When you hear hoof beats, think of horses not zebras, is the aphorism coined in the 1940s by Theodore Woodward to explain that common conditions occur commonly and rare ones rarely. Most physicians involved directly in patient care will have seen the occasional “zebra” blood test result that is so unexpected when taken into clinical context that it is probably spurious, rather than the harbinger of some exotic lethal disease. Rational and cost effective use and interpretation of laboratory testing is perceived to be good medicine, and this particular skill is honed with experience. Also, when screening for disease, Public Health England is very clear—a screening programme needs to offer more benefit than harm and at a reasonable cost.

In the United States, where patients increasingly see themselves more as consumers, the mindset is somewhat different. It is now possible to go online and order a variety of blood tests without the need for a physician “order,” although the interpretation of the results is left to the patient/consumer laboratory. So called “at-home diagnostics” are a growing part of the US healthcare market, tapping into demand from patients who want to monitor their health outside of the traditional doctor’s office.

For some, this is seen as empowerment: individuals can choose to have a blood test performed even if it is thought unnecessary or unhelpful by their personal medical practitioners. Apparently, thyroid function testing is particularly popular. Many states in the US already allow patients to order certain blood tests without a request form signed by a physician. Recently, in Arizona, a law was passed expanding this “right” to allow Arizonians to obtain and pay for any laboratory test without first being required to obtain a healthcare provider’s request or approval by their health insurance company—all costs for the tests are considered to be out-of-pocket rather than paid for by an insurer.

Unsurprisingly, one new and very high profile company believes this law could serve as a model for the whole of the United States—“changing the healthcare paradigm to one in which early detection and prevention become reality.” This particular company has expanded rapidly across the state, creating “Wellness Centers at convenient hours” with prices that are 50-80% below the standard Medicare reimbursement rates.

Direct access testing certainly appears to be gaining in popularity, with the reasons including convenience, lower cost, privacy, more rapid access, and being prepared for a forthcoming visit to the doctor. For the US, the Arizona experience also offers access to certain tests that may have been restricted previously by insurance companies. The flip side is that there is no requirement to review results with physicians, nor any assurance that tests requested by patients are appropriate, or that patients are able to reliably interpret test results on their own. Patients who order their own tests might also not be able to contextualise the tests in relation to their personal medical history, fuelling the number of worried-well if a “zebra blood test” is reported. Although the labs performing the tests will in the most part be regulated, there is also the potential for “disease mongering” by commercial companies with vested interests now that consumers have easy access to low cost testing.

Is the NHS ready to adopt a similar system, where low cost blood testing is made generally available to consumers? This may be seen as another step along the road to privatisation although, given the explosion in the use of wearable technologies for fitness, lifestyle, and (increasingly) physiological monitoring, this approach may be attractive to an increasing number of people. It may also be helpful for patients to be given information about the real costs of laboratory investigations, rather than them being thought of as “free.” Whatever else, this new approach to blood testing would mean a shakeup of NHS laboratory and phlebotomy services, as well as the extinction of the long queues and prolonged waiting times at surgeries and hospital laboratories that are commonplace today.

David Kerr has worn many hats, sometimes at the same time—diabetologist; editor of Diabetes Digest; researcher; and founder of VoyageMD.com, a free service for travellers with diabetes, and Excarbs.com, which focuses on exercise and insulin. He is now director of research and innovation at the William Sansum Diabetes Center in Santa Barbara, California. You can follow him on Twitter (@GoDiabetesMD) and LinkedIn.

Competing interests: The author has no relevant competing interests to declare.