A Skeptical Look at Thyroflex Testing

Stephen Barrett, M.D.
March 1, 2019

Thyroflex testing uses a spring-loaded reflex hammer connected to a computer to assess the functioning of the patient’s thyroid gland. Proponents claim that it is more accurate than standard blood tests that measure hormone levels. This article explains why I question its value.

Background History

The Thyroflex device is marketed by NiTek Medical, of Scottsdale, Arizona, which leases it to practitioners in many countries. The company’s Web site states:

It is estimated that 80% of the population has a thyroid disorder. Many are unaware that they have the condition, but suffer from the symptoms. For this reason, thyroid function screening is vital for everyone, as a primary health assessment. . . . The patented Thyroflex is a non-invasive state of the art system to test, diagnose, titrate, and manage thyroid conditions. It uses reflexes, Resting Metabolic Rate and symptoms to accurately determine thyroid function. . . . The Thyroflex Test has a 98.5% accuracy rate [1].

A NiTek “patient guide” published in 2017 states:

For our Specialist Doctors to make your thyroid work correctly, say it is underactive hypothyroid—we have to make sure the other hormones, which we term “The Core Hormones,” are functioning correctly also. These hormones include the stress hormones (Cortisol, GABA, Pregnenolone, DHEA, D3, B’s), the sleep hormones (Magnesium, Tryptophan, serotonin, and Melatonin), the cancer prevention—Iodine/Iodide and CoQ10 & ACTH [2].

The Thyroflex was invented by Konrad Kail (1949-2011) and Daryl V. Turner, Ph.D. Kail was a naturopath who co-founded the Southeast College of Naturopathic Medicine and served as president of the American Association of Naturopathic Physicians, chair of Arizona’s Naturopathic Board of Medical Examiners, and a member of the National Center for Complementary and Alternative Medicine’s advisory council [3]. The Thyroflex Asia Web site describes Turner’s background this way:

Dr. Turner is a Thyroid, Iodine, Adrenal and Hormone specialist. He invented, developed and clinically trialed the “THYROFLEX”, a thyroid test involving the reflex speed, Neurotransmitters, and RMR [resting metabolic rate] , that accurately identifies your thyroid’s performance and the amount of thyroid medication a patient requires, plus the supporting Bio medications for the treatment of hormone imbalances. He also discovered an effective treatment for Hashimoto’s Disease. . . .

Dr. Turner is the innovator, creator, inventor and owns the intellectual property rights and worldwide patents to the Thyroflex, Thyrodine, and many other new medical breakthroughs and worldwide patents along with the Trademarks. He is the founder and head of TARI—Thyroid and Adrenal Research Institute, having developed, formulated and owns the Bio Pharmaceuticals and Bio Nutriceuticals. The prescribed Medications are FDA compliant and manufactured under the FDA Compliancy system, GMP’ed and ISO’ed. The medical devices and medications underwent clinical trials on 2,200 people, over 3 years and are peer reviewed and published, FDA & CE approved. The Devices and Bio hormones are manufactured by Nitek. It maintains a server network to monitor the testing worldwide. Nitek does not sell its equipment, every system is owned by Nitek (the Thyroflex’s are leased with pay per use). Dr. Turner developed the “Core Hormone” System to support the thyroid and the Bio hormones for males and females. . . . . Dr. Turner is CME certified for continuing education credits. Nitek Medical operates in 22 counties, and incorporates the advanced SAM medical software diagnostic suite, and a worldwide on-line Patient consulting service, and Scripting service, which is married into a worldwide patient medication fulfillment service from our licensed pharmacy and the STEM Cell program. Dr. Turner has been featured on many TV shows, Radio shows, Social media, and his body of work is written about by many other doctors [4].

The TARI Web site has reported that Turner has a bachelor of science degree, an MBA, and a Ph.D. degree said to be “focused on stress management in the human body,” but it does not indicate what school(s) issued them [5]. An acquaintance told me that Turner received a Ph.D. in international business from the Thunderbird School of International Management in Glendale, Arizona.

The Thyroflex patent application was filed in 2005 by Kail and Turner and was approved in 2007. The document claims that “thyroid dysfunction affects more than 30% of the U.S. population.” [6] Kail and Turner co-founded NiTek International, Inc. in 2006. [Some proponent literature spells NiTek with a small “t” and there are also variations in the company name (e.g., NiTek Inc., Nitek Medical, and Nitek International). I don’t know whether the name variations are the result of renaming of the company or whether the operators have done business under several similar names at the same time or different times.]

