At-Home Thyroid Testing Kits: What We Know...and What We Don’t. An Interview with Dr. Hyesoo Lowe
The COVID-19 pandemic has completely uprooted lifestyles across the globe. People are working, socializing, and even visiting their doctors from home.
As people become more and more comfortable with the idea of receiving their health care remotely, several companies have begun selling at-home thyroid-testing kits. A simple Google search will reveal several vendors. Now that the indefinite future creates extra burden and anxiety when it comes to venturing outside, are these self-testing kits worth considering?
Endocrinologist and thyroid expert Hyesoo Lowe, MD, answered some questions to help clarify some pros and cons.
What is your view on at-home thyroid testing kits?
It depends on what you are looking for. As a screening test, home testing may be helpful for people to have a quick and convenient way to obtain a test result that can guide a referral to appropriate physicians.
Home testing kits for various laboratory parameters are part of a technology that is rapidly developing. We're currently comfortable with these tests in the domain of home pregnancy tests and fingerstick glucose testing.
In endocrinology, there are some hormone assays that are measurable with salivary testing, and a variety of other lab tests are being developed for analysis on saliva, finger prick blood samples, and even hair samples.
As patients are increasingly becoming more active in their own healthcare, the market for home lab testing could really change how medical care is accessed as this information is obtained.
Do you have a specific opinion? Are you skeptical? Optimistic? Concerned?
I’m cautiously optimistic.
Do you see advantages? Positive impacts?
For sure, home testing is convenient for patients. Turnaround time for patients receiving lab results would be faster since they're delivered directly to the patient.
Do you see risks? Drawbacks? Something lost when the test is not conducted in a medical facility? Any dangers?
In medicine, laboratory testing is generally used by a physician to evaluate a patient's symptoms and clinical findings to guide medical decision-making.
The decision regarding which tests are needed lies with the physician who is trained to evaluate the patient's condition, who then orders appropriate lab tests after a thorough assessment has been made. Thus the doctor has taken into account a number of factors including the patient's symptoms, history, family and environmental background, medications, and other factors that would guide the proper choice of testing.
The danger of in-home testing is that the lab testing would have occurred prior to a medical evaluation, since the patient has already done their own lab tests. This may be helpful to a patient who is curious about a particular condition such as thyroid, or cholesterol, for example. However the caveat is that the patient may not be choosing the correct lab tests, and actually may require a different panel of tests to fully evaluate their condition. Again, interpreting lab results is very important, so abnormal values on home tests should trigger a full evaluation with a physician.
Also, no lab test is 100% accurate, so the possibility of false positive or false negative results introduces a degree of error requiring appropriate interpretation. This is also the reason that we don't have a broad testing panel which "checks everything." Additionally, quality control is an issue, as the home testing kits for thyroid are not standardized. Currently, there is insufficient data from large studies to confirm how well home tests correlate with serum values.
The kits apparently test for TSH, T3, and T4, as well as thyroid peroxidase antibodies. Which thyroid hormones are the important levels to understand? Is it important to test 3 kinds? Why? What about thyroid peroxidase antibodies
The most important thyroid blood test for initial evaluation is the TSH [Thyroid-stimulating hormone]. If the TSH level is normal, it is highly unlikely that the patient has active thyroid disease.
Thyroid antibodies and other hormone tests can be helpful in evaluating thyroid conditions, for sure. However it is not always useful to test these on an initial self-testing panel, because interpreting these results can be tricky, and would require further discussion with a thyroid specialist, who is very likely to repeat this testing with a blood draw.
One vendor states that testing all these levels is a good baseline practice, and even to continue over time — it actually compares this to getting a car checked out.
That aside, how regularly should people test their thyroid levels?
Checking thyroid labs can be useful in the evaluation of a symptomatic patient. However, it is not recommended to routinely check thyroid labs in an asymptomatic person.
One vendor lists a huge number of “related symptoms” (perhaps suggesting that some combination of these symptoms would merit purchasing an at-home test kit). The related symptoms include sluggishness, bloating, high cholesterol, shaking, heat sensitivity, thinning hair, etc.
Are there particular symptoms or combinations of symptoms that you look out for as a red flag?
The main challenge with identifying thyroid symptoms is that the symptoms caused by thyroid disease are quite nonspecific. For example, many people with thyroid disease report fatigue and weight gain, however many people with these same symptoms do not necessarily have thyroid disease and need other evaluation or treatment.
This test requires a pin prick blood sample, dropped onto a piece of paper, and sent through the mail. More complicated than a pregnancy test, for example, but likely it is still manageable.
If a patient came to see you with results from an at-home kit, would you trust it or repeat testing?
There is variability as to how a patient collects their specimen, so this quality control will have to be worked out. Also the accuracy and precision of home testing kits is currently not validated in large studies. So if a patient came to me with an abnormal result on a home test, I would certainly repeat the test with a blood draw and send it to a lab which uses large analyzers with verified accuracy and less room for error.
The bottom line is, just as I could search the internet and run some diagnostics on my car, this can only take me so far in addressing my car problem. There is no substitute to bringing it in to a licensed mechanic for a professional assessment.
In general, do you think that more people should have their thyroid hormone levels tested? Or should people only test if they experience symptoms?
Generally speaking, asymptomatic patients do not need to be testing thyroid blood tests. There are exceptions in the case of pregnancy concerns, or certain medications which interact with the thyroid, but these should definitely be addressed with a doctor instead of self-testing.
Can you think of anyone who might benefit from these tests being done at their own home?
Home kits for thyroid testing may be a convenient and accessible first step in patient-driven evaluation of symptoms. Having said that, a thorough history and examination by a board-certified physician is always recommended. So I see these home tests more as a potential screening tool for thyroid disease, which would then lead to a specialist referral if the test is abnormal. Or, if a patient has normal results but continued symptoms, this should trigger a medical evaluation to see what other testing is necessary to pursue.
If home testing is developed to be well validated and accurate, I could also see home testing being potentially useful to monitor thyroid hormone levels in patients on thyroid medication. However this would require very high accuracy, since very small changes in hormone levels would need to be detected, and adjustments in medications need to be done very carefully to ensure correct dosing.