Interpretation of Signs in The Circadian T3 Method (CT3M)

Thank you to Darin Gregg, Joanne Irwin and other old my old thyroid forum members who contributed with comments and support during the process of putting this information together.

Interpretation of Body Temperature, Heart Rate and Blood Pressure (Signs) When Using The Circadian T3 Method (CT3M)

This post assumes that the thyroid patient has low cortisol, but that there is no Addison’s disease or hypopituitarism. It is designed for the simplest case of someone who responds straightforwardly to the CT3M.

Essential Tests

Thyroid patients should not attempt to use the CT3M unless they know with confidence that they have low cortisol.

Many thyroid patients who have been ill for some time and have not simply bounced back from thyroid treatment will indeed have low cortisol. It is also common for patients with Hashimoto’s thyroiditis to have less than ideal cortisol levels. Even so, low cortisol should be confirmed by laboratory testing. This can only be achieved with confidence if a 24-hour cortisol saliva test and an 8:00 am morning cortisol blood test have been done. In addition serum iron, serum ferritin and transferrin saturation % should also have been tested. Ideally, B12, folate and vitamin D will also be tested. Iron and cortisol must be tested prior to starting to use CT3M and to start without these may waste a significant amount of time and cause incorrect actions to be taken.

There must also be no Addison’s disease or hypopituitarism as both of these conditions will not respond to the CT3M. If there are any issues with blood sugar balance, e.g. diabetes, pre-diabetes or insulin resistance, these also have the potential to get in the way. 

General Observations

High and low cortisol can both cause thyroid hormones to be rendered less effective. High cortisol can block the effect of thyroid hormone and low cortisol will reduce the flow of glucose from the bloodstream to the cells and also make thyroid hormone less effective (due to the adverse effect on ATP production and because thyroid hormone works synergistically with cortisol). Why mention this? Well, it means that when applying the CT3M it is very easy to be confused if you don’t know if cortisol is high or low. Guessing about cortisol is not a good idea.

If cortisol is very low and the circadian dose is increased or moved earlier this can cause  a worsening of symptom and signs. So, there may be a need for trial and error and careful thinking at times. The guidelines in this post are really just a starting place and will not cover all cases and all patients’ needs. It is often better to discuss the symptoms and signs that are being experienced with your doctor or other thyroid patients to get more input.

We have also found that it is important to start with low levels of daytime thyroid medication to avoid problems. If a thyroid patient has found out about the CT3M but is already on a high T3 dosage, e.g. 80-120 mg of T3 but they report low body temperatures, feeling cold and tired they almost certainly have more than enough thyroid hormone. The symptoms and signs could be due to low cortisol, or the overwhelming high level of T3 that is somehow causing problems.

Time and time again we have seen symptoms and signs that suggest hypothyroidism that have been caused by excessive use of T3. The problems get worse when someone like this begins to use the CT3M, as all this excess thyroid hormone may begin to be effective. We often see body temperature, blood pressure, and heart rate all shoot up dramatically, as well as other symptoms that suggest hyperthyroidism.

Problems can also ensue if a patient reduces their daytime T3 dosage, whilst already doing the CT3M, as this also can make more of the thyroid hormone effective and balanced with the cortisol availability. To avoid this we believe it is essential to start with low daytime doses of thyroid medication (T3 or natural desiccated thyroid) to reduce the risk of this happening.

So, with all of the above in mind let us make some simple and general observations.

General Guidelines on Signs in The Circadian T3 Method (CT3M):

Lowered BP, Temps, and HR over the day often indicate low T3.
– This may be accompanied by a greater sense of pain, if you have pain issues (muscle and or joint pain), tiredness, lack of motivation, brain fog, and anxiety. The full list of hypo symptoms is extensive.

Higher BP, Temps, and HR over the day, often indicate too much T3.
-This may be accompanied by shakiness, wired anxiety, agitation, weakness, spacey feeling, brain fog, muscle tightness (pain in neck, headache) and/or feeling physically overheated, among a host of other symptoms, which can indicate too much T3.

Note: Too much T3 can manifest with higher systolic (top number) BP, with diastolic perhaps remaining the same or only slightly raised. Too much T3 usually raises the heart rate and makes someone feel warmer (but this depends on whether there is enough cortisol and iron etc.). Anxiety and a feeling of tension/stress can also be caused by too much T3 as can loose bowels. See the ‘Recovering with T3’ book for more information on the affect of excessive or too little thyroid hormone.
Temperature Guidelines:

Lower than normal temps < 98.4F average, is indicative of low thyroid hormone levels, and >99F average, is indicative of high thyroid.  Temps may start the day lower, but average should be 98.4 – 98.6F.

