Basal Temperature Test – Check Thyroid Activity

by | Aug 14, 2003 | Self-Help

There is considerable evidence showing that the current blood tests for the diagnosis of mild, subclinical hypothyroidism are insensitive and somewhat lacking in accuracy. Broda Barnes, MD, an Endocrinologist and thyroid specialist, in his book, Hypothyroidism, an Unsuspected Illness, explains his opinions and theories about this matter. He proposes that the most sensitive and accurate test for picking up low thyroid function is simply to check the axillary (armpit) basal (baseline upon awakening) temperature.


Use an oral thermometer, which is made ready to use the night before and put within easy reach on the bedside. DO NOT using a mercury thermometer to eliminate the possibility of accidental breakage and the potential mercury toxicity. If you use a mercury thermometer, take all measures to prevent breakage.

Put the thermometer in your armpit for five minutes. Do this before you’ve gotten out of bed, had coffee, food, done anything significantly physical. Dr. Barnes suggests using the axillary (armpit) temperature, rather than the mouth, because so many people have low grade unsuspected sinus infections. These infections generate heat only in the oral cavity thereby falsely raising the oral temperature. If you do not have infections, you may take your oral temperature. For young children or the disabled, you may use the rectal temperature. Record your temperature each morning for five days.

For women, additional consideration is needed during ovulation, since ovulation somewhat elevates your temperature. Because of this, women who menstruate should start recording your temperature on the second or third day of menstruation.

Normal axillary (armpit) or oral temperature is in the range of 97.8 – 98.2 F. Normal rectal temperature is 98.8 ‑ 99.2 F. This data of your daily basal temperatures will assist in assessing your cellular thyroid hormone activity. Dr. Barnes estimates that greater than 40% of the adult population has hypothyroidism which can be associated with hypoglycemia, allergies, psoriasis, acne, undiagnosed skin problems, hypertension, obesity, depression, and many other ailments. See our website for additional information on Integrative Medicine.

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