I was asked recently to explain my views on the relationship of the T3 thyroid hormone to Cortisol. This is an easy question to ask but an extremely complex one to answer. It is difficult to answer questions like this in an email or on a forum and provide a good enough understanding in order for the person to make really good decisions.
My books are definitely the best source of information that I have to offer to thyroid patients about the relationships between T3 and Cortisol.
I write about this topic extensively in all three of my books:
The Thyroid Patient’s Manual, Recovering with T3 and The CT3M Handbook.
My website blog also has numerous articles that cover various aspects of this subject and it is very searchable. I recommend searching for any word or phrase that you think might be relevant to what you are interested in, e.g. ‘cortisol’, CT3M’, ‘T3 and cortisol’ etc.
However, I have received numerous requests for a brief summary of the important relationships between T3 thyroid hormone and Cortisol. I have put these in bullet point form in this blog post.
Some important T3 thyroid hormone and Cortisol relationships:
1) Cortisol and T3 are partners. T3 and Cortisol both need to be at good levels. Cortisol increases T3-effect, and T3 increases cortisol-effect – they are in a partnership within the cells. They both work at the mitochondria and at the cell nuclei and are essential in the production of proteins amongst other things. In addition, one of cortisol’s roles is gluconeogenesis. This converts stored sugars into available sugar in the bloodstream in between meals. Glucose (blood sugar) is needed by the mitochondria in order to produce cellular energy (ATP). Assessing glucose levels is an indirect way of assessing cortisol levels. It is not the most definitive way, but it can help when trying to get cortisol optimal. Note: adrenaline also mediates gluconeogenesis.
2) The pituitary gland controls cortisol production via the Adrenocorticotropic Hormone (ACTH). ACTH stimulates the adrenal glands to produce both cortisol and Dhea. Without enough ACTH, cortisol production by the adrenals will be too low.
3) However, studies show that the pituitary gland needs more T3 than any other organ in the body. The pituitary basically runs using T3 as its fuel. This makes the pituitary vulnerable to not working well if T3 is low. This is fundamentally why low cortisol is so prevalent in thyroid patients. Many thyroid patients are on treatments that do not give them sufficiently good T3 levels. It is such an obvious conclusion. Poorly treated hypothyroidism (low T3 levels), often results in low cortisol.
4) Adrenal Fatigue is a bit of a myth. Adrenals do not usually get ‘tired’ or ‘overworked” unless they are damaged by disease or autoimmune attack – i.e. Addison’s disease. Usually, the issue is the lack of enough pituitary signal (ACTH).
5) The pituitary can fail to produce sufficient ACTH signal to the adrenal glands because of hypopituitarism (which can be tested for) or simply because it is not receiving enough T3 thyroid hormone (see point 3). Many other issues can cause the hypothalamic-pituitary (HP) system to fail to regulate the adrenal glands with sufficient ACTH at all times over the day.
6) T3 is more likely to stimulate cortisol production than T4. T3 helps to keep cortisol levels up as it stimulates the hypothalamic-pituitary system more than T4. This latter point is why thyroid medications that contain T3 often help to keep cortisol levels higher.
7) Low cortisol is very common in thyroid patients, as many have lower T3 levels than they had when they were well (for reasons I have discussed in my books and in various other blog posts).
8) Cortisol is not required for T3 to be able to enter the cells. T3 enters our cells through transporter molecules and these do not require cortisol to function. Therefore, there is no evidence that low cortisol causes T3 ‘pooling’ or ‘build-up’ or inability to enter our cells. In fact, new research as of 2021 proves the opposite is true – high levels of cortisol actually inhibit T3 transport into the cells, whereas low levels do not. See this blog post for more details, including a reference to the new research:
paulrobinsonthyroid.com/high-low-cortisol-effects-on-thyroid-hormone-and-dispelling-an-internet-myth
9) Low cortisol causes T3 to work less effectively within the cells. This is because T3 and cortisol are partners within our cells. High cortisol also causes problems and can reduce the effectiveness of T3 within the cells, hence thyroid patients with high cortisol often complain of feeling hypothyroid even when they appear to have reasonable FT3 levels.
10) When patients try to raise T3 levels in the presence of low cortisol, they may find that the body compensates for low cortisol by producing more adrenaline. This can cause anxiety, rapid heart rate, the feeling of heart palpitations etc. This is usually the adrenaline response rather than a direct issue with the T3. Very often, it is the low cortisol that is at the root.
11) When cortisol is low, taking daytime T3 is often enough to correct it. However, it sometimes also needs nighttime dosing of T3. See my Circadian T3 Method (CT3M) protocol in the Recovering with T3 book. CT3M is also covered to some extent in The Thyroid Patient’s Manual and in detail in The CT3M Handbook.
