Thyroid patient’s on T3-only treatment, or mainly T3 with some T4, should not rely entirely on thyroid blood tests to try to check if their dosage of T3 is correct
I believe there is too much importance placed on using thyroid blood test results to manage the dosage management of T4/T3 combinations. As patients increase T3 and decrease T4, the usefulness of thyroid blood tests to determine if the treatment is correct declines further. The thyroid laboratory ranges for FT4 and FT3 also become inapplicable to T3 therapy. These lab ranges are developed for healthy people or people on T4-only medication. They do not work well for those on T3-Only or T3-Mostly medication. When doctors try to manage a patient’s T3 treatment to conform to thyroid lab ranges this often leads to the patient remaining with symptoms.
I have to say once again for completeness that thyroid blood tests have an important role in the diagnosis of hypothyroidism.
My typical thyroid blood test results back in 2012 looked like this when testing around 12 hours or less after my last T3 dose (on my 60 micrograms or so of T3 per day – which is quite a modest amount compared to some patients):
- TSH was often near zero (but by leaving a gap of 18 hours or more between the last T3 dose and the blood draw, TSH can sometimes become higher and a prescription reduction avoided).
- FT4 was 0.3 pmol/L (lab reference range 12.0–22 pmol/L).
- FT3 was 8.9 nmol/L (lab reference range 3.1–6.8 nmol/L) (but by leaving a gap of 18 hours or more my FT3 could get close to being in the reference range – often 18-24 hours or more might be needed for some patients).
My thyroid is dead now, having had Hashimoto’s for around 30 years, and I take no T4 medication, hence my FT4 is near zero. I use T3-Only, hence the high FT3.
Most patients on T3-Only have:
- High FT3 (close to or sometimes over the top of the reference range).
- Low FT4 (often below the bottom of the reference range due to low TSH).
- A suppressed or very low TSH.
See this link with 2016 research which shows the effects on TSH of a T3 dose:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5167556/
See this blog post also that explains why having a low TSH when on thyroid treatment does not automatically imply that the person is over-treated with thyroid medication:
https://paulrobinsonthyroid.com/is-it-safe-for-tsh-to-be-low-or-suppressed-on-thyroid-treatment-research/
Often patients on T3-Only are in a long-running battle with their doctor or endocrinologist to reduce their T3 dose because of low TSH, or high FT3, or to add some T4. Reductions of their T3 dosage or adding T4 frequently make their symptoms worse.
I have a once-a-year thyroid blood test, as my doctor has to do that to conform to admin rules. We do not necessarily act on these results. Some doctors might assume I was thyrotoxic given my FT3 level, but I am not remotely close to this.
Thyroid blood tests are only a rough guide as to whether our cells are getting and using the thyroid hormone they need. They are an accurate estimate of blood levels but can be desperately inaccurate in terms of cellular levels of thyroid hormones.
In particular, thyroid blood test results sometimes do not reflect how well or unwell the thyroid patient actually feels. Attempting to use thyroid labs alone is likely to result in the thyroid patient remaining hypothyroid, especially if FT3 is too low for the individual person.
Only the active cellular level of thyroid hormone counts, and we cannot measure this with any laboratory test yet. High blood levels of thyroid hormone cannot cause bone loss or heart problems or any other problems, as thyroid hormone in the blood does nothing until it reaches the cell nuclei and the thyroid receptors within the nuclei.
However, there are ways to assess the effect of the biologically active T3 thyroid hormone within our cells
Many years ago doctors would have used a complicated apparatus to measure Basal Metabolic Rate (BMR). In fact, this BMR measurement used to be the only diagnostic method for detecting hypothyroidism. The BMR measures the energy consumed by the body when completely at rest. If a patient had hypothyroidism then their basal metabolic rate would have been very low.
However, now we have to adopt a simpler, but still effective, approach to provide data on how well thyroid hormone is regulating cell function.
Symptoms and signs are indicators of cellular levels of thyroid hormone
So, we have not got a laboratory test that indicates how well thyroid hormone is actually regulating our cells. So, what can we do?