The Thyroflex licensing agreement indicates that practitioners who use the the device pay a registration fee, a monthly fee, and a per-test fee and are expected to do a minimum of ten tests per month. Most practitioners charge patients $55, $60, or $65 per test.

The Thyrodine device—the full name of which is Thyrodine Iodide Quantitative Fluid Analyzer—was said to measure iodide concentrations in saliva, whole blood, and urine. In 2008, the TARI Web site stated that TARI had recently developed the Thyroflex and Thyrodine devices and planned to conduct clinical trials, seminars, and training programs [7]. Proponent Web sites describe the Thyrodine was FDA-approved, but the FDA device registration and approval databases do not list it and I don’t know whether it is still in use.

Kail and Turner also founded the For Need Foundation International, a nonprofit corporation that was launched in 2006 and dissolved in 2011.

How the Thyroflex Test Is Administered

The Thyroflex system includes a laptop computer with preloaded Thyroflex software, an ordinary reflex hammer, a spring-loaded reflex hammer, a sensor that is strapped to the wrist, and a symptom survey questionnaire. The spring-loaded hammer and the sensor device are both connected to the computer. When a tendon is struck, stretch receptors within it generate an impulse that causes the attached muscle to contract.

To take the test, the patient completes the questionnaire and the answers are entered into the computer. Then the operator uses the standard hammer to locate the brachioradialis tendon on the forearm. The spring-loaded reflex hammer is then cocked, placed on the skin over this tendon, and triggered by pushing a button. The sensing device detects how long it takes for the brachioradialis muscle to relax after it contracts. The software then combines that information with data from the questionnaire and possibly laboratory tests (a) to calculate numbers that are said to represent the performance of the thyroid gland and (b) to recommend “bioidentical hormones,” dietary supplements, herbal products, and/or homeopathic products to correct supposed imbalances [8].

The software associated with the device is called Software for Age Management (SAM). Nitek’s welcome video states that “SAM does your thinking for you” and explains how it takes, the test results, says what is wrong, makes recommendations,, helps to monitor the patient’s progress, and includes a practice management system that can set appointments and send follow-up emails.” [9]. The SAM licensing agreement calls for payment of monthly and per-use fees and thanks signers for “choosing to be one of our select SAM research group members.”

The NiTek Pharmacy stocks hormones and supplements said to have been formulated “specifically to target the hormone imbalances and assist with anti-aging.” The Thyroflex Asia Web site lists 37 products that can be prescribed by practitioners and shipped directly to patients. For practitioners who do not have a license to prescribe, NiTek has set up a “Consultation and Scripting Service” through which their patients can obtain prescriptions from a licensed provider. As described on the this site:

We have available a full patient consultation service for remote locations on the planet earth. We have a number of fully trained integrative hormone specialists, that are able to consult with a referral from your medical center. The consulting Doctor will review the medical notes, tests, and personal profile then will call the patient up at the time selected and booked by the patient, and visit with the patient face to face via the Internet, analyze the patient’s files, and interaction, then write a prescription, which is then fulfilled at the Nitek pharmacy and set direct to the patients. We currently have 1000’s of patients under treatment in 22 countries around the world [10].

Practitioners also have the option to buy products “wholesale” and resell them to patients. NiTek has illustrated the income potential by posting a spreadsheet showing how, from June 2015 to December 2016, “Dr. Bryant H” netted $446,899 from administering 1,915 tests and selling products at a nearly 100% markup.

Nitek’s Web site has posted additional information about the consultation and scripting service in a password-protected location I cannot access. But I did locate a Google-cached version of a document that describes the consultation process and contains a request form for use in Australia in 2008. The document states that Dr. Alan Hadley of Brisbane, Australia, would be available, that there had to be at least a phone consultation, and that:

The patient information, four modes of test results (TSS, reflex time, RMR, temps) and practitioner notes form the valuable basis from which the patient file can be established. Any past information and blood test results would also be appreciated, but are not essential. Subsequent scripts for the same patients will only require the test results from the Thyroflex and the practitioners recommendation unless additional medical information is requested by Dr Hadley for that patient’s specific needs. Additional phone consults will be available, but usually are only required if there are dosage complications [11].

