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.