I have spent the last month experimenting with how to measure temperature for thyroid health reasons. It’s not easy, we are apparently looking for a core body temperature accuracy of 0.1c, a tenth of a degree, to gauge our metabolic rate. I have posted below the result of this work so far for anyone interested, and what I have found that does not work. I will later post methods that do work.
One point to note above all, if someone mentions a thyroid temperature without stating exactly how it was measured, ignore the information. In this business there are multiple ways to measure thyroid temperature incorrectly all giving different and inconsistent results. There is only one way to get accurate and consistent results and that is with the Broda Barns technique.
To reiterate, any thyroid temperature measurement or temperature range you see mentioned anywhere that does not explicitly reference the Broda Barns, should be ignored completely.
By “thyroid temperature” of course I don’t mean the temperature of the thyroid, it’s shorthand for a core body temperature measurement, taken to monitor thyroid and adrenal health.
Thyroid temperature measurement techniques that do not work:
A.Ear thermometer
I have used a Braun ear thermometer for 15 years with great results and was sure it would work fine for measuring thyroid temperature. I was wrong. It is simply not accurate enough. I was expecting that ear temperature would be higher than arm temperature, and that there would be a constant difference between the two.
This is not what I found, while the ear temperature was higher, the difference was not constant, varying between 0.1c and 0.9c for the same axillary (arm) temperature. We are looking for an accuracy of 0.1c so this random difference effectively means that an ear thermometer is no use for thyroid temperature measurements.
However this does not mean that the ear thermometer is useless in general, it is an excellent and fast fever thermometer, especially for children, which is what it is designed to do.
To be clear, the ear thermometer does appear to be accurate, it’s just that it does not seem to be measuring core body temperature, which is what we are interested in, to determine our metabolic rate.
B.Mouth thermometer mercury or digital
A mouth thermometer, whether it be a mercury type, or digital, have the same problems as the ear thermometer they are not accurate enough for thyroid temperature measurements.
C.Forehead Digital thermometer
Forehead thermometers are designed to allow contactless measurement, and are excellent fever thermometer for mass screening and also for checking on sleeping children. However they are not accurate enough for thyroid temperature measurements.
D.Forehead strip thermometer
Useless for all purposes.
E.Axillary (under arm) Digital Thermometer
A digital thermometer used axillary, ie under arm, used according to the manufacturers instructions is inaccurate and misleading, being too low by over one degree, and should never be used with this technique, even for fever measurements, never mind for thyroid temperature measurements.
I suspect that a lot of low temperature readings reported by people are inaccurate because they were using the manufactures’ incorrect technique.
However I have found a way to measure axillary temperature accurately using a digital thermometer, it is slow but does work. I will mention it in another post.
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I’d be interested in seeing how to measure under arm with digital thermometer
I have been taking oral temp with digital thermometer and taking away 0.5c as this was the advice given on stop the thyroid madness . Would you even say that this is incorrect information? I must say my temp does fluctuate a lot which I’ve found odd .
Yes my experience is that it is inaccurate, the problem is that we need to be accurate to about 0.1c to get a good picture of what's happening. I found that the Arm measurement to be the most accurate but it is slow. Oral or ear are quicker and easier, and if there was a fixed adjustment to convert form one to the other they would be ideal. But I found that the amount they differ form the arm measurement varies from day to day from 0.1c to 0.9c with no pattern, making accuracy to 0.1c impossible.
I am working on a description of how to do the arm measurement and will post in a few days, it's basically the Broda Barns approach with a few notes on what to do with digital thermometers.
taking away 0.5c as this was the advice given on stop the thyroid madness .
The actual words I can find on Stop The Thyroid Madness are;
If using an oral thermometer in the mouth and want to compare it to the way Broda Barnes did the underarm, leave in your mouth for five minutes, then subtract 1/2 degree from your result to make it closer to underarm temp taking — the latter which is usually lower.