12) Cortisol dysfunction patterns are numerous. Often there is low in the morning, rising to high in the evening due to the pituitary being very slow to catch up. Sometimes there is low all day. Sometimes there is high cortisol due to the strain of low T3 and high rT3. In many cases, if the person is hypo, getting the T3 levels up without high rT3 can help. Sometimes it needs CT3M. CT3M can help with many patterns of cortisol dysfunction – not just low morning cortisol.
13) Low cortisol is a serious issue for thyroid patients. It is important to rule out Addison’s disease by having the appropriate ACTH Stimulation test done (also known as a Synacthen test). This can only be done under the supervision of a qualified endocrinologist. Addison’s disease can be life-threatening and any thyroid patient with low cortisol needs to have this tested for and ruled out.
14) If Addison’s disease is diagnosed then cortisol will need to be replaced and this is likely to be a life-long requirement. This should be done under the supervision of an experienced endocrinologist. There are many alternative medications and approaches to cortisol replacement. If one solution does not work, another may be tried. Some endocrinologists are far more experienced with various solutions for cortisol replacement than others. So, finding a specialist who is knowledgeable and experienced is very important when cortisol replacement is needed.
15) Some Addison’s disease patients are finding that when cortisol replacement is needed that only a cortisol pump replaces cortisol in a physiological way. Search my website for ‘cortisol pump’ to find out more. Replacement with cortisol is a serious step and it does need an extremely competent endocrinologist to help with this.
16) Hypopituitarism can also result in an insufficient ACTH signal to the adrenal glands. This too may be tested for (see The Thyroid Patient’s Manual book for some of the possible tests). There are various tests for hypopituitarism and these can also be organised by a competent endocrinologist. If hypopituitarism is present then replacement of cortisol is also likely – see points 13 and 14.
17) However, most causes of low cortisol are not as serious as Addison’s disease or hypopituitarism. Correcting hypothyroidism may frequently resolve any low cortisol issues. Hence the need to be aware of the potential connections between T3 and cortisol.
18) Many thyroid patients who have low cortisol, or have the symptoms of low cortisol, are often persuaded to try to raise cortisol by various methods. Some are told that herbs known as Adrenal Adaptogens will work. However, these often lower cortisol levels (herbs do not have brains – herbs cannot work out whether to raise or lower cortisol for the individual). Some patients are persuaded by doctors or other patients to try to use either hydrocortisone (bio-identical cortisol) or adrenal cortex extract from animals. These types of approaches are a mistake if the problems are really connected to low T3 levels or some other issue that needs to be addressed, e.g. low B12, low iron etc. I would always want to explore other solutions for low cortisol before resorting to any form of cortisol replacement, as this switches off the individual’s own cortisol production ability.
19) The effects on temperature, BP and heart rate of cortisol and T3 can be far more complex than the simple explanations that are often used on Internet websites and forums. Low body temperature may come if either T3 is low or cortisol is low. However, if cortisol is very low for the person, then adrenaline may be produced to compensate and raise blood sugar, and this might actually raise temperature to a better level. In that last case, the adrenaline might cause a high heart rate and elevated BP. It is never as simple as people think. High BP can come from high cortisol, excess adrenaline from very low cortisol, or too much T3. This is why understanding the thyroid system and how it works with cortisol etc. is so key. I have tried to explain this as best I can in both The Thyroid Patient’s Manual book and the Recovering with T3 book. These are just examples. Reading the books mentioned above will help.
20) If cortisol is low and if the thyroid treatment is not optimal then adjusting the thyroid treatment can work wonders. Improving FT3 levels in the daytime can improve cortisol levels. This often involves increasing the amount of T3 in the treatment. Sometimes rT3 and Ft4 needs to be lowered in order to allow T3 to work better. Improving daytime T3 levels are often enough but some people with low cortisol that are due to low T3 need more help than this. In some cases, the FT4 and rT3 really need to be reduced a lot. In some cases my CT3M protocol needs to be used.
Finally, I emphasise again that The Thyroid Patient’s Manual book is a good starting point to learn about the thyroid hormone and cortisol systems. Recovering with T3 is next and covers the safe use of T3 and of CT3M if it is required. My website blog is very searchable and useful too.
I would advise against relying mainly on Internet forums – mine included. Building a more comprehensive knowledge base is always the best thing to do. Once you understand how the important systems of the body actually work, then it is possible to make sense of things. Hence, I recommend reading my books. Clearly, finding a knowledgeable doctor or endocrinologist that you can work well with can be very important to regaining your health. Be prepared to switch doctors, or keep looking for someone who you can work with – it can help a great deal.
