There is a lot of talk about optimal thyroid levels. And rightly so. There are millions of hypothyroid men and women walking around underdosed. It is more the rule than the exception. We are being treated by doctors who don’t understand anything about thyroid issues. Even the endocrinologists don’t know anything. There is a TSH tyranny, and they don’t even operate with normal TSH values. NO ONE is ok with a TSH of e.g. 3. That is not a normal TSH. A healthy person typically has a TSH around 1 to 1,5. Here you can have a look at the levels in a large group of people (3875) in a study by Gullo et al from 2011, https://www.ncbi.nlm.nih.gov/pubmed/21829633 . These were patients coming to the clinic for nodules. So they were not absolutely healthy. But thyroid nodules are very common, and one can be euthyroid with nodules. (Nodules are often caused by iodine deficiency. If you have nodules, check your iodine status in urine, not serum) They had no clinical symptoms or biochemical (bloodwork) signs of hypothyroidism. They were considered healthy (euthyroid).
Table 1. TSH, FT4, FT3 levels in studied subjects by age and gender.
Reference range: TSH 0.4-4.0, FT4 9.0-20.6 pmol/L, FT3 2.9-6.0 pmol/L
Euthyroid controls 3875 age 49 (37–61)
TSH 1.40 (0.90– 2.10) FT4 13.8 (12.0–15.4) FT3 4.47 (3.85–4.94) FT3/FT4 0.32 (0.27–0.37)
Females all 3224 age 49 (37–61)
TSH 1.40 (0.90– 2.10) FT4 13.6 (11.8–15.4) FT3 4.40 (3.85–4.93) FT3/FT4 0.32 (0.27–0.37)
Under 60 yr 2457 45 (36–53)
TSH 1.41 (0.90– 2.17) FT4 13.4 (11.6–15.4) FT3 4.44 (3.85–4.93) FT4/FT3 0.32 (0.27–0.37) .
Males all 651 51 (35–64)
SH 1.29 (0.80– 1.94) FT4 14.2 (12.5–15.9) FT3 4.62 (4.16–5.30) FT4/FT3 0.33 (0.28–0.39)
Under 60 yr 470 45 (37–52)
TSH 1.30 (0.85– 2.00)* FT4 14.2 (12.5–16.0) FT3 4.79 (4.24–5.40)*FT4/FT3 0.33 (0.28–0.39) .
Over 60 yr 181 68 (64–73)
TSH 1.20 (0.75– 1.80)*. FT4 14.2 (12.4–15.6) FT3 4.47 (4.00–5.08)*FT4/FT3 0.31 (0.26–0.36)1
As you can see, there are variations between people. Of course, one cannot give absolute, exact numbers , there is too much variation for that. But it is not a TSH of 3 with FT4 and or FT3 very low in range, not to talk of under range. I see plenty of people with numbers like that being told by doctors, you are fine. Grown ups have a TSH plus minus 1.5, a FT4 a little under mid range and a FT3 around midrange.
It also seems, that young people might have a little higher numbers. The participants in Gullo’s study were grown people. In this study from 2008, Russell et al, they tested 29 students. You can see their numbers here:
|TSH||1.78 (1.64–1.93)||0.439 (0.174–0.703)||0240 (0222–0258)|
|FT4||16.2 (13.5–18.8)||0.097 (−5.81–6.01)||1620 (1521–1719)|
|FT3||5.42 (5.34–5.51)||0.187 (0.002–0.372)||0404 (0340–0428)|
As you can see, young people have a higher TSH, mean 1.8, FT4 a little over midrange and FT3 around 5.5 pmol/L.
Thyroid levels and race
Are thyroid levels the same for all races and ethnic groups? No, they are not. Which is important to know, especially for black people. Because black people have lower TSH than whites. You can see that here in a large, demographic US study of 16 533 people. They have included 3 groups, whites, blacks and Hispanics. People with goiter, thyroid disease or taking thyroid meds are excluded (disease free population). There are differences between the groups. Serum TSH, T4 and thyroid antibodies in the US population
For the disease-free population, mean serum TSH was 1.50 (95% confidence interval, 1.46-1.54) mIU/liter, was higher in females than males, and higher in white non-Hispanics (whites) [1.57 (1.52-1.62) mIU/liter] than black non-Hispanics (blacks) [1.18 (1.14-1.21) mIU/liter] (P < 0.001) or Mexican Americans [1.43 (1.40-1.46) mIU/liter]
So where whites had a mean TSH of 1.5 mlU/L, blacks’ was only 1.18. If you are black, it’s important to know this. Where a white person might start looking towards thyroid disease at a TSH over 2, you might suspect hypothyroidism over 1.8 maybe. If you have symptoms of course, and your FT4 and/or FT3 are out of whack.
