Measuring basal body temperature

Your body temperature reflects your metabolic rate, which is largely determined by hormones secreted by the thyroid gland and by the ability of your cells to convert these hormones to their more active form. Your level of thyroid activity can be determined simply by measuring your basal body temperature. All that is needed is a high-quality thermometer.


  1. Place the thermometer by your bed before going to sleep at nights. If using a mercury Thermometer, shake it down to below 95 degrees F.
  2. On waking, place the thermometer in your armpit for a full 10 minutes. It is Important to make as little movement as possible. Lying and resting with your eyes Closed is best. Do not get up until the 10 minute test is completed.
  3. After 10 minutes, read and record the temperature and date. (A convenient form is Printed at the end of this appendix: Fig. A7.1.)
  4. Record the temperature for at least three mornings (preferably at the same time of the Day) and give the information to your physician. Menstruating women must perform the test on the second, third, and fourth days of menstruation. Men and post- menopausal women can perform the test at any time.
Name _____________________- MonthDate      Temp       Date      Temp       Date      Temp       Date      TempDate      Temp       Date      Temp       Date      Temp       Date      TempDate      Temp       Date      Temp       Date      Temp       Date      Temp


Your basal body temperature should be between 97.6 degrees and 98.2 degrees F. Low basal body temperatures are quite common and may reflect hypothyroidism.

Common signs and symptoms of hypothyroidism are:

  • Depression
  • Difficulty in losing weight
  • Dry skin
  • Headaches
  • Lethargy or fatigue
  • Menstrual problems
  • Recurrent infections
  • Sensitivity to cold
  • Menstrual problems

High basal body temperatures (above 98.6 F) are less common, but may be evidence of hyperthyroidism. Common signs and symptoms of hyperthyroidism include:

  • bulging eyeballs
  • fast pulse
  • hyperactivity, nervousness
  • inability to gain weight
  • insomnia, irritability