NiTek’s patient guide [2] states thet virtual consultations are provided by Noemi Quintanar and Cheryl Kasdorf, whom the guide describes as “fully licensed and fully registered MEDICAL DOCTORS” and “also qualified (Duel Qualifications) as a Naturopath Doctor & a Allopathic Medical Doctor (GP).” [sic] Both are licensed naturopaths, but I can find no evidence either has a medical (MD) degree. Both offer remote treatment from their offices as well as through NiTek.

Regulatory Status

The FDA classifies devices according to the extent to which their use involves matters of life or death or serious injury and whether the device is entirely new or is similar to a previously approved device. To be legally marketed in the United States, the manufacturer must be registered with the FDA and its devices must be either approved, cleared, or exempted. The FDA Web site contains three searchable databases that can be used to investigate the status of a device.

  • The Establishment Registration & Device Listing database lists all companies and devices that are registered with the FDA. The search page warns that “Registration of a device establishment, assignment of a registration number, or listing of a medical device does not in any way denote approval of the establishment or its products by FDA.”
  • The Premarket Approval (PMA) database lists devices that have been approved based on substantial evidence that they are safe and effective for their intended uses. The evidence must include human clinical trials in addition to physical, scientific, biologic, and engineering tests.
  • The 510(k) Premarket Notification database. A 510(k) is a premarket submission made to FDA to demonstrate that the device is substantially equivalent to to a legally marketed device that does not need premarket approval. To meet this standard, the manufacturer must provide evidence that the device is at least as safe and effective as a previously cleared or approved device.
Neither NiTek nor the Thyroflex device is listed in the PMA or 510((k) databases. The device is merely registered as a percussion instrument (product code GWZ) that is repackaged or relabeled by Daag International, of Scottsdale, Arizona. FDA regulation 882.1700 states that a percussor is neurological diagnostic device that is “a small hammerlike device used . . . to provide light blows to a body part,” is “a diagnostic aid during physical examinations,” and is exempt from premarket notification procedures. The Arizona Corporation Commission Database indicates that Turner served as CEO and board chairman of Daag Medical Inc from 1999 through 2012 when it was administratively dissolved.


Most exempt devices are simple products such as bandages, tongue depressors, bedpans, dentures, orthopedic shoes, and other items in which failure is unlikely to cause serious harm. Devices that play a substantial role in diagnosis or treatment must either be cleared or approved. The reflex hammers covered by Regulation 882.1700 are simple devices, such as the one pictured above, which are used to tap muscles so the practitioner can see how much they contract when struck. They do not have electronic or software components and are not intended for diagnosing specific diseases or recommending treatment. Thus, although the standard hammer included in the Thyroflex package is exempt, the spring-loaded hammer and the system as a whole are not.

Thyroflex Asia has posted a titled “Certificate of Registration” to its site that, at first glance, might appear to have been issued by the FDA. But it is nothing more than a fancy certificate issued by a company that has no FDA affiliation and even states: “Any representation that creates an impression of official approval because of registration or possession of a registration number is misleading and constitutes misbranding. The U.S. Food and Drug Administration does not issue a certificate of registration.” (Click to read it.)

Prominent User Disciplined

Thyroflex’s most visible promoters include Prudence Hall, M.D. , who operates The Hall Center in Santa Monica, California The clinic’s Web site states that Thyroflex testing is used to “help diagnose subtle thyroid conditions.” [12] In 2008, she wrote to Turner:

On your recent visit to our practice. . . . We have been delighted with the results we have been obtaining with Dr. Rozlynn Myers, using the Thyroflex and Thyrodine to identify dose and titrate our patients for thyroid and iodine problems. Daryl, your testing devices have had a major impact on our patients over all well-being and health, which has been quite incredible to observe. The devices have taken away they guessing game of identifying, dosing and titrating using their serum blood tests. In addition we were selected to participate in the Dr. Phil TV show, which was aired in January, at which time we not only tested the participants on the show but also Dr. Phil, his wife Robin and the crew, to such a degree that our phones have been ringing off the hook, with referrals, all wanted to have the health issues addressed, and with your device we can with confidence take care of them [13]

The above-mentioned “Dr.” Myers is not a medical doctor. One of her Web sites states: Rozlynn has studied at the American University of Complimentary Medicine in California receiving a degree in Holistic Health and a certified Homeopathic Doctor.” [14] The American University of Complementary Medicine is a non-accredited school located in California. Toward the end of 2008, she left the Hall Center to open her own clinic—Thyroid Health Canada, in Toronto, Canada—which featured Thyroflex testing.

