I have had sub-clinical hypothyroidism (diagnosed by TSH level only 😕) for approx 20 years.
I was made aware of this and prescribed Levothyroxine only a couple of years ago when my TSH reached 10 (apparently full-blown hypothyroidism).
The thing is, my FT 4 has always been at high end of the normal range. It has fluctuated between 10.7 and 14.2 in the last twenty years. Normal range (7.9 - 14).
FT3 rarely tested but last time it was tested (after being off meds for a few months), it was 6.2 (normal range 3.1 - 6.8) so above optimum
TPO (measured at same time normal (<0.3). Normal range 0.0 - 9.0
I was prescribed 50mg Levo in Dec 1921.
In July 2022 I had symptoms of being hyper - sweating, jittery, palpitations.
I stopped taking Levo for a few months and hyper symptoms subsided.
GP referred me to endo and measured prolactin - normal.
Endo reduced Levo to 25 mg. This reduced my TSH from 9.135 (Jan 2023, before resuming Levo on reduced dose) to 3.897 in May 2023. FT3 and FT4 not measured at this time but there have been times when FT4 has reduced while taking Levo. Levo appears to reduce my TSH but to be ineffective with regard to FT4 which is always at optimum level, regardless of Levo.
I have 2 questions:
Do I really need Levo?
Why does Levo reduce TSH but not increase FT4.
Endo says FT4 will eventually decrease if I am not on Levo but I spent 20 years with high TSH and FT3 and FT4 at optimal levels, and with TPO normal.
Am I a medical mystery? 😄 I have Googled and Googled and found nothing to help.
I have GP appointment on Tuesday and would love to get this sorted once and for all.
Sorry for long lost. Thanks in anticipation, all.
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Plus have you ever had TPO and TG antibodies tested
Have you had cholesterol levels tested
ALWAYS test thyroid levels early morning, ideally just before 9am, only drink water between waking and test and last dose levothyroxine 24 hours before test
Suggest you test via Medichecks or Blue horizon
List of private testing options and money off codes
I was prescribed 50mg Levo in Dec 1921. - You must mean 2021?
High TSH with high in range FT4 & FT3 is very unusual.
Are tests always sent to same lab? Might be some sort of test interference.
Antibodies can affect TSH, as your TPOab is not positive you should test TG also.
Do you take any supplements? Biotin can skew test results.
If your FT4 & FT3 are in range adding replacement will takes you over range & causes hyper symptoms. Then your doctors are raising your levels to get the TSH to lower in range.
Ask for a referral to endocrinologist to check your pituitary hormones. Benign adenomas can secrete TSH, very rare but should be ruled out.
If FT4 & FT3 were naturally over range I would suggest testing TSI & TRab antibodys (Hyper Graves antibodies). As FT4 & FT3 are within range & TSH high doctors will be unlikely agree.
Genetics can sometimes cause naturally high TSH & FT4, FT3 ie it might be normal for you but abnormal for 99.9% of the population.
Have you had folate, ferritin, B12 & Vitamin D tested recently?
All vits and minerals tested recently after (unrelated) cancer scare, which thankfully turned out well. All normal and I don’t take biotin.
Yes, Levo first prescribed in December 2021.
The same local hospital has carried out the tests for the last 18 years. I have had 17 tests during that time and the pattern has always been:
TSH raised when not on Levo, reduced when I am.
FT4 slightly fluctuates but always top end of normal range, regardless of Levo. It sometimes slightly reduces on Levo, although TSH always reduces.
FT3, rarely measured, but was at very high end of normal range when it was last measured, after stopping Levo for several months.
Yes, the focus seems to be totally on getting TSH down. If my FT4 is normal why am I prescribed it?, I ask them. Answer is always that FT4 lags behind TSH and will eventually decrease. But it has been 20 years!
GP had prolactin measured as she wanted to rule out pituitary tumour but that was normal. She put me under eno who wants to keep me on mild dose as TSH had reduced, but so had my FT4 (although still high end of normal range).
I am so confused and really don’t want to take meds I don’t need,
If I had a pituitary tumour, would meds still decrease TSH, as it does?