I hope this is helpful.
Note: I have five blog posts (including this one) that cover the relationships between thyroid hormone, cortisol and sex hormones:
https://paulrobinsonthyroid.com/cortisol-results-inconsistent-between-saliva-testing-and-blood-testing/
https://paulrobinsonthyroid.com/t3-thyroid-hormone-and-cortisol-relationships-summary/ (this post)
https://paulrobinsonthyroid.com/sex-hormones-and-cortisol-relationships/
https://paulrobinsonthyroid.com/estrogen-dominance-the-use-of-progesterone-and-high-adrenaline/
Best wishes,
Paul
Hi Paul, Do you happen to have any articles/insights re: 1. undiagnosed or untreated ‘subclinical’ hypothyroidism (3.4 TSH) and how this effects menopause, and, 2. the effects of low FT3/mid-low FT4 on blood sugar regulation? 2 years into menopause. When I started using bi-est 1.25 with 20mg progesterone so many symptoms resolved except I felt cold all the time. When I stopped using BHRT for a dexa challenge to test cortisol because morning blood sugar was high despite a 5.4 A1C, I had high or 3 points above range morning cortisol. This is in part explained by hypoglycemia episodes as I wear a CGM to track. Interestingly, or not, I had a strange reaction to dexa 1 hour after taking it i.e. woke from sleep with a severe anxiety-like attack. MD said this wasn’t of concern. I re-started BHRT thinking this was needed due to brain fog and lack of energy/motivation (working professional), inability to lose weight despite focused effort on diet and exercise to do so, worsening fasting glucose, and now my cortisol appears to be on the low end based on low blood pressure and BHRT isn’t improving any symptoms. So, on a hunch, based on historic lab results for TSH: 1.8 / 2.6 / 3.4 (progressively worse) I am trying NDT and feel better, warmer via checking temps, severe nail ridges on hands and feet are going away, eye puffiness going away. Curious, does menopause without using hormone replacement ‘unmask’ hypothyroidism? Is hypothyroidism the real culprit behind why some women have such a difficult time in menopause vs. others? Love your comment re: adaptogen herbs…they don’t have a brain!
Hi Sandra,
Having hypothyroidism won’t help someone who has sex hormones that are already too low during menopause. It is unlikely to be the reason for going into menopause but it certainly won’t help.
All I have to say on this subject is contained in a chapter in my The Thyroid Patient’s Manual book plus in this blog post you have commented on.
I haven’t got any other links, sorry.
Best wishes, Paul
Paul,
I have T3=2.2gp/mL and below lower limit on morning cortisol, otherwise I am health, 84 years old.
I have symptoms of low cortisol.
Any thoughts?
Thanks,
Jim Lee
Hi Jim, I don’t know what your lab range is for FT3 – it varies a LOT by lab and country.
If FT3 is low then this can cause lower cortisol than normal for the person.
Best wishes, Paul
Hi Paul
Until Christmas 2022, I’d been on 2 grains of NDT for about 5 years with very few problems.
In January, blood results showed that while my FT3 remained at 5.9 – usual level – my FT3 had dropped from 18 to 13. I was feeling very tired and unwell. High BP and low heart rate. Sometimes I felt that my heart had actually stopped and waking up in the morning was like emerging from a coma. Clearly my cortisol was very low and this had been seen in a saliva test the year before.
Under intense psychological stress and emergence and dx of peptic ulcer disease – still unresolved – and diverticular disease and generally unwell.
Decided to replace with 40 mcg T3 which I had used successfully many years ago. Tiromel ?? Gradually dropped NDT and replaced with T3 by titration over 6 weeks. Perhaps I didn’t give the T3 long enough but I still felt undermedicated even on 50 mcg. I would expect at this dose to have some indication of the beginnings of overmedication. Not so.
I then decided that I felt better on NDT and am fighting to get back to my 2 grain dose. Reduced the 50 mcg by 12.5 mcg and introduced I grain of Thyroid S. This two weeks ago. The website I took advice from advised after two weeks, I should reduce by a further 12.5 mcg, hold for two weeks and then add in the second Thyroid S. it was advised that by then the T4 in the Throid S should be sufficiently high to remove the penultimate 12.5 mcg T3, hold for a week or two and then drop T3 altogether.
Not feeling happy about this and tempted to go back to T3 only but my sense tells me not to chop and change.
Alternate between very cold and hot flashes. Very tired. Can’t cope with anything. Thought about raising NDT to 2.25 mcg but last time I did that (3 years ago) I had symptoms of over medication – high FT3 etc.
