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Why TSH Testing is Not Enough and Why you Should Check your Body Temperature

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.

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  1. Carmen February 28, 2015 at 9:17 pm - Reply

    Can I buy T3 myself since my doctors don’t pay much attention about my extreme cold hands, falling hair, dry skin, weak nails that break and are soft.

    • Dr. Denis Wilson March 1, 2015 at 5:38 am - Reply

      Hi Carmen, T3 is a prescription medicine. Best regards.

  2. Bryll April 4, 2015 at 9:43 pm - Reply

    What is the difference between WTS and HASHIMOTO’s? I have symptoms that apply to both….

    • Dr. Denis Wilson April 5, 2015 at 5:16 am - Reply

      People with Hashimoto’s (autoimmune attack on the thyroid gland that causes hypothyroidism) can have WTS (impaired T4 to T3 conversion and utilization in the cells) at the same time.

  3. Cheryl June 5, 2015 at 8:46 am - Reply

    Dr. Wilson I have been looking at your website for over a year now and have not committed to ordering the Thyrocare yet. My health issue has not changed. My TSH is still elevated but my T3 and T4 counts are normal. Yet, I’m still suffering with foggy memory, anxiety, pressure in my throat area, flushing, weaknesses, blood pressure, indigestion, constipation, acne, insomnia, allergies, you name it I seem to have it. Then all of a sudden I go through this time when I am perfectly fine but I know when it starts back it comes on suddenly without warning, I begin to break out in a hot flash and my mind get foggy and my eyes get blurry. I’m on AmLodipine Besylate 5mg but that’s not helping. You talking about stress…I think I’m going to take the risk and order the Thyrocare I just wanted to know if that is the supplement I should start with? Thank you

    P.S. I do have low body temperature also…I saw my Dr about it and she took another Thyroid test and said my thyroid was normal but my again my TSH was up and I’m full menopausal but she never prescribed anything for it.

    • Dr. Denis Wilson June 7, 2015 at 8:25 am - Reply

      Hi Cheryl, I can’t give specific medical advice over the internet but I do know that normalizing a low temperature can have a big effect on how people feel.

  4. Melissa November 7, 2015 at 5:29 am - Reply

    Dr. Wilson,
    I’ve been struggling with hypothyroid symptoms for 3 years now. I’ve seen several doctors who have run tests and all levels of TSH have come back normal. I requested they run T3 and T4 tests. Many refused. I did find a doctor here recently who ran free T4 and Total T3. In reading, you’ve mentioned the importance of free and reverse T3, as well as antibodies testing in another article. I mentioned this to my current endo, they expressed that free T3 was (and I quote) the most unreliable test there is. And even if these test come back elevated they wouldn’t treat me because the other tests (TSH, TT3 and FT4) came back indicating thyroid function was normal. Based on readings, my T3 hasn’t been measured (as TT3 is just another measure of T4). Could I still have a thyroid issue which is causing lack of concentration, fatigue, dry skin, weight gain and low temperatures (95.7 – 96.8 averaged over a month of measuring)? Should I have these additional tests run? And if they are elevated are you aware of any doctors in the Houston TX area who are more forward thinking? Also, I have read that the ranges of these tests are controversial. Do you have a range for FT4, TSH and TT3 that you consider optimal? For example, falling with in the top half or quarter of the range? Thank you in advance for any input.

    • Dr. Denis Wilson November 9, 2015 at 8:29 am - Reply

      Hi Melissa :) Your low body temperatures prove that your metabolic rate is low. Your normal TSH proves that it’s not because of your thyroid gland thyroid hormone production. That means the problem is further downstream, in the cells of your body. There is no blood test that can prove that because blood tests measure what’s in the blood, not the cells. You can check here for a doctor in your area:

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