
New Medichecks Blood Test
Medicheck blood test results
Ferritin blood results different between medichecks and NHS
Annual NHS Blood Test
Medichecks blood test results