All we can do is measure the effect of these thyroid hormones on our bodies. This is what I have done for well over twenty years. I use symptoms and signs.
A doctor describes a sign as something that is objective and can be measured. A symptom is a subjective assessment of something.
So, a patient may say, “I feel cold”. Feeling cold is the symptom and body temperature is the sign.
Anyone who suspects that they are still hypothyroid can track symptoms and signs every day and build up a diary record of these, which can be used to determine if they are hypothyroid at the cellular level. A doctor who is not open-minded may not accept this of course.
However, for someone on T3-Only, this is currently the ONLY reliable method, to manage the T3 divided doses, until some researcher comes up with a proper test of thyroid hormone that shows how well thyroid hormone is actively regulating cell function.
Anyone on T3-Only who has a doctor who is attempting to manage their T3 dosage entirely with thyroid blood tests (TSH, FT4, FT3), needs to be aware that this is likely to fail. It is likely to result in very bad decisions being made that could easily keep the thyroid patient hypothyroid. If this is the case, the patient should consider changing their doctor. This may also be true of people who take predominantly T3 with some T4.
Note: when beginning to use T3 therapy checking thyroid labs from time to time does make sense. It is helpful to know that FT3, FT4, TSH and possibly reverse T3 are all adjusting as you would expect them to.
Here is the list of symptoms and signs that I use on a regular basis:
Symptoms:
- Mood.
- Anxiety (including restlessness, hyperactivity or irritability, being anxious, edgy, tense, and unable to relax, usually means too much thyroid hormone).
- Mental ability and clarity.
- Energy level.
- Muscle weakness.
- Digestive system performance.
- Condition of skin, hair, and nails.
- Heat or cold sensitivity.
- Muscle aches or pains.
Signs:
- Resting heart rate.
- Blood pressure.
- Body temperature.
- Weight gain/loss.
I have been brief with the list of symptoms and signs, and not explained fully how I use them, but the list should give a pretty good indication that dosage management with T3 is not as simple as T4, but it is possible to do it well.
It is also important to use symptoms and signs to determine when each T3 dose is due during the day – taking a T3 divided dose too early is just as bad as taking too much. The Recovering with T3 book has a T3 dosage management process, designed to determine only the amount of T3 needed to regain good health and no more than this. Symptoms and signs often show patterns over the day, usually, it is possible to spot these if tracking is done before and a few hours after thyroid medication doses. The patterns of change in symptoms and signs are incredibly helpful in determining an optimal T3 dosage. The Recovering with T3 book goes into detail on this. See the blog post list below for much more detail on how to track symptoms and signs.
Until thyroid researchers develop new laboratory tests of how well thyroid hormone is regulating the function of our cells, the use of symptoms and signs is the only reliable way of managing the dosage of T3-only replacement.
The Recovering with T3 book emphasises safety and caution. The T3 dosage management process which is described in detail within the book, allows the patient’s T3 dosage to be determined safely and effectively. I continue to hope that over time some of the more open-minded doctors and endocrinologists will read it and find some value in it also.
See this blog post for more details on using signs and symptoms:
https://paulrobinsonthyroid.com/tracking-thyroid-symptoms-and-signs-vitals/
Best wishes,
Paul
(Updated in August 2022)
Good Afternoon Mr Robinson,
I am on a T3 only protocol but on a very high dose with no signs of over stimulation, none.
I am wondering if there is a good brand of Cytomel. I have found that there are about 8 distributors in the US but I am wondering if any brand is better than another. Thank You for your content, it has helped me so much.
Hi Gail, I think Cytomel is pretty good. However, I usually advise patients to join a thyroid forum and ask other patients who are in their country to comment based on experience with actual brands. Getting personal feedback from people who have actually used the meds is often the best way to go.
If you are on T3 only then I do recommend reading my Recovering with T3 book – it is the safest approach for using T3.
Best wishes, Paul
Hi Paul
After 10 years of hell after a TT trying to get meds, doses etc right, I am finally pretty settled on T3.
Your information and advice has helped enormously where other attempts to get on to T3 have failed.