Concurrent meds are opioid patches for pain and Duloxetine for pain. PIL in Duloxetine advises that it can affect thyroid meds. Don’t know whether this is via skewed tests.
Would appreciate your advice.
Many thanks
Maureen,
This is complex and I suggest you use the Contact Us page on my website to reach me by email.
Your second paragraph also states FT3 levels twice but I think the second reference means FT4. If the FT4 dropped on the same NDT dose then either the thyroid gland itself has finally atrophied and failed to add T4 or absorption in the gut has deteriorated for one reason or another. There isn’t much of another explanation unless the brand of NDT has suffered some manufacturing issues.
Chopping and changing never works especially when T4 is involved it takes 8-12 weeks for a T4 medication adjustment to fully work.
Also, don’t guess on cortisol – do BOTH a morning cortisol blood test (8 am or 9 am) and a 4-point saliva test.
I distrust any site that suggests rigid increments of any hormone ever few weeks – we are human beings, not robots.
Use the Contact Us – too complicated for here.
Best wishes, Paul
I’m confused, you share raising T3 raising raises cortisol, but in my experience, T3 has the opposite effect on me. It’s been 15yrs+ of not sleeping. I realized I would sleep 2-2.5 hours after taking my thyroid dose, every. single.time. I recently decided to see what would happen if I kept taking doses every time I woke up, could I for the first time ever get 6hrs sleep? This to me suggests it lowers my cortisol to allow me to sleep. I have very high Free Cortisol and Very Low Cortisol Metabolism measures. Not sure if that offers any insight…. I usually felt like I was extremely wired tired adrenaline like until I crashed after a couple weeks. Now, since upping night time doses and sleeping, I have no adrenaline feelings, just tired and depressed… feeling it all I guess. So in reference to what you share, why is it that now I am taking more T3 spread out (every time I wake up) and for the first time in decades I can get 6hrs sleep? I do wake up every 2 hrs to take it which isn’t ideal. I will try a delayed release T3/T4 but suspect it wont be enough T3 with the delayed release vrs slow release capsule (which is all at once in small intestine I think). Would love your insight!
Nico,
Let me say to begin with that I am very sorry that you’ve had 15 years of sleep deprivation. That must be very difficult for you.
People never actually test cortisol during the night when they are either sleeping or staying awake. Since free cortisol and total cortisol changes a great deal over 24 hours it is very hard to actually guess what your cortisol is during the night – even if you’ve tested it in the daytime.
The fact that taking the T3 in the night is helping means that it could be working with the cortisol to use some of it up (and lowering it a little as you’ve suggested), but equally it could actually be raising cortisol (which is more likely in my view). Low cortisol in the night also causes severe sleeping issues. This is why for those with cortisol dysfunction, taking a CT3M dose of T3 (see the Recovering with T3 book – the definitive guide), often really helps people to sleep.
I also don’t know how much T3 you are taking. What I do know is that many people have success with a CT3M dose of T3 (often taken around 3:00am – just before the pituitary gland begins to start requesting cortisol production from the adrenals. This CT3M dose can be 10 mcg, and sometimes as high as 20 mcg of T3 and occasionally more. In addition, Simply taking too little T3 or using doses of T3 that are too small can also lead to low T3 in the night which in itself (regardless of cortisol levels) can lead to extremely poor sleep.
I don’t want to speculate more as I would need to work more closely with you on your actual dosing and on detailed testing of cortisol in order to have a better idea of what is going on. This website page is not a suitable vehicle for that though.
I do hope that you continue to make some progress with this as it sounds really difficult.
Best wishes, Paul
Thank you for your reply and feedback! I’ll do some more reading as suggested and if I can connect for further investigation, I will!
Side note: I did a Dutch test, 24hr dry urine collection and followed all the rules. It marked a regular rise and fall of cortisol throughout the day…. But the very high Free Cortisol combined with very low Cortisol Metabolism was noted.
Now that I’m sleeping (5mcg of compounded liothyronine every time I wake up, usually every 2 hours for a total of 15mcg), I’m dead tired all day without the feeling of wired tired adrenaline. It reminds me of my younger years before I had to push myself to the point of running off adrenaline/cortisol that interrupted sleep and maybe reinforcing the cycle. My existence has been, push myself to meet lowest standards of normal, then I can’t sleep from running adrenaline, get a migraine, take a migraine med and finally crash… and do that over and over.
Anyway, just discovered you so I’ll learn what I can!
Thanks!
That’s a very low dose of T3 – 5 mcg tends not to last long at all. It is even less potent if it is slow release.
I’d try bigger doses of T3 – perhaps before you go to bed.