In about 2015, Hall wrote another note that is accessible through the Thyroflex Web site:

I have used the Thyroflex to test thyroid function for the past seven years in my medical practice. and it has revolutionized the way I manage thyroid disease. I used to rely only on blood tests to evaluate thyroid hormone levels but found them to correlate poorly with patient’s signs and symptoms. We have come to rely on 98% accuracy of the Thyroflex, with its close correlation to both patient’s symptoms and 24-hour thyroid urine testing. The addition of urine iodine testing with the Thyrodine has further expanded the tools I use to diagnose and treat patients. This one minute urine test accurately assesses patient’s iodine status, which is so vital and maintaining healthy thyroid functioning and breast cancer prevention. At our center we perform hundreds of Thyroflex and Thyrodine tests each month each month for many years proving the Thyroflex & Thyrodine to be an invaluable work-horse for all physicians [15]

In 2017, the Medical Board of California accused Hall of unprofessional conduct, negligence, and inadequate record-keeping in her management of two patients. Among other things, she was charged with treating patients unnecessarily for supposed hormonal problems even though they had normal tests or no relevant tests before the treatment was started [16]. In 2018, Hall signed a consent order under which was placed on probation for four years and required to undergo substantial additional training as well as monitoring of her practice. The board also barred her from supervising physician assistants or advanced practice nurses or representing herself as a specialist in obstetrics, gynecology, or hormone therapy [17].

The 2017 accusation does not mention the Thyroflex or its “Core Hormone Protocol” by name, but it notes that Hall based one patient’s diagnoses on “a patient questionnaire and a review of the blood laboratory analysis, with no physical examination (other than reflexes)” and that the patient wound up with excessively high blood levels of thyroid hormone. The accusation also notes that despite normal lab values for all of the sex hormones and adrenal hormones and no lab value for thyroid hormones, Hall prescribed estrogen, progesterone, DHEA, pregnenolone, vitamin D3, testosterone, thyroid replacement, and iodine for that patient. These are the very same hormones that the Core Hormone System promotes. The accusation states that between October 2011 and October 2014, the patient paid Hall more than $7,000 for hormone products.

Why I Am Skeptical

As noted above, Thyroflex marketers would like you to believe that hypothyroidism (thyroid hormone deficiency) is extremely common, that Thyroflex testing is more accurate than standard blood tests, and that these assertions are backed by scientific studies. I am very skeptical of these claims.