FT3 and FT 4 are well within normal range, so Graves not suspected, especially as TSH is high without Levo.
I can’t find anything to explain the situation, anywhere, and am happy to take the meds if needed, but I worry that they aren’t.
“FT4 slightly fluctuates but always top end of normal range, regardless of Levo”
This is because your system is trying to maintain the right FT4 & FT3 for your needs. The TSH adjusts to signal thyroid to produce the right level.
“FT4 lags behind TSH and will eventually decrease. But it has been 20 years!”
Really? TSH is the hormone which reflects & respond to FT4 & FT3 levels. TSH follow FT4 (& FT3) Not the way around. I think they make stuff up as they go. If your doctor understood how the HPT axis worked they would know this. They have their understanding of the feedback mechanism wrong. They are giving you L-T4 in the hope it rises FT4 & lowers TSH. You already have higher levels of FT4 but they are still raising it expecting the TSH lowers but replacement ultimately it will replaces what the thyroid produces. This is why increases are required to lower TSH further.
“prolactin measured as she wanted to rule out pituitary tumour but that was normal.”
Prolactin isn’t the only pituitary hormone, there are many others.
TSH is from the anterior location of pituitary. Other hormones secreted from anterior are:
* Adrenocorticotropic hormone (ACTH, or corticotropin): This hormone stimulates your adrenal glands (the glands on top of your kidneys) to produce cortisol and other hormones.
* Follicle-stimulating hormone (FSH): This hormone stimulates the testes to produce sperm and stimulates the ovaries to produce eggs and estrogen.
* Luteinizing hormone (LH): This hormone stimulates ovulation in women and testosterone production in men.
* Growth hormone (GH): In children, growth hormone stimulates growth. In adults, growth hormone helps maintain healthy muscles and bones and impacts fat distribution.
Yes, my TSH appears to rise without Levo for no apparent reason, and, in my eyes, I am taking Levo merely to reduce TSH - when my FT4 is absolutely fine.
I think - because Prolactin was normal - adenoma was ruled out. I may request other pituitary tests, but am afraid of coming across as a hypochondriac. Do you think I have reason to think the problem may be in my pituitary gland?
There seems to be an obsession with just diagnosis being solely based on TSH.
It might explain the high TSH accompanied by in range / higher FT4.
Unfortunately doctors do not seem to have any curiosity to investigate why your TSH is high without the expected low FT4 and are just prepared to treat as if they were low. ie giving L-T4 when you have in range FT4 levels.
The obsession is not only with diagnosing by TSH, but treating / monitoring too & TSH is not a reliable measure.
If you did have a pituitary adenoma (and that is only a possibility). You might have a micro group of cell secreting a bit “too much TSH”. It’s still possible the pituitary still functions & will still respond in the expected way, ie your pituitary TSH level will still increase & reduce in accordance to your FT4. It just that the adenomas bit will continue to over secrete TSH in comparison to your thyroid levels.
That is how I would view it, others could have a better understanding / better way to explain or different theory than me. When it comes to thyroid it can get confusing because not all the information is collected in 1 go & even it was is doesn’t all make complete sense without a comparison / history.
Have all your tests been as recommended?
I remind myself of things to remember for blood tests with this checklist
A - Always check what’s being tested & collect test results with reference range.
B - Biotin - cease 3-5 days before draw to avoid possible test interference
C - Consistent unchanged dose - minimum 6 weeks previously.
D - Delay replacement dose on day of test (until after blood draw)
E - Early morning appointment. (Book draw as close to 09.00 as possible)
F - Fast overnight. This can have a slight impact. Drink lots of water
Testing at different times / different circumstances can cause fluctuations to results.
I have the opposite situation as I have a thyroid adenoma (called toxic nodule) it autonomously (over) function. The TSH drops as expected with elevated FT4 & FT3. I can take medication to lower what FT4 & FT3 can be produced. Lowering it should raise the TSH. but my TSH now doesn’t respond to low levels because the TSH was undetectable for a prolonged time, my levels were missed for years. It’s “stuck” being low, but while down regulation is well known, (low TSH, low FT4 & low FT3) the reverse (high TSH, FT4 & FT3) isn’t discussed.
raised TSH is (usually) the most obvious early warning of a thyroid problem before T4 production eventually falls through floor (when thyroid has failed completely)
in most cases of primary hypothyroidism the TSH goes over range ( 'sub-clinical' ) many months / years before the T4 finally goes under range ('overt').