I am currently taking 40 mcg in two doses which I now know, having read your work, is not enough. I have my first dose (20 mcg) at about 7 am. At 3 pm I begin to feel tired and I invariably nod off between 3.30 pm and 4 pm. I have the second 20 mcg at about 8 pm and sleep heavily through the night.
As I write this, I can see that it’s wrong. When I was post TT I had the standard therapy of 3×20 mcg and was fine with this, although on hindsight, 50 mcg would have been better. I did lose a lot of weight.
I now want to do as you advise and multi dose. My thoughts are: 20 mcg at 7 am, 10 mcg at 3 pm, 5 mcg at 7 pm, 5 mcg at 10 pm.
I want to titrate up to 50 mcg. I have a source for Tiromel 25 mcg which I thought I could use in the titration to 45 mcg. I thought of splitting that into 3 and having a first dose of 18.5, second dose 10 mcg, third dose of 5 mcg, bedtime dose 10 mcg. Or thereabouts, depending on response.
I could have sorted myself years ago with T3 – had I not been led astray by fanatics on a well known forum who insist that one daily dose works better than divided doses and a fear of what doc/ Endo will say if I exceed the sacred range – which cannot of course exist for T3 only.
I’d be grateful for any comment Paul – and thank you for all you have done for people whose lives have been wrecked by thyroid issues.
Kind regards
Maureen
Hi Maureen,
If you are starting to feel tired by 3:00 pm you should be tracking signs as well as symptoms during the 3-4 hours prior to that. You should see some changes in body temperature and other signs that correlate with the increase in tiredness. My guess is that you’d likely need a second dose of T3 much earlier than 3 – perhaps noon or 1. Getting that dose in early enough will enable it to absorb and reach the cells and begin to work so that the tiredness never occurs. I suspect 10 mcg may not be enough for that dose but you’d have to check the response in signs and symptoms.
As for 5 mcg T3 doses. I have found that most people do better with doses that are larger than this. So, if, say you need a 10-15 mcg second dose at noon or 1, you may find through symptoms and signs tracking that you need another dose at 5 or 6 pm.
One daily dose can work for some people but many (IMHO ‘most’) find that multi-dosing is far more physiological – providing the cells with occasional bursts of necessary T3 rather than trying to super-saturate them with a Supra-physiological amount in one go.
Thank you for the nice comments too!
Best wishes, Paul
Hello Paul, I bought your book a three years ago when I started a trial of T3 but can’t lay hand on it today.That trial was discontinued due to a change of doctor. I’ve never got on with T4 only I’m now seeing a very experienced consultant endo who has shifted me first from 130 mcg levo only to 20mcg T3 at 8am and 1pm plus 25mcg levo at bedtime. its been pretty life changing but i was having a drop off later in the day about 5-m. He suggests going onto t3 only and adding in a further 10mcg T3 at about 5pm or 6pm. I’m a bit freaked out about stopping T4 altogether (its like a useless but familiar comfort blanket). Does the suggested dosage regime sound sensible to you? He says we could go to a max of 20mcg T3 three times a day. What are your thoughts? Mike
Hi Mike, if the ‘drop off’ in symptoms occurs around 5 pm then another T3 dose around 3 pm or 4 pm ought to really help that.
I’m not sure how your endo decided that ditching 130 mg of Levo might be equivalent to 10 mcg of T3, as I suspect you would need more than 10 mcg of T3 in order to fix the ‘drop off’ and carry you through the rest of the day. Maybe, he sees this as just a start.
Overall, if he is prepared to go to three doses of 20 mcg then I guess he envisions the switch over to 25 mcg T3 = 10 mcg T3 is just a start. If there is good evidence that you don’t convert T4 very well then it sounds like an ok plan as long as you will be able to increase the T3 quite quickly if you feel more hypo as the T4 clears.
I’d get another copy of Recovering with T3 if you can’t find your original – it seems like you may need it.
Overall, your endo sounds quite enlightened – so I would be encouraged to be honest.