I don’t know what you dose in the daytime but I can say for sure that low T3 levels do keep people awake. Doses often need to be quite high in the day to carry through the night 5-10 mcg doses just don’t cut it.
Good luck though Nico.
Best wishes, Paul
Thanks you so much for your thoughts! I’ll play with this. Hopefully I’ll connect with you 1:1 once I do some testing…
Good luck Nico!
Best wishes, Paul
Hi Paul
I have struggled with idopathic primary insomnia for over 20 years now, extremly fragmented sleep
My T3 is around 6,7 – 6,2 pmol/L, and morning Cortisol between 500-600
TSH 1,09 -1,4 mU/L
No doctor has at any time told me something is wrong with my thyroid levels, but still i suspect something is causing my insomnia
What are your thoughts?
BR Lars Jensen
Hi Lars, can you edit your comment and make clear what the results are with the reference ranges for your lab.
Is the result for FT3 (free T3)?
What is FT4 also?
Have you also tested B12 and folate (when not on any B12 at all for 4-5 months)?
It might be worth taking magnesium near bedtime also.
Best wishes, Paul
Having Hypothyroid symptoms , Could be from environment in a new house and area. , Endotoxins shows high in new house, Cortisol spikes, sooo – resulting inflammation from both.
After 3 months of symptoms had a test -T3 3.1–RT3 14.5– 2 months later another test as I got worse -T3 -2.8 and RT3- 25 are the out of range, Other thyroid labs are normal ranges even with the values used by homeopathic doctors…So clearly something happening. also Goiter forming , never had this 57yrs of age
Doctor wants to put me on Liothyronin to increase t3 and bring down rt3, ( And move from house) However Another dr says my adrenal glans are spiking cortisol and is worried that the Thyroid meds would be contradictory. I read in mayo clinic that taking this med wit adrenal insufficiency is not advised. (But my cortisol is at 15.5 ug/dl morning, and takes a mostly normal path of lowering until bed , sometimes with occasional spikes in the late afternoon), with adrenal issues , Your thoughts ..
Jeff, I would need to know if the T3 result is Free T3 or Total T3 and I’d need to know the reference ranges for each result as they vary by lab and country. So, I am not able to comment on the labs above.
T3 can be fine if introduced carefully as it can boost cortisol. Cortisol is often low just because FT3 is low. You won’t have adrenal insufficiency – you’ve have low cortisol due to low FT3 – very different.
You’ve contacted me via email for coaching so perhaps it is better to do that and have a detailed conversation then when you have all the lab test results that I use.
Best wishes, Paul
I have responded to Email Thanks Jeff
Hi Paul…newbie to your page. I’ve had Hashimoto’s since 1997. In 2006, I found a doc willing to prescribe NDT for me, and I have been on it ever since. However, in the last 2 years, I have been very ill–I visited my local ER twice last summer, but they practically laughed at me and threw me out as all my bloodwork came back ok. I thought I was suffering from some sort of adrenal issue because on a past saliva cortisol test, all my results were very low. Recently, I had an 8:30 a.m. cortisol blood test, result was 414 (range 140-535). I also had an ACTH blood test done, but at a different time as the cortisol blood test. The ACTH blood test result was 6.8 (range <14.0). Will these 2 tests, done at separate times (about 2 months apart) provide any info? I have had an antibody test for Addison's which came back negative. I am currently taking some adrenal cortex with breakfast and lunch everyday. Initially, I felt it helped but I'm not so sure anymore. Additionally, my endo has recently adjusted my meds, so now I take 120 mg/day NDT, 60 mg 2X day, and 5mcg liothyronine with a.m. NDT dose, and 5 mcg liothyronine with p.m. NDT dose. I have extreme insomnia, waking frequently during the night to go to the bathroom. Last night was 3 or 4 times! Am doing bloodwork next week, but FT3 and FT4 have both been low for the last year at least. I've been wondering if I need to switch to separate T4 and T3 meds, but I'm not sure about that. My only RT3 test was at 12 (sorry I can't find the test to see the range) but I remember that it should be lower than 15 in this range). My doctor said it was a good result for RT3.
Nancy, I am sorry that you are having issues.
It sounds like the doctors have not managed to assess your situation well enough and provide the right treatment.
The ACTH blood test is of little use.
People usually have to focus on FT3 – this is the active hormone and it needs to be good in the range without high FT4 or high rT3. Too much T4 and too low an FT3 level can cause many issues. Having Ok rT3 is still no use if FT3 is not at a good place in the range for you without high FT4.
My books are very useful but I do 1-1 coaching if you need detailed help. My coaching information includes the lab test results that I use.
Best wishes, Paul