They tested only the total T4. The mean T4 level was 112.3 +/-o.7 nmol/L. Reference range for T4 is usually 70-140 nmol/L. Blacks and whites had pretty similar T4, whereas the Hispanics had a little higher T4.
In this study, they found that healthy people have a total T3 of 146+/-24 ng/100 ml. That is 2.24 +/-0.3 nmol/L.
I include this info, as I believe there is so much confusion about what are normal levels. And there actually aren’t many good studies on it. Where it is checked for, that there are not hypo people mixed in. In the Gullo study, they also looked at vit D and vit B12 levels. That low levels here did not interfere.
A site like STTM claims, that normal levels are a FT4 midrange and FT3 high in range. This is not correct. And they don’t back this claim up either. It’s just an opinion.
As you can see, grown, healthy people have a FT4 a little under mid range, with a FT3 around or a little over mid range. Women have higher TSH and a little lower FT3 than men of the same age. This surprised me, as I have seen other studies showing a higher TSH in men. But how you feel, is always what’s important. You could be someone who used to be high normal. Now you are low normal, and you feel it.
You see the numbers FT3/FT4. That is the conversion ratio. It shows how well you are converting. These graphs are from the Gullo study, same as the table over. The line is for people taking T4 medicine, and the shaded areas the normal, healthy people. The people on T4 had a mean conversion rate of only 0,21, and the healthy people of 0,31. So no wonder we hypo thyroid often need some T3. You can estimate that yourself. If it is under 0,23, you don’t convert well enough. If the ratio is between 0,24 and 0,26 you are a moderate converter. Over 0,26 is a good converter. If you are under 0,24, you are probably in need of some T3 containing medicine. Or you can try to increase your conversion with supplements and herbs. If FT4 is 19 and FT3 5,0, then the ratio is 0,26. You might also have too little T4 in your body, and an increase in T4 medicine might increase your FT3 adequately. With a conversion ratio of 0,26, you might still need some T3. It is very individual how high Free T3 people need. How you are feeling is always what’s important.
I have seen many on Facebook and internet sites, believing that healthy people have a FT4 mid range with a FT3 high in range. Maybe they have this misunderstanding from STTM. I have seen admins in groups claiming this, ecsp in US groups. It reveals a lack of understanding of how the thyroid system works. A healthy person does not NEED very high levels, as he or she can produce more hormone when needed. If you just think logically, why would someone who can convert T4 to T3 in every cell, have a lot of FT3 floating around in the blood? When all of us who take T3 containing medicine, and who need high FT3 levels because we DON’T convert in our cells, we know that a high FT3 can be uncomfortable. We can feel nervous, get palpitations. And we know that high FT3 does deplete calcium from our bones, at least with hyperthyroid. It would make no sense for a healthy body to have a high FT3.
This misconception makes for bad advice. I have seen people with perfectly normal levels being told in thyroid groups, they are too low and in need of medicine. Of course, if someone has Hashimotos, have anti-TPO antibodies, that is a different matter.
