Question:
My doctor is using my Basal Body temperature as a guide to determine if I've met my optimum thyroid medication level.
I take my temperature under my arm first thing upon waking for 3 days in a row and write it down. I have read recently that this is much more accurate than the blood tests (target range being 97.8 to 98.2), so why don't other doctors use this method? I had never heard of using the basal temperature until I went to this doctor. As a side note to you, my basal temperature for the 3 days ranged from 95.8 to 96.8, though my TSH level at my last doctor was in the normal range (that doctor has been "fired" by me). Since that TSH test, my thyroid meds have been increased by my new doctor, and my BBT is still low.
I would like to hear another doctor's opinion on the BBT method of testing...
Drs. Richard and Karilee Shames Answer:
There is considerable evidence that current tests both for the diagnosis of hypothyroidism and for the management of a case under treatment are tests that lack sensitivity and accuracy. Faced with this situation, in my medical practice and in my second opinion telephone coaching sessions with patients of other practitioners, I absolutely insist on basal temperatures being part of the equation.
For people who are wondering if their health problems are due totally or in part to an underactive thyroid, basal temperature testing is not the only diagnostic maneuver that I use, but it is one additional piece of data along with symptoms, family history, related conditions, and signs of abnormality upon physical examination. For those who have already been diagnosed with hypothyroidism, the basal temperature test is an additional piece of observational measurement that helps determine whether a person is on the right medicine and/ or the right dose, along with considering the response to medication, physical signs, especially ankle reflexes and skin temperature, and blood test results.
In other words, the doctor who is suggesting that you use the thermometer testing maneuver you described in your question is doing what I would consider a very proper medical maneuver if indeed that doctor is also considering the other factors I have mentioned. Your information saying that basal temperature testing is "much more accurate than the blood tests" should be taken with a grain of salt. Like many things, the statement is true for some people, but not true for everyone.
Therefore, a prudent practitioner and a prudent consumer, will use as many different clues and pieces of information as possible to help make the sometimes difficult decision about whether or not to treat a health problem as a low thyroid issue or, if already being treated, whether or not to add or change medication or supplements.
Here is a good example: I generally find out on the first conversation with a potential thyroid sufferer what is their present percent of total optimal function that they currently enjoy. Some people say to me, "Dr. Shames, I'm glad I can talk to you on the phone from across the country because I'm only feeling 20% of my prior self, but my doctor says my TSH test is normal, so they are not going to do anything further."
This is a person who should be following their basal temperature, rather than their TSH. Most likely their basal temperature will still be low, suggesting a need for further medicine, and I endorse people going along with that suggestion regardless of TSH levels.
You asked why other doctors don't use this method. I believe it's because many of them have not read the 1970s book, Hypothyroidism: The Unsuspected Illness, by Broda Barnes MD. In this compelling volume, Dr. Barnes, the granddaddy of the thyroid field, put his many decades of experience into a succinct and easily-digestible form. It was here that the basal temperature test was first explained in proper detail, with the proper rationale and research. From your question, it is clear to me that you did not proceed along the exact lines that Dr. Barnes would have most recommended.
He recommended that you do the morning temperature sampling for ten days in a row, not just for three. Menstruating women should start this ten-day period on the third day of their cycle. It is best to use a basal thermometer, which is more accurate than a regular oral thermometer. Currently, most folks are able to locate non-mercury thermometers, which we recommend as more friendly to the environment. This kind of basal thermometer is actually more accurate for this purpose than any digital electronic thermometer. Dr. Barnes also suggests that the thermometer not be used orally, but instead used under the arm, with the person lying quietly in bed, and the arm comfortably at the side. The temperature is taken upon awakening, before rising up out of bed for any reason.
Dr. Barnes felt that this test was a check on the most basic function of the thyroid gland: its ability to regulate the metabolic furnace of the body and to control the temperature. An average of ten days is a very useful indication, therefore, of one's overall thyroid status, and in many people, it may well be more accurate than the blood tests. Temperature testing, however, is not infallible, and - like any other test - should never be used alone to rule in or rule out a thyroid condition, or to dictate therapy. This is simply a good piece of information that should be used wisely. I use it with every one of my patients who will do the test, and I recommend to other practitioners to do the same. It would be a welcome addition to many doctor's thyroid management regimen.