Yes, I took it to mean that - but would have expected FT4 to have started to decrease. It was eighteen years before diagnosis. TSH was at warming degrees of high during that time, and FT4 always at the higher end of normal range.
Do you know whether Levo would decrease TSH if I had a pituitary adenoma, as it does decrease it, but doesn’t raise FT4, and doesn’t need to.
Wrote an answer , changed it, thought about it , edited it again, then realised i'd confused myself ... it's tricky to get the head round what 'should' be happening in that situation.
might try again later if thoughts become any clearer .
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maybe you are one of those people who don't feel any symptoms of hypo until TSH is stupidly high ... like 50 /60/70/ 80 +... they do exist .
as you say ... maybe the symptoms you felt were reproductive hormone related , not thyroid .
the high/ rising TSH has been picked up incidentally while GP looking for cause of symptoms .
So (theory) you are going slowly hypo.... thyroid is needing more stimulation to make same amount of T4 as before , but you wouldn't have ever noticed until fT4 levels were MUCH lower ... which could take decades/ never.
if it was a pituitary problem , i don't think a relatively small increase in T4 intake from 25 / 50mcg Levo would lower the TSH by very much.,,, perhaps by a small amount , which might explain why your T4 level falls on levo (less TSH leads to less stimulation of thyroid to make as much T4 ) ,,, but essentially a pituitary problem causing 'too much' TSH production is not much affected by adequate / high/ low T4/T3 levels ... whatever was making the pituitary produce 'too much' TSH would still be doing it regardless of low/ high T4/ T3 levels.
Yes, I understood that endo thought I was going slowly hypo. FT4 appears to be totally unrelated to Levo - fluctuates slightly, but always at top end of range, regardless of Levo . It sometimes reduces a little on Levo, sometimes increases a little. I wonder if I really need Levo if this is the case, given that FT4 has remained the high end of normal since I first had tests twenty years ago.
The Levo is certainly decreasing TSH though. It went down from 10 to 1.26 when I was on 50 mg.
Do you you think that suggests a pituitary problem? Sorry- I was unsure by your last paragraph. I have been trying to research too and my brain has become a bit befuddled with it all 🙃😀
To clarify , no i don't think it suggests pituitary issue,, because a pituitary issue would still be causing 'too much' TSH production even when you took levo..... .it would not be falling to around 1 ~ TSH of around 1 is a normal/ settled level for most people when there is an adequate T4 production/ supplementation.
personally i think it's possible you don't actually need to take levo at the moment but endo is playing safe to get TSH down ~ because there is legitimate evidence of increased risks for all sorts of things when TSH is over range (and increasingly so once it gets towards 10 or over ( eg increased risk of heart issues/ raised cholesterol/ bone issues etc etc ) However you need to bear in mind this is a statistical risk and those risks are probably related to the fact that most people with high TSH will have much lower T4/T3 levels than you , rather than their TSH 'itself' causing any increased risks ..... you don't fit that box at the moment because you still have plenty of T4/.T3 ... so arguably those increased risks may not actually apply to you ?
But if taking levo doesn't cause you any problems ,then i cant see any good reason to worry about taking it ... it's just a synthetic copy of the T4 you make naturally .. as opposed to a drug/ medication in the usual sense , there's nothing inherently bad for you in it.
one thing it may affect ..... Higher TSH causes relatively more T3 production direct from the thyroid ( it acts like an emergency T3 'boost' and increases the ratio of T3:T4 that the thyroid makes ..most T3 is made in the body from conversion of T4 , but some T3 is provided 'ready made' from the thyroid)... so by lowering TSH you may be loosing this emergency T3 boost , and you may find you have relatively lower T3 levels when taking levo.... but if you feel well on levo i don't think is a problem .