Best wishes, Paul
Thanks Paul, I’ll get looking for wherever I left your book in a hypothyroid brain fog. I probably wasn’t clear. Thank you for the advice. The endo has already dropped my T4 to 25mcg and introduced T3 at 40mcg split in two doses (8am and 1pm). Next part of the plan is to remove the last 25mcg levo and introduce a further 10mcg (or 20 if necessary) in the late afternoon . So a daily total of 50 to 60 mcg T3 and no levo. And yep I’m lucky to get such an enlightened endo after long grueling years of trying to get well on T4. I have the genetic polymorphism that’s been linked to poor intracellular t4 to t3 conversion so that along with five years of poor outcome on levo informed his approach I think.
Sounds good!
Good luck Mike!
Hi Paul!
I’m starting out on T3 only this week. I am what you would call a “complicated case” with my health in general. I can barely eat (300-600 cals / day) and I am severely dehydrated (cannot tolerate electrolytes whatsoever). A full thyroid test panel shows that I am pretty hypothyroid (probably due to all the inflammation). I haven’t been able to “move forward” on anything at all – I’m hoping that supporting my thyroid with T3 might help my basic body processes work at least a little better! Do you have any advice for someone so “fragile” as me?
Thank you 🙂
Jaden
Hi Jaden, no, I am afraid I don’t have any insight. Your situation sounds as if something beyond thyroid hormones is going on.
I would thoroughly test cortisol levels with a 8-9 am morning blood cortisol test and a saliva cortisol test (4 samples). Plus iron, ferritin, B12, folate, and vitamin D.
Low glucose levels due to lack of food intake, plus low iron, cortisol B12 etc. can all make tolerating T3 very difficult. So, you would need to go very slowly with very low doses.
But generally, no, your case sounds very difficult. I hope you have good medical support.
Best wishes, Paul
I hope this is how to contact you, Paul.
I am 81 and due to many years of working with lyme and coinfections I gravitated to needing 30 mg of hydrocortiosne.
The lyme and coinfectiosna nd mold are much less a factor now.
I am on T3 only and am scared because my fasting (15 hours after my last T3 dose at 6:000 PM) is only 1.7 and my T3 dose is 80 mcg.-35 mcg at 8:30, 30 mcg at 1:00 and 15 mcg at 6:00 PM.
I have no hyper symptoms and my pulse is 60. and my Rt3 is 38. and my weigh is steady, BP 120/78
I have periods achenes s but this is when my cortisol is low (sometimes I need a bit more cortisol if stressed).
Based on my FT3 being as low as 1.2 on 60 mcg I project that I will need 160+ mcg of T3 to get to 3.5.
I have not read your book in several years but I believe you are not concerned about labs because the FT3 is usually in range or higher.
Of course, my FT3 is so low.
My iron is only 72 and I am working on increasing it.
Have fatty liver from the hydrocortisone and maybe low thyroid because do not drink and limit my carbs to 60 grams.
Am thinking somehow the RT3 is effecting my FT3. I realize you say it is an indirect effect.
I would feel a lot more calm about continuing to increase my T3 if you can tell me that other patients have needed 160 mcg or more of T3.
I doctor/friend want me to switch to sloe release T3 but I recall you do not like sloe release t3?
Yes, I realize I need to look at signs and symptoms and I need to chart my temperature (I can get cold.
Hi Robert can you please restate your thyroid labs but add in brackets after each what your lab reference range is please. They vary so much by country and lab that I have no idea how to interpret without these. Plus please be clear what thyroid meds you are taking – and if you also take T4 meds. rT3 only gets made from FT4. So I’d need to see FT4 and the lab range too. On 80 mcg of T3 only there should be no FT4 and no rT3 so either you are on T4 or have something strange going on – TSH should also be suppressed and not requesting your thyroid gland make any T4. Either this OR your T3 tablets are duff. I’ll wait for the labs. Thank you.
You might also need to be using CT3M – but this won’t work if the T3 is duff.
Have you read The Thyroid Patient’s Manual book and Recovering with T3 – I would they will both help.
Best wishes, Paul
Robert,
You can also just use my email: paulrobinsonthyroid@gmail.com – I would need the reference ranges edited into your message to me.
Thanks. Paul