BBT - Basal Body Temperature Test

Home Thyroid Test: Basal Body Temperature

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The basal temperature test (BTT) is an effective self-test for measuring thyroid function. It is far more reliable than any thyroid blood test. That is because the BTT measures the actual result of one critical thyroid activity, namely the maintenance of body temperature. Blood tests measure only the amount of thyroid hormone circulating in the bloodstream, which may or may not be typical of how much active hormone (T3) actually gets to the individual cells that need it. Body temperature is directly related to thyroid activity. 370C (98.60 F) is the ideal temperature at which all of the body's biochemical reactions function most efficiently.

In the absence of starvation and acute fever (which affect body temperature), the BTT is the most effective single measurement we have for finding thyroid dysfunction. If used alone, it can be over 85 per cent reliable. If combined with symptom surveys, however, reliability approaches 100 per cent.

Important To Note Before Taking Test:

  • Take underarm temperature first thing in the morning before arising, when the entire body is at complete rest. Under the tongue readings are inaccurate.

  • To eliminate the temperature fluctuations that accompany one's cycle, menstruating women need to do the BTT on the second and third mornings after their flow starts.

  • Use a liquid-type clinical thermometer. Shake well before taking test.

  • Place thermometer beside the best before going to sleep to take a reading as soon as

    you rise.

    How to Perform the BBT Test:

    1. Upon awakening and before stirring from bed, place the bulb of the thermometer under the armpit and hold it there for 10 minutes.

    2. Record the reading on two consecutive days.


    36.60C (97.80 F) - 36.80C (98.20 F) NORMAL THYROID FUNCTION



    Based on David W. Rowland, PhD “Assessing Biochemical Individuality'