Thank you so much Tattybogle. This is really helpful. I had been pondering over what you explain in your first paragraph for some time. What you so makes sense, but I just wasn’t sure whether the Levo could stop an adenoma producing too much TSH. I will request a T3 test tomorrow. I can’t understand why docs aren’t more keen on measuring this. 😕
Hi Finne. Yes, I had classic symptoms - debilitating fatigue, low mood, unexplained weight gain, but also palpitations, increased hunger and flushing/sweating. These have been alleviated by HRT, so I now suspect they were unrelated to thyroid. Thank you for your reply. I hope you are now well.
I had all the classic symptoms - but started HRT last year and the symptoms were alleviated. I had to come off HRT temporarily earlier this year, and symptoms came back with a vengeance, despite being on Levo. So I now think symptoms may never have been caused by hypothyroidism, but the situation is confounded somewhat, I guess I could come off Levo and see what happens, but then my TSH will keep creeping up.
We present a patient treated for hypothyroidism, it was later found that human anti‐mouse monoclonal antibody (HAMA) had interfered with the TSH assay.
We conclude that the presence of heterophilic antibodies should be considered when measured TSH concentrations are not compatible with either the clinical history or other thyroid functions tests.
My TSH does decrease with Levo, though, unlike the example here. It’s just that my FT4 doesn’t rise - and doesn’t need to, by all accounts. I am very confused. 😕
The thing is, my FT 4 has always been at high end of the normal range. It has fluctuated between 10.7 and 14.2 in the last twenty years. Normal range (7.9 - 14).
Has the range for Free T4 never changed for you in 20 years? That would be unusual for Free T4 I think. It might be worth checking.
To compare test results where the range has changed over the years, we suggest using one of the percentage calculators to work out the percentage through the range for each test, making sure to use the range given with each test result.
If you don't have the symptoms of hypothyroidism then you don't really have hypothyroidism and this is borne out by your t3 and t4 levels. Symptoms are the gold standard of diagnosis for hypothyroidism- not blood tests.The tsh is high. But this is a pituitary hormone and in your case appears to produce excess tsh. However, it looks like your thyroid is nonetheless doing what it should do. Which is interesting and unusual.
So no, you don't need levo if you don't have hypothyroidism. This is borne out by your reaction to levo.
Here's a thought. We say your bloods are unusual- because they are. But there is probably a huge sampling bias. People with high tsh, normal thyroid hormone levels and no or few symptoms are unlikely to have a thyroid blood test let alone post them on here. So whilst they are unusual they may not be quite as unusual as we think?
Hi Cornwaller. Thank you - I see what you mean. I had classic symptoms for a long time, which I was certain were caused by thyroid, but the issue is confounded a little as I was prescribed HRT also and now think my symptoms may have been menopausal. I guess I would have to stop each, separately, to find out. I did feel ok whilst on HRT and stopping Levo for a while last year, but I only stopped for a couple of months or so and had no blood tests during that time (I was abroad).
I think I’ll ask GP for FT3 test to shed some light. It’s rarely been done, and def not for some time. Thank you for your reply.
Over the years the medical profession has become increasingly reliant on blood tests to diagnose a condition.....to the exclusion of nearly all signs and symptoms. My point is do you actually have any signs and symptoms of Hypothyroidism? You maybe right & that back in the 1960s before blood tests you probably wouldn't have been diagnosed as Hypothyroid. Question is has the medical profession become slaves to the blood assays to the exclusion of using real clinical judgement?
Hiwaveylines. Thank you for your reply. Yes, I had classic thyroid symptoms, but since starting HRT I now feel that the symptoms may have been menopausal. It’s tricky, being confounded by both meds, I guess.
Thyroid, ovaries and adrenals are all affected by each other.... I was once told this by a well woman doctor. She reckoned by addressing a problem with one it brings the other two into balance. It maybe this has happened to you?
Had some bad experiences of my own. I will share what I wish I had known. Check selenium cause without adequate selenium you won't absorb iodine and you need iodine to have a correctly functioning thyroid. Iodine is a huge reason by there are so many thyroid issues! We have tons of "manipulated foods" that leave us iodine deficient . Check reverse T3. Please look into these thing you just might save yourself a ton of pain!
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