Curbside Consult with Dr. Jayne 3/24/25

Mr. H was correct in his assumptions around what I would think about Function Health, the celebrity-backed company that offers subscriptions to lab tests.

I checked out their website and the first thing that annoyed me was the use of “insights,” which has become quite the buzzword over the last few years. What exactly does “insights from top doctors” mean? Are they sharing high-quality, peer-reviewed research findings, or are these just their opinions? How do they even define “top doctors?”

Just looking at their “all-in-one for everyone” laboratory test menu makes me cringe. The vast majority of these tests haven’t been proven to be useful for screening average-risk people. Selenium testing, anyone? Selenium deficiency is extremely rare in the US and Canada, except among patients who are undergoing dialysis and occasionally in patients with HIV. But sure, let’s test everyone and hope for the best, and let the beleaguered primary care physicians sort it out when a patient’s results flag high or low in a clinically insignificant way.

News flash: although it looks like it’s included on their home page, it’s actually an add-on test that costs extra, which to me adds an element of bait-and-switch for the customers who aren’t going to do the six additional clicks needed to see the lists of tests.

Most patients don’t understand that “normal” lab values are defined statistically. For that reason, people will be outside the accepted range even though their levels are probably just fine for them as a human. In fact, we don’t really use the word “normal” for most blood tests – we use “in range” and “out of range” unless it’s a critical high or low. Back when I was in med school, the students at my university were used in a project to revalidate the reference ranges for cholesterol tests. I can guarantee that based on our eating habits, we probably weren’t the best population to use for that effort.

We often see confusion when patients look at the results of chemistry panels and their values are a decimal point above or below the cutoffs. Usually those calls result in a phone conversation that is at least 10 minutes long, which takes away time from patients with actual issues who need care.

Other labs included in their testing panels are ones that are tricky to interpret in the face of patients with symptoms, let alone when ordered on a patient with no symptoms. Immune-related labs are the most common of these and can be vexing to patients to the point where we in the primary care trenches only order them when we’re trying to rule a disease or condition in or out of our diagnostic process. They will be “out of range” or mildly abnormal in quite a few patients, which is why you want to avoid ordering them unless the results will change your diagnostic or management plan.

I’m sure that some patient engagement advocates have thoughts around this, but I’ve been in this exact patient scenario and encouraged my own physician to only order the tests that were specifically indicated. I didn’t want to go down any other diagnostic rabbit holes chasing spurious abnormalities that weren’t going to drive the management of my particular situation in a productive direction.

Also in this scenario, the patient has no idea of the education, training, or reputation of the physicians or midlevel providers who may be reviewing their results. I personally like to know who my providers are and where they trained to ensure they’re not low quality. There are plenty of random physicians who will literally do this kind of work for $8-$10 per chart regardless of their qualifications, so buyer beware.

The company also offers the Galleri multi-cancer detection test as another extra-fee add-on. This can be useful, but is best performed after a patient receives appropriate counseling to understand the implications of having been tested for certain conditions or of receiving non-negative results. There are supposed to be laws protecting us from genetic discrimination, but in reality there are plenty of ways in which they can impact a person negatively.

One sneaky trick is not asking patients for the results of their genetic testing, but asking if they’ve ever been tested for a particular condition and then using that information to negatively impact the insurance underwriting process. I’m not an attorney and don’t know if it’s legal, but I’ve seen it. And if you’re in the military and seeking certain job roles, the presence of testing can disqualify you even with negative results. I had to write an appeal letter for one of my patients in that situation, and unfortunately it was not successful. Alzheimer’s risk testing is another one that falls into this bucket.

Other add-on tests are those related to food allergies. Let me tell you about the case that happened in my home town, where a patient died as the result of inappropriately ordered food allergy testing. It’s been written up in the literature and I wasn’t a treating physician, so not a HIPAA violation for those who might be concerned.

The pediatric patient ate peanut butter daily with no issue. However, their physician ordered an overly broad food allergy testing panel that said they were allergic to peanut butter. The parents immediately banned peanuts from the house. Months later, the patient was exposed to peanuts elsewhere and had an anaphylactic reaction and died. How does that happen? The patient had been orally desensitized to the allergen through daily consumption, which protected them. (We actually do this now intentionally with kids with severe peanut allergies, starting with microdoses and working our way up.) When they stopped that daily protection, a life-threatening allergy was now in play. To summarize, a poorly considered lab test that never should have been ordered killed this child.

Although this offering is a subscription service that offers all this testing for one low price, guess who pays for all the follow up of the abnormal tests? You and I do, in the form of increased insurance premiums, since it’s almost certain that people who need additional testing and medical visits to explain it all will do so on their commercial or publicly funded coverage. We also pay for it through an increase in unnecessary visits to follow up these findings, which reduce access to those who actually need care.

I experienced this personally when I was in traditional primary care practice and Quest Diagnostics launched their direct-to-consumer testing site. The site mentions that “clinicians call you promptly if any urgent results arise,” but I’m betting those clinicians who are making the phone calls are medical assistants, patient care technicians, or medical secretaries and not actual licensed clinicians. I doubt there will be a physician on the other end of the line to answer your questions.

There are also some interesting findings in the FAQs, including that Function is considered “beta” and is “not yet fully developed” and “there will be rapid changes with occasional bugs.” This would not be allowed in mainstream electronic health record or laboratory management software in this day and age. They try to absolve themselves through a disclaimer that they are a healthcare tech company and not a medical or laboratory provider, and that all the real work is done by independent third parties.

The FAQs also note that the company is jumping on the AI bandwagon and “aims to apply machine learning algorithms to your lab test results over time, in order to uncover things that humans are likely to miss.” Regarding privacy, the site notes that patients can delete their data and no personally identifiable information will be shared, but it doesn’t address any concerns about