  • The standard way to look for hypothyroidism is to measure the blood levels of thyroid hormones and thyroid-stimulating hormone (TSH), which the pituitary produces when the thyroid gland is not making enough. Hypothyroidism may be either subclinical or overt. Subclinical hypothyroidism is characterized by a serum TSH above the upper reference limit in combination with a normal free thyroxine (T4) and no symptoms or mild symptoms related to the hormonal shortage. Overt (symptomatic) hypothyroidism is characterized by an elevated TSH, usually above 10mIU/L, combined with with a subnormal level of free T4. [18] The most important study, which was done between 1988 and 1994, found that in the United States, the prevalence of subclinical disease was 4.3% and overt disease 0.3% among 17,353 people age 12 or older [19]. The claim that the overall incidence is 80% is preposterous.
  • Thyroflex proponents claim that people with subclinical hypothyroidism are unaware that they have the condition, but suffer from the symptoms. NiTek’s symptom survey lists 23 symptoms that could be related to hypothyroidism, but most of the symptoms are common, all have other possible causes, and taking more thyroid hormone than you need can cause serious adverse effects. For his reason, people who want help with any such symptoms should seek appropriate medical diagnosis.
  • Some practitioners are listing symptoms from the symptom survey—such as tiredness; dry skin/hair; muscle cramps; poorer memory; depressed; puffy eyes; constipation; low libido; puffy hands and feet; slower thinking; and easy weight gaining—and advertising that if you have three or more of them you should have a Thyroflex test. With most of these symptoms, the proper way begin an evaluation is to take a proper history to narrow down the most likely causes.
  • For many years, the Thyroid & Adrenal Research Institute claimed that having just one of the above symptoms is enough and that ” if you ever been told you have high cholesterol, sugar, blood pressure, atherosclerosis, fluid retention (the need for diuretics), or anyone in your family has history of heart attack it is critical to determine whether hypothyroidism is an underlying factor.” [20]
  • The idea that thyroid function can influence reflex responses is correct. Before hormonal testing was available, testing of the Achilles reflex (performed by tapping the back of the ankle) was considered helpful for detecting and treating hypothyroidism. However, TSH testing has rendered it obsolete [21]. Demonstrating that Thyroflex testing is better than TSH testing would require a mountain of new evidence that includes clinical trials. Proving that Thyroflex’s treatment recommendations are superior to standard medical care would require additional clinical trials. NiTek claims that its methodology has been backed by clinical trials, but I could find no relevant research citations on its Web sites, no journal articles in the PubMed database authored by Konrad Kail or Daryl Turner, and no relevant studies listed in Clinical Trials.gov.
  • NiTek asserts that if a thyroid problem exists, attention must be also given to other “core hormones.” I haven’t seen the details of the NiTek’s “Core Hormone Protocol,” but NiTek’s literature suggests that the Thyroflex system enables practitioners to evaluate the status of many other hormones. I don’t believe that this is possible. It also concerns me that many of the people who administer Thyroflex testing lack the expertise needed to give proper medical advice.
  • I don’t know whether Thyrodine testing is accurate. But even if it is, is makes no sense to use it as a screening test in the United States or in other developed countries where dietary intake of iodide is adequate and iodine deficiency is rare [22].

For all of the above reasons, I believe it would be wise to avoid Thyroflex testing and those who recommend it.

  1. Thyroflex —The most advanced thyroid function test. Nitek Medical Home page, accessed Sept 15, 2018.
  2. The patient guide — Core hormone balancing. NiTek flier, March 2, 2017.
  3. In memoriam: Konrad Kail. Natural University of Natural Medicine Web site, July 18, 2011.
  4. About Thyroflex. Thyroflex Asia Web site, accessed Sept 18, 2018.
  5. Our staff. The Thyroid & Adrenal Research Institute Web site, archived Sept 13, 2008.
  6. Reflexometry and hormone function. Pub. No. 2007/0118046 Al. May 24, 2007.
  7. Home page. The Thyroid & Adrenal Research Institute, archived April 2, 2008.
  8. Thyroflex 4G Instruction Manual. NiTek Medical Inc., 2014.
  9. Welcome video by Dr. Turner. Accessed Sept 20, 2018. Click for transcript.
  10. Products & services. Thyroflex Asia Web site, accessed Sept 17, 2018.
  11. GP consultation protocol and request form, July 2008. Obtained from a cached TARI Web site page.
  12. Treatment protocol. The Hall Center Web site, accessed September 16, 2018.
  13. Hall P. Testimonial. Included in Nitek Startup Manual, July 3, 2018.
  14. Rozlynn Myers, HD: Homeopathic doctor, bio-identical hormone and thyroid expert, recent guest on the Dr. Phil Show. Thyroid Health Canada Web site, posted in 2008.
  15. Hall P. Letter to Daryl V. Turner, Jan 14, 2008.
  16. Accusation. In the matter of the accusation against Prudence Elizabeth Hall, M.D. before the Medical Board of California. Case No. 800-2015-010885, filed Sept 12, 2017.
  17. Stipulated settlement and disciplinary order. In the matter of the accusation against Prudence Elizabeth Hall, M.D. before the Medical Board of California. Case No. 800-2015-010885, adopted Aug 13, 2018.
  18. Garber JR and others. Clinical practice guidelines for hypothyroidism in adults: Cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocrine Practice 18:988-1028, 2012
  19. Hollowell JG and others. Serum TSH, T(4), and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). Journal of Clinical Endocrinology and Metabolism 87:489-499, 2002.
  20. Tchelidze T. Heart disease: What you need to know. TARI newsletter, Dec 2006, accessible from 2006 through 2012.
  21. GP consultation protocol and request form, July 2008. Obtained from a cached TARI Web site page.
  22. Iodine deficiency. The American Thyroid Association patient education brochure, May 28, 2018.

This article was revised on March 1, 2019.