Hypothyroidism - Basal Temperature Test

Blood tests for thyroid function only measure the thyroid hormone in the blood, which may have no relation to the amount of hormone that actually gets into the cells which need it.  Blood tests can show adequate levels of T-4 hormone but the person has all the signs of low thyroid function, because not enough T-3 hormone is getting to the tissues. As a result, most cases of hypothyroidism (low functioning thyroid) go undetected. 

There is a simple and reliable test you can do at home to test if your thyroid gland if functioning optimally or not.  It’s called the basal temperature test (BTT). The BTT measures the result of one critical thyroid activity, the maintenance of body temperature. 

The ideal temperature at which all bodily biochemical reactions function most efficiently is 37 C (98.6 F).  When temperatures are below or above this norm, chemical messengers become mis-shapen and no longer precisely fit into the receptor sites they are intended to activate. A shift in temperature of only a fraction of a degree can have a significant effect on the degree of “fit” between enzyme and substrate, neurotransmitter and receptor, hormone and target cell, antibody and foreign protein. 

The BTT requires taking underarm (axillary) temperature first thing in the morning before rising, when the entire body is at complete rest.  Men, prepubescent and post-menopausal women can take this test any time. 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 begins.

To do the BTT, place a liquid-type clinical thermometer, well-shaken down, by your bedside. Upon awakening and before stirring from bed, place the bulb of the thermometer under your arm and hold it there for 10 minutes. Record the reading for two consecutive days. A range from 36.6 C (97.8 F) to 36.8 C (98.2 F) suggests normal thyroid function.  Temperatures below 36.6 C (97.8 F) indicate low thyroid function (hypothyroidism). Those above 36.8 C (98.2 F) indicate an overactive thyroid gland (hyperthyroidism).

If a person has both a low BTT reading and symptoms of low thyroid function, then hypothyroidism is almost certain.

Nutrients that support thyroid function include iodine, selenium, cysteine and the B-complex vitamins.


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