Do you use medical or health monitors at home, or apps on a smartphone? Do you know if they are regulated by the government?

mHealth is making easier to be proactive about your own health, and to take a significant role in monitoring it. Along with the benefits of this hands-on approach, however, this trend carries risks from the limited knowledge that patients have about such devices relative to medical professionals.

In the United States, medical devices are regulated by the Food and Drug Administration (FDA). The FDA’s definition of a medical device is wordy and convoluted: “an instrument, apparatus, implement, machine, contrivance, implant, in vitro reagent, or other” thing that meets any of three criteria:

• Intended to diagnose, cure, treat, prevent, etc. diseases or other conditions

• “Intended to affect the structure or any function of the body” but not through metabolism or chemical action (which would classify it as a drug, regulated separately)

• The FDA says so

This covers all the obvious, serious medical equipment like X-ray machines, surgical apparatus, contact lenses, and hypodermic needles. On the less significant items, the distinction can seem more arbitrary. If a doctor examines you for strep throat, the tongue depressor she uses, a small variation on what is likely the oldest tool used by humans, is a regulated medical device. A pedometer on your smartphone? Not regulated.

Mobile medical apps themselves can be regulated; the FDA released guidelines in 2011 for such apps. An app qualifies as a medical device if it serves as an accessory to a device that is already regulated or if it transforms the mobile device into a medical device by causing it to meet the original criteria.

Of particular interest for mobile devices are physiological monitors and the sensors that they use, like pedometers, glucometers, and heart rate monitors. The question of regulation such was addressed in a meeting between Apple and the FDA, notes on which were recently released through a Freedom of Information Act request.

In the FDA’s notes, they stress that the intended purpose of the device is critical. If it relates to a particular disease or condition, nearly anything can be a medical device; if not, regulation is unlikely. If a blood glucometer, which measures blood sugar, is intended to be used by diabetics to monitor their condition, it is regulated. However, the FDA pointed to glucometers as an example of sensors that could be unregulated if designed and marketed for a non-medical purpose like nutrition.

This guidance opens the door for a host of non-regulated quasi-medical sensors. Much of mHealth technology is explicitly designed for general health and wellness, though some companies are tackling legitimate medical treatment.

Essentially this means that users should assume a personal health sensor or app is unregulated unless the manufacturer states otherwise. Caution when using unregulated health products is wise; regulation ensures accuracy and privacy, and unregulated products may offer neither.