Self-directed thyroid management

Is there an at-home test you can do to gauge thyroid status?

Yes. Measure your temperature.

Unlike a snake or alligator that relies on the sun or its surroundings to regulate body temperature, you and I can internally regulate temperature. The hypothalamus-pituitary-thyroid glands are the organs involved in thermoregulation, body temperature regulation. While the system can break down anywhere in the sequence, as well as in other organs (e.g., adrenal), the thyroid is the weak link in the chain.

Thus, temperature assessment can serve as a useful gauge of thyroid adequacy. Unfortunately, temperature measurement as a reflection of thyroid function has not been well explored in clinical studies. It has also been subject to a good deal of unscientific discussions.

How should temperature be measured? The temperature you really desire is between 3 am and 6 am, while still asleep. However, this is difficult to do, since it would require your bed partner to surreptitiously insert a thermometer into some body orifice without disturbing you. A practical solution is to measure temperature first upon arising in the morning, before drinking water, coffee, making the bed, etc.--immediately.

While traditionalists (followers of Dr. Broda Barnes, who first suggested that temperature reflects thyroid function) still advocate axillary (armpit) temperatures, in 2009 it is clear that axillary temperatures are unreliable. Axillary temperatures are inconsistent, vary substantially with the clothing you wear, vary from right to left armpit, ambient temperature, sweat or lack of sweat, and other factors. It also can commonly be 2-3 degrees Fahrenheit below internal ("core") temperature and does not track with internal temperatures through the circadian rhythms of the day (high temperature early evening, lowest temperature 3-6 am).

Rectal, urine, esophageal, tympanic membrane (ear), and forehead are other means to measure body temperature, but are either inconvenient (rectal) or require correction factors to track internal temperature (e.g., forehead and ear). For these reasons, we use oral temperatures. Oral temperatures (on either side of the underside of the tongue) are convenient, track reasonably well with internal temperatures, and are familiar to most people.

Though there are scant data on the distribution of oral temperatures correlated to thyroid function, we find that the often-suggested cutoff of 97.6 degrees Fahrenheit, or 36.4 C, seems to track well with symptoms and thyroid laboratory evaluation (TSH, free T3, and free T4). In other words, oral temp <97.6 F correlates well with symptoms of fatigue, cold hands and feet, mental fogginess, along with high LDL cholesterol, all corrected or improved with thyroid replacement and return of temperature to 97.6 F.

But be careful: There are many factors that can influence oral temperature, including clothing, season, level of fitness, "morningness" (morning people) vs. "nightness" (night owls), relation to menstrual cycle, concurrent medical conditions.

Also, be sure that your thermometer can detect low temperatures. Just because it shows low temperatures of, say 94.0 degrees F, doesn't mean that it can really measure that low. If in doubt, dip your thermometer in cold water for one minute. If an improbable temperature is registered, say, 97.0 F, then you know that your device is incapable of detecting low temps.

A full in-depth Special Report on thermoregulation will be coming soon on the Track Your Plaque website.

Comments (9) -

  • Dan

    4/2/2009 6:11:00 PM |

    Dr. Davis.

    What do you think of brachial artery reactivity testing (BART).  There's another study (here: linking high-fat diets to decreases in flow-mediated vasodilation.  I was wondering your thoughts on the likelihood that BART is measuring a significant risk factor for CVD.  

    This is definitely off-topic so apologies.

  • Anna

    4/2/2009 6:14:00 PM |

    As you say, most common thermometers are calibrated to measure fever or elevated temps.

    Look for basal thermometers, often sold for detecting ovulation, so they'll be with fertility and
    "women's products" aisles, but may be used by anyone. Basal thermometers are calibrated low enough to detect the low temperatures of hypothyroidism.

    When I was experiencing infertility 15 years ago, I handed over many months of early morning temperature charts to the specialists, with all my menstrual cycle details.  Routinely, I had temperatures in the 96°F range, unless I was sick or ovulating (98.6F was a fever for me back then).  A spike to 97 indicated ovulation.  No one ever questioned the low temps in terms of my lack of fertility, of course, but the nurses joked about how cold I was.  If I only knew then...

  • Anonymous

    4/2/2009 8:08:00 PM |


    This is very informative.
    What is the best base level of Iodine daily to promote thyroid health?

    Thanks for you great blog!


  • Anonymous

    4/4/2009 4:33:00 AM |

    Using a thermometer to determine thyroid function may be worthwhile, but realistically... how useful is it really?

    By this I mean, say it registers low. Okay, so now you go to your doctor and try to get your thyroid levels measured. A GOOD doctor who knows what they doing (which is rare) will measure Free T3, Free T4, TSH and antibodies.

    Unless your TSH is in the >3 range, along with raised antibodies, the chances of getting treatment is close to nil, regardless of your temperature. And usually most doctors look for TSH >5.

    Perhaps you can find the rare doctor who will treat based on antibodies alone, or the doctor who will consider a TSH >2.5 significant, but prepare to see a lot of doctors in order to find one who will treat.

    And recommending iodine without checking antibodies first, probably is a bad idea. Iodine + Hashimoto's doesn't always work out so well.

  • Monica

    4/8/2009 3:12:00 AM |

    Thanks so much for this information.  I measured waking temps for around 6 months for fertility reasons.  Usually I was in the low to mid 97 range.  Just measuring, evening, it's only 97.9 -- as measured with two different BBT thermometers.  I've lost about 15 pounds on a wheat-free, sugar-free diet, but I have about 20 lbs. more to lose and often wonder why I can't seem to shake the extra weight.  This post has encouraged me to get my thryoid checked.  my mom, grandma, and great-grandma all have/had hypothyroidism.

  • Anna

    4/8/2009 2:59:00 PM |

    Monica,  based on my experience and of others I know, it might take some persistence on your part.  Learn as much as you can about thyroid function and various approaches to treatment; Mary Shomon's website and book are a good start.  Good thyroid function is critical for optimum fertility, healthy pregnancies, and healthy babies; several years after we gave up on trying, when hypothyroid symptoms became so pronounced, I read at least 5 books with different angles; if I hadn't I would have given up much too soon and settled for the wrong care.  Check with a few doctors (even out of network and out-of-pocket if you can) if you are told you are fine despite your symptoms or only need synthetic T4; it's worth it (esp if low thoyroid function might be affecting your fertility - I learned too late it probably was at least part of my infertility problem all along).  I got nowhere fast with my PCP of 10 years and the next physician I saw in my network and only a fraction better.  Even once I found better care out of network, it took a lot of tinkering with treatment and dose to finally feel and function closer to normal in the third year of treatment.  Don't get discouraged.

    I know there's a fine line between doctor-shopping to neurotically get what you think you need vs. being a tenacious advocate for your health (I was constantly aware of this).  Despite the dismissal of concerns and frustration I often experienced early on,  I wouldn't accept the constant push to take other meds offered to manage the symptoms just because the doc or lab held to an outdated TSH threshold or couldn't/wouldn't figure it out.  

    Good luck to you.

  • EMR

    2/10/2010 6:37:34 PM |

    Temperature assessment should be a great way to detect the disease.Thanks for the informative article.

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    3/4/2010 6:41:18 AM |

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