Most doctors, including endocrinologists, rely on a standard thyroid test, TSH, to screen for thyroid problems. This test measures Thyroid Stimulating Hormone (TSH), a pituitary hormone whose function is to stimulate thyroid hormone production by the thyroid gland. When thyroid hormone production goes down, TSH goes up. There is a range of TSH levels that is considered normal. For most doctors, TSH is the only diagnostic test for hypothyroidism that they use and the most sensitive marker of peripheral tissue availability of thyroid hormone. If TSH is within a normal range, most doctors will “rule out” thyroid problems as a cause of symptoms.
However, there’s a problem with practicing medicine this way. It is becoming more and more obvious that the TSH test simply does not detect all thyroid hormone problems. It does not detect any problems you may have converting T4 (the inactive form of thyroid hormone) to T3 (the active form). TSH also cannot detect thyroid hormone resistance, which happens when cells are unable to allow thyroid hormone inside because their receptor sites are malfunctioning. Both of these thyroid hormone problems are more common than most doctors realize, and they are seldom detected. The TSH test also does a lousy job of determining a correct dosage of thyroid replacement hormone.
You can think of it this way: Your body is built according to what is written in your DNA. The whole purpose of your thyroid system is to determine how FAST your DNA is transcribed, or in other words, to determine how fast you live. How fast you live is best measured by taking your temperature. A thermometer is literally a speedometer. It measures how fast the molecules in your body are moving. When you are driving down the street and you want to know how fast you’re going you don’t look at the gas gauge, you look at the speedometer. In a similar way, if you want to know how fast you’re living, look at your thermometer, not your blood tests. The blood tests may only help you explain why your temperature is low, just like the gas gauge in your car showing empty could explain why your speedometer reads zero. If your body temperature is consistently low–below 98.5 F, or 36.94 C, but typically lower than 97.8 F, or 36.56 C.–there is a good chance you are “living slow,” which could explain a lot of your symptoms. Fortunately, it is usually possible to restore low body temperatures to normal so you can live well again (for example. with the prescription of T3, the active form of thyroid hormone). (For detailed instructions for how to take your body temperature correctly, see “How are body temperatures measured?” on my website.) Blood tests, such as TSH, free T4, free T3, reverse T3 and thyroid anti-bodies can help determine a course of action and help with prognosis.
Your doctor can call us at 800.420.5801 to get more information about how to use T3, along with nutritional and herbal support for thyroid problems, and to discuss your individual case. You can also use our website to find the health care practitioner closest to you who is trained in T3 treatment.
Fraser WD, Biggart EM, OReilly DJ, et al. Are biochemical tests of thyroid function of any value in monitoring patients receiving thyroxine replacement? Br Med J (Clin Res Ed). 1986 Sep 27;293(6550):808-10.
Koulouri O, Auldin MA, Agarwal R, et al. Diagnosis and treatment of hypothyroid-ism in TSH deficiency compared to primary thyroid disease: pituitary patients are at risk of under-replacement with levothyroxine. Clin Endocrinol (Oxf). 2011 Jun;74(6):744-9.