There is a problem. Right there. You have been taking away 0.5 C. But Janie has just referred to a temperature range of 97.8 – 98.2. Which makes it read as if she is referring to Fahrenheit. Half a degree Fahrenheit is 0.2777778 Celsius. At least, that is how I read it! But as she does not actually say so, I could be incorrect.
Also, see the picture which shows how temperature typically varies within the mouth.
Diagram of mouth showing how temperature varies by precise location.
Interesting diagram about the mouth temperature. I have a theory to explain why the under arm temperature is more useful for this purpose than either the mouth or the ear. It's only my own idea so please feel free to ignore.
If you look at the diagram the hot spot corresponds to the location of fairly large blood vessels in the tongue, which will envelope the thermometer. As a result I think the mouth thermometers are really measuring blood temperature rather than body temperature, and the same is probably true for the ear.
Why should blood and body temp be different ? Well an important function of the blood is the transfer of heat around the body, keeping the hot core cool and warming the cool periphery. Heat transfer is physically impossible unless the blood is at a different temperature to the body.
Blood temp measurement is ideal for fevers, but we are interested in how well the mass of core cells are functioning and the measure of this is how much heat the core body is generating. The closest we can get to this is the underarm area. ok there is also rectal but lets not go there.
Yes – blood carries heat. The main arteries tend to be warmer. The main veins tend to be cooler – especially if the flow is returning from having been down legs or arms. (There is sometimes a level of counter-current heat exchange.)
The heat pockets of the mouth are obviously very strongly influenced by the blood flow.
But we have to ask how does the blood get warmed up again? Let us imagine standard blood temperature being 37.0. It goes round your body and returns having lost a degree – so now 36.0. How does it get heated up to 37.0 again? Your blood doesn’t “burn” fuel. Your tissues do. Some parts of you body must heat up above 37.0 in order to reheat the blood to 37.0.
I am not convinced that it is sensible to add or subtract an arbitrary number from your readings anyway! I think I would record as it reads without adjustment. And accept that there will be a difference from what you read and any other source which suggests a different place of measurement.
Roughly speaking, adjust the target rather than your reading.
I do not think adjusting you oral/ear measurement to give the equivalent of the arm temperature is a good approach. What not just measure the arm temperature in the first place.
Interesting post.I also find different thermometers (of the same type) can be wildly different. My off-the-shelf digital thermometer regularly measured around 35 degrees. I purchased a more accurate basal thermometer, and now consistently get around 36.8 degrees. I have measured my temperature with both in my mouth at the same time, and measures 0.7 degrees difference!
I am always wary of posts about low body temperature, after my own experiences.
I just bought one on Amazon - the fertility tracking ones are generally quite good, because they need to detect very subtle changes in temp (they give readings to 2 decimal places).
The original was from Lloyd's pharmacy, so i put too much trust in brand rep it seems...
My thermometer is a digital one with a heat coupler (by femometer) - it takes a while to get to temp, but seems to be pretty reasonable for the purposes of making sure I don't have a fever
Just to follow up on this post, I made some temperature measurements, using the Broda Barns technique and measuring the both the arm temp and the ear Ttmp at the same time. I was looking for a fixed difference between the two hoping to use the Ear measurement in future as it is a bit easier. Just over two weeks measurement every morning is given below. Sorry the range seems to have got knocked off the chart but its about 36.5 to 37.3. Its a bit random and there is no fixed adjustment to convert to the arm temperature. I have abandoned the ear measurement approach.
This is the temperature measurements using the Geratherm Classic thermometer under arm, using the Broda Barns technique. The reading were taken at exactly the same time as the Ear temp give above. There is a clear pattern here and I am much happier with the reading.
The peaking in temperature is according to Dr. Rind a clear indication of adrenal dysfunction, and this was confirmed by a cortisol test, which is twice the top of the range all day long. I am taking some urgent action to reduce cortisol, and to try flatten the graph. Too earlty to tell if it will work by by sleeping has improved.
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