When we are hypothyroid, we need to have a higher FT4. We can’t produce more T4. We need to have enough to meet any situation or stress during the day. Those who do good on T4 medicine, convert well. But very few convert as well as a healthy person. I have only seen that a few times. Most hypothyroid will have a conversion ratio under 0,30. So we need to have a higher FT4 in order to get FT3 midrange or a little over. But if your conversion ratio is under 0,24, you will not do well on T4 meds. Even with a higher conversion ratio than that, you might need some T3 medicine. Many people may do better with less T4 medicine in their body and some T3 instead. If one doesn’t convert well, one doesn’t do well on T4 medicine. But if you convert ok, there is no need to have FT3 high in range. Then you are more like someone without thyroid issues, you can convert more as needed. Around or a little over midrange should be enough. I see that internet sites and again admins in Face book groups, claim, people on T4 should have a FT4 in midrange and a FT3 high in range. I very seldom see numbers like that. I have seen under 5 persons with that kind of numbers in all my time. Maybe people doing well on T4, and for that reason they don’t seek out our support groups. Maybe they more often have numbers like that. I don’t know. I believe this is a misunderstanding. I have gotten a lot of flack in US groups for saying this, I have received long, angry pm’s from admins. There are a lot of militant people in these groups. I sometimes think, these people are as stubborn as the endocrinologists.
The renowned scientist, Hoermann even says in this study from 2019, some people might need FT4 OVER range, in order to produce enough FT3, https://europepmc.org/article/pmc/pmc6726361. I think most people will prefer some T3 medicine instead, though. Rather than such high levels of FT4. I would think there would also be a danger of high reverse T3 .
In saying this, please remember, how you feel is always what matters. If you still have symptoms with a FT3 around midrange, then you need other meds. Some synthetic T3 or NDT. Or maybe another T4 medicine. Lots of people have a lot of side effects on the various T4 meds. I personally cannot tolerate Levo at all. I get a rheumatoid aching in my upper back, shoulders and neck. I also feel tired. I read, many feel the same way. There is now Tirosint, which only has 2 fillers: the gelatine capsule and glyserine. Here is a new study on the inconsistency of Levo, study. I am hoping for more studies on Levothyroxine and side effects. Very important.
What about TSH?
Where should the TSH lie? Many patients think, we should not look at TSH at all. I see this a lot in US groups, not so much here in Scandinavia. That is another misunderstanding, in my opinion. I get the negative feelings about TSH, as we are positively abused with it. In many countries we don’t even get anything BUT TSH measured. No wonder many almost fear the TSH. But to say, we should not take TSH into consideration at all, is a misunderstanding. And reveals a lack of understanding. Dr. David Brownstein thinks the same way. He says, we should neither over-or underestimate the TSH. TSH can never stand alone, it must always be considered together with the free hormones. When it comes to diagnocing central hypothyroidism (issue in pituary/hypothalamus), it is absolutely necessary. It is useful also in primary thyroidism. In particular when it comes to upper range. For most people on T4 meds, it should not be over 1, can be a little higher for the elderly. It is harder to set a lower range. Some say 0,5, others 0,3. But some can have even lower, and do well on that. And one can have issues in the pitiuary/hypothalamus that pushes TSH down, and that neither patient or doctor understand. It is more common than one maybe realizes, I see it a lot in the groups. And remember, TSH falls sharply after 9-9 30AM. That is why it is so important to do labs before 9AM.
When your conversion ratio is less than 0,24 you convert poorly. You cannot convert as needed, that is, you need to have a FT3 level that is high enough to meet any situation. That is why one needs to have a higher FT3 than those who convert. This is what doctors don’t seem to understand. To me it is very simple, but apparently not. Most people on either synthetic T4/T3 or NDT, need to have at least FT3 on 5,5 pmol/L (when range goes to 6,8)(5,5 pmol/L is 3,5 pg/ml or 3,5 ng/L) . I like it over or around 6 (3,9 pg/ml). Many need it at top of range, some even over. It’s best with a FT4 in mid range, but on NDT, it can become lower. The various NDT contain different amounts of T4, 60 mg Erfa contains 35 mcg T4, whereas Armour and Nature Throid contains 38. Thyroid S also contains 38 mcg. FT4 will naturally vary accordingly. For some, FT4 also lowers on NDT as the years go by. With synthetic medicine, it is easier to regulate the FT4 level. I see so much under dosing with T3 medicine here in Denmark, people get only 5 to 7,5 mcg T3. They adhere to this idea of 17:1, 17 parts T4 to 1 part T3. That is, if you get 100 mcg T4, you will only get 5 mcg T3. A healthy thyroid produces app 90 mcg FT4 in a day and app 5 mcg FT3. But there are big individual differences. Very big, you can see how big here:
As you can see, there are huge differences between individuals. From 6,5% to 42% excretion of T3 from the thyroid! The rest of our daily app 30 mcg T3 is converted in the body. App 70% in the liver, 20% in the kidneys, some in the intestine apparently. I have read as much as 20%, but I haven’t seen any actual studies on it. It’s the good bacteria that convert. But the larger part takes place in the liver. So a lot hinges on the liver, how healthy it is. I believe very many grown women have a sluggish liver.