Basal temps below 97.8F (true basal temp can be as low as 97.4 and still not mean hypo (it needs to be averaged over a 3 to 5 day period), can be indicative of low thyroid, but basals are not the best indicator. 
Note: Basal temp is the body temperature taken first thing when you awake, before getting out of bed.

Taking Temps: We need to assess the success of the circadian dose. So, taking the temperature within the first hour after rising is essential. A mid or late morning and mid/late afternoon and evening reading is also useful.

Repeating these at the same times each day is important so that a comparison can be made and any trends spotted (the same applies to heart rate and blood pressure readings. Several days of readings may be needed to draw any real conclusion.

For natural desiccated thyroid users, taking an average daytime temperature, i.e. averaging the morning, afternoon and evening body temperatures may be more helpful.

For T3 users: Temperatures should be taken within the first hour of rising and then in between each T3 dose and just before the next dose is taken as well as sometime in the evening. Taking temperature in between each dose provides information on whether the previous dose was effective. Taking the temperature just before each dose is taken provides information on whether the dose that is about to be taken is actually needed yet or not (if the vital signs are still good then maybe the dose should be delayed). No averaging of these temperatures for T3 users should be done, as each T3 dose should be assessed in terms of its affect on body temperature.

Note: Temps can drop if you are very relaxed, sleepy (taking a nap), without being low T3. Everyone has had this experience, but when you get up and do something, temps rise again.  At least one other symptom of either hyper or hypo should go along with the temp fluctuation before using temp as a dosing guideline.

Heart Rate Guidelines:

Heart Rates <60 and >90 BPM, are often indicative of low and high thyroid respectively, but there are individual variations. Anything below 66 is suspicious of hypo, unless you are an athlete and very fit, in which case you can have a much lower than normal HR without symptoms. Normal HR for an average person is in the 70-80 range. Exceptions to this rule: High HR or high normal, with lower temp and BP may be an indication of hypo. (HR should fall, BP and temps may rise after dosing)

Low HR or low normal, but raised BP, and lower temps, may be an indication of hypo. (HR should rise, BP may lower a bit, and temps may rise after dosing)

High HR, with raised BP may be an indication of adrenaline production due to low cortisol. In this case, temps may be low, normal or even high. In this case the heart rate is often well above 90 and the BP much higher than normal.

Feeling as if the heart is pounding with normal BP, HR (beats per minute) and temp, could indicate you need electrolytes such as magnesium/potassium /calcium or any combo of those. A fast pounding heart rate can be low sodium. A slow pounding heart with low (or raised) BP and (low) temps could indicate low T3. A pounding heart can also be the effect of adrenaline due to low cortisol (this is often accompanied by raised BP but it depends on how low the cortisol is and how high the adrenaline is).

Note: The late Dr. Lowe said if all vitals seem normal, a mild pounding sensation, could be a sign of adequate thyroid, as thyroid patients aren’t used to the normal healthy heart beat.

Other Observations:

Patient Joanne Irwin’s experience with dosing—“I am finding that if I wake with my temp lower than 97.6 and it does not get to 98.4 by 1:00 pm (for a couple days in a row), I need to add a little (2.5 at a time) to the CT3M dose the next day, or to my 10:00 am dose. I try to get the temp up to (no less than) 98.4 by 2:00.  My temps, BP and HR all seem to line out great if I go by this timing of temp readings”.

In addition to all the above it is very important to look at trends and changes that have occurred due to thyroid medication dosage changes.

Often the most important information is in fact to be found by assessing a number of different changes in circadian dose or daytime thyroid medication dosage that has caused changes in symptoms and signs to occur.

Very often just looking at heart rate, temps and BP alone at any given time will not be enough to assess what should be done to improve adrenal function and symptoms and signs. It is the overall assessment over a number of dosage changes that will reveal a clearer picture of what is occurring.

Finally, repeating laboratory testing of cortisol and iron and other nutrients may also be required to provide sufficient insight into what is happening with thyroid hormone and cortisol levels.

Best wishes,


(Updated in January 2019)

Paul Robinson

Paul Robinson is a British author and thyroid patient advocate. The focus of his books and work is on helping patients recover from hypothyroidism. Paul has accumulated a wealth of knowledge on thyroid and adrenal dysfunction and their treatment. His three books cover all of this.

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