Thyroid UK




There is one simple thing almost anyone can do at home to uncover an underactive thyroid:

Take your own temperature.

The "basal body temperature" test was developed by Broda O. Barnes, M.D.,

Because thyroid hormone is so vital to cellular metabolism, reduced thyroid function often manifests as a drop in body temperature to below the normal level of 98.6*F. Barnes recommended the following procedure:

Immediately upon awakening, and with as little movement as possible, place the thermometer under the tongue or in the rectum.

Leave it there for 10 minutes.

Record the readings on three consecutive days

If the average temperature over the three days is less than 97.8*F, then, according to Barnes, you may have hypothyroidism. Even if you have had a blood test and were told your did not have a low thyroid reading, you might go back and look at the test results again. You may find that your blood levels of thyroid hormones are actually low normal. Many people who are within the so-called "normal" range but below the midpoint could benefit enormously from thyroid supplementation.

Your optimum oral temperature should be 98.0 in the morning before arising. Your oral temperature should rise to 98.6 to 99 degrees for about 10 hours a day (from 8 am until 11 am).

A good test time is to take your oral temperature between 11 am and 3 pm. The next time to do this is 20 minutes after lunch which is when your thyroid function should be at its best.

It is so important to work on getting and keeping your temperature at 98.6. The thyroid system is a vicious circle, one thing leads to another until bacteria, parasites, and viruses attack and cause other diseases and symptoms, including the body's wanting to attack itself. When body enzymes are not the correct temperature, 98.6, they don't turn into correct hormones, which then cause illness.

Even if your temperature is normal and you still have symptoms, you may have a low grade infection that is raising your temperature. Symptoms are a really important factor that need to be taken into account. Once the low grade infection is taken care of, you will be able to pick up a low temperature.

size of a Dollar is 26mm

Purchase an inexpensive bottle of the brownish-red iodine in the drugstore. Paint a circle about the size of a silver dollar on your stomach, If this color is absorbed in two to six hours there could be an iodine deficiency. And since this nutrient is necessary for the body's production of tyrosine.

12 Replies

Hi trw99, I found your post very interesting. I have been taking my sons temperature for appx a month now, he very rarely reaches 98 f and more ofter sits at 95f, we have had one peak to 99f in a month. I was told about the Iodine by a family member and did this only I was told to put it where you would get a bunyon. As a point of comparison I did my sons and mine. Mine was there untill the morning after and my sons was gone in an hour. I told my GP about this and he said"old wives tale" He has said( Friday) he may have a thyroid problem but at his levels it is extremely unusual to have any symptoms and he thinks there may be an underlying cause which is why he is reluctant to treat.


I think you may be spot on, Before I was diagnosed with a thyroid problem I used to burn up through the night, I always suspected I had some kind of infection, my partner used to say I was so hot she could come nowhere near me. I never went to the doctor because I just thought it was normal for me, when I did go just for a routine well man check up it was found I had a problem with my thyroid, I am now on 125mg of thyroxine.


I found this very interesting. I'm off to Boots today to buy a thermometer - not sure they will have iodine though.


Apparently for menstruating women, you need to get the basal level on days 2/3/4 of period. Mine were definitely lowest on those days, but are generally lower throughout the month.

Anyhow, I presented my low temperatures, clinical history (only one third of thyroid left, rest surgically removed, and this has a goitre) and 20 years of deteriorating blood tests moving from midrange to just within the 'normal range' and was told that this meant nothing. Needless to say, she wants to assign this to menopause and infection - neither of which are the case.

Will try the iodine test! But best hope seems to be to try another doctor.


I wish the iodine patch test were useful but, in my opinion, it is not.

There are several reasons for this:

1 Most of the iodine simply evaporates.

2 Some of the iodine might react to produce a colourless compound.

3 Only a tiny proportion of the applied iodine will ever be absorbed. And that proportion would not be enough to make the colour to disappear.

Further, in the UK much of the iodine in little bottles is actually povidone-iodine (e.g. branded Betadine) which would behave differently to tincture of iodine (iodine dissolved in ethanol).

If you wish to look further, may I suggest a couple of links? First to an interview by Mary Shomon (a well-respected US thyroid campaigner). Second to the web site of a doctor who is generally positive about iodine.

Topic: Disappearing Iodine Test

Interview of Dr David Derry by Mary Shomon

"The "test" of putting iodine on the skin to watch how fast it disappears is not an indicator of anything. "

"The bioavailability of iodine applied to the skin"

Guy E. Abraham, M.D

All the best



Yes I took my basal temperature for two weeks and it varied from 95 on waking to 97.5 at lunch time and the doctor was most happy to see this with the rest of my symptoms. However, I have been so lucky with my GP as he was the one who said I was borderline after routine yearly blood tests but he waited until I presented with symptoms. Thought my symptoms were just the aging process. Finding it amazing that i am now warm all the time and do not sleep in the afternoons and all this with 25mg a day. First blood test after 6 weeks my TSH is now at 2.9. Doctor would like it at 1.5 so another blood test in November. Have not had dosage increased at the moment as I feel so much better


iron deficiency can also cause low body temp i have this problem


I had a problem gettingbthe right sort of thermometer...cos I wanted an old fashioned mercury and glass and you cannot buy them in chemists anywhere.....I was told they were no longer available. On the theory that they are use up the rear end of animals ton take temp, I approached my Vet, well my rabbits' Vet and had one for £2.50 in 24 hrs...I thought that was a good flash of lateral thinking in an otherwise dumbed down brain...and yes mine was low too. But note you must not drink alcohol the night before...must push your core temp in your liver?!?


Follow this link to Thyroid UK's updated information on the Basal Temperature Test


my temp has risen slightly since being fully medicated but it is still low so maybe I have a naturally low temperature anyway??


The issue is that the basal test isn't infallible, and should only be used as part of diagnosis.


The issue is that the basal test isn't infallible, and should only be used as part of diagnosis.


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