Danish doctors don’t understand, that we don’t only miss the 5 mcg the thyroid produces, we don’t convert. This is the paradigm, leading to very under dosed patients. And doctors and scientists concluding, T3 does not improve symptoms and quality of life. As many scientists study the effects of T3 with under dosed patients. That is what is called invalid studies, one doesn’t study what one claims to study. T3 given in doses that let patients become optimal improves symptoms immensely!
Suppressed TSH is doctors worst nightmare apparently. Most doctors don’t really know anything about it, they haven’t read the research. It’s something they have been told in school, that low TSH puts one at risk for osteoporosis and heart issues. There is a lot of science refuting this today. I don’t know why doctors don’t keep updatet. Thyroid disease is after all a very common, widespread disease. I will look at studies on this on the blog. I am not claiming, that suppressed TSH cannot cause issues. I think the jury is out on that. There are contradicting findings. I have gotten osteoporosis myself. If it is caused by my suppressed TSH, how much I have lived with a low FT3 or that my calcium, vitamin K and boron levels have been too low, I will never know. I do know that it would never have gotten so far before being diagnosed if I had stayed in Norway. In Norway, the doctors look to prevent disease. Testing for vitamins ans minerals is an everyday thing. In Denmark, they refuse to test. If politicians knew how many billions the Danish doctors and their incompetence cost society!
Boron is very important, by the way. Funnily enough, I have never heard doctors worrying about the dangers of too low FT3. And THAT is dangerous. Not to talk of the pain it entails for the person in question, dragging along, unable to enjoy life.
I think the argument about whether suppressed TSH is detrimental or not, is somewhat of a blind ally. For me the argument must be, that I, as a grown up, must be allowed to make an informed decision. I don’t think we as patients should blatantly deny, there can be risks. We cannot say that. We can say, the risks of too low FT3 are obvious and well documented. We simply WILL NOT live like that.
Concerning osteoporosis, we can do what we can to prevent it. THAT is what doctors should help us with, making sure our calcium levels, magnesium, vit D, vit K2, boron, silica, all those are optimal. And let us have a life worth living. I wish we could have all doctors living with a FT3 barely within range for a few weeks or months. I am telling you, things would change! What other group of patients are being given so little say over their own treatment? And we are talking cheap treatment. But we become costly as we don’t receive adequate treatment, high cholesterol, heart disease, diabetes, fibromyalgia all ending in a disability pension. If politicians realized how much money could be saved on giving us the right treatment from the start, how much doctors’ incompetence in this field is costing!
I don’t mean research on the effects of suppressed TSH is not important. Of course it’s important. But I think we can stay stuck in this back and forth. And doctors don’t read the science! We cannot discuss on a professional level, as they are not informed. There are many exceptions, but the good doctors are few and far between. And most doctors do not take well to patients bringing them studies to read. So talking more in terms of symptoms, how bad one feels, the fact that one’s FT3 is too low, why not try and see. And just that we want to have a good life while living.
It’s absurd, how they seem to be so concerned with our health later in life,but not with our life here and now. Their waiting rooms are full of overweight people drinking and smoking too much. Worry about THEM!
But if you have a GP who will not let you have a low TSH, I would recommend, finding another. If you find he or she despite this, is open to you, you can try showing him or her this study, https://www.ncbi.nlm.nih.gov/pubmed/26940864 It’s a retrospective study looking at people who used Lio over a 17 year periode. They found no increased incidence of osteoporosis or heart issues. The other one is an article from Thyroid Patients Canada. It’s on Triac. I had never heard of it before Tania Sona Smith wrote about it. It is a thyroid metabolite, that increases when one takes T3. It’s actually something good. But it suppresses TSH, https://thyroidpatients.ca/2020/01/02/when-dosing-t3-you-get-higher-levels-of-triac/.
We patients know more about optimal levels than our doctors. The doctors think we are ok when we are under dosed. When we of course, still have hypo symptoms, they babble about menopause, depression, overweight. They prescribe statins, diabetes meds, beta-blockers, anti-depressants. WE ARE UNDER DOSED. We need to get the thyroid meds and to have the levels where we feel ok. And we can judge this ourselves. We are grown people, we know how we feel!
Some people do best on T3 only. Maybe they convert FT4 to Reverse T3, and not FT3. It’s difficult to get the doctors on board with this. But when everything else has been tried, and you still don’t feel good, you might be allowed to try. I see that more and more people try T3 mono. But I also see, people going back to T4/T3 combo or NDT. I don’t think T3 mono is good for most people. It’s unstable, one has no storage hormone.
I don’t have any personal experience with T3 mono. I could never do it, I feel very jittery on synthetic T3 meds. I must have NDT. People say, the lactose free Thybon is more mellow than Liothyronine.
In thyroid health, one estimates that people use app. 30 mcg /day. We don’t absorb thyroid medicine 100%, maybe 70%. So most people will need at least 40 mcg T3/day. Many will need more, up to 80 mcg is not unusal.
There is a study on T3 mono from 2016. The study is pretty useless, as most of the participants are underdosed. They are given from 30 to 45 mcg T3. The point of the study is to look at once a day dosing regime on T3 mono. But they also draw conclusions on symptom reduction. Which you can’t when people are underdosed. Their FT3 lies around 4.1 pmol/L/2.7 pg/ml. I am dead at that level. And people on T3 mono often need a higher FT3 than us on NDT. So totally useless. It says something about parametres like TSH though, and shows clearly, that the FT3 peak comes 2 hours after ingesting. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4913511/
I just mention this study, so that you understand, under 40 mcg will be too little for just about everyone.
When dosing with T3 mono, all that matters is the FT3 number. The FT4 will be very low of course, and TSH will be high. I don’t think one can use the TSH for anything in T3 mono teraphy. TSH listens to the FT4 mostly, and that is why it becomes low in T3 mono. I have seen people with low TSH in T3 mono, but it will often be high.
How to do labs when on T3 mono? You can’t do it first thing in the morning, medicine fasting. Your FT3 will be at it’s lowest at that time. I would take my morning dose, and do labs 3 to 4 hours later. There must be at least 3 hours in my opinion, as the FT3 peaks 2 hours after dosing, and your FT3 will seem very high if tested at that time.
If you want to read more about T3 mono, written by someone on T3 mono, have a look at Paul Robinson’s blog https://paulrobinsonthyroid.com/.
Tania Sona Smith on Thyroid Patients Canada is also on T3 mono, and writes about it,
There are several Facebook groups for people on T3 mono.
It’s important to consider, that laboratories are very inconsistent in their testing. I have become acutely aware of this after testing on an internet lab one week, Letsgetchecked, and a hospital lab the next week. At Letsgetchecked I had a FT3 of 6,7 pmol/L and at the hospital, 5,5 pmol/L. Shocking! And in many countries they now also narrow the ranges, I guess to keep people under dosed.
The main thing must therefore be symptoms, Take your pulse and temperature. Those are the best indicators. People may vary a bit in their temp, but a morning temperature under 36 Celsius or 96,8 Fahrenheit is for sure too low. Mine must be at 36,5 C at least. In the evening I need to be at 37 C at the lowest. I can go up to 37, 2 and still feel good.
I have seen thyroid bloggers write, temperatures have come down over the last 100 years. I have read studies saying the same. For one thing, only the old fashioned mercury thermometer is accurate. And that should be applied INSIDE the body, and stay for 8 minutes. Temperature apps are no good, you realize that when they give different results with minutes in between testing. In the studies being done, some rely on app testing. There is no screening for disease. I believe as there are so many undiagnosed and untreated hypothyroid in the world, they skew the results. There has been a large increase in hypothyroidism. I just don’t buy, that the body has changed that much in a 100 years. Why, we are very much the same since thousands of years ago. I believe a low temperature is a sign of disease. I might be wrong. Try it out for yourself, see at what temperature you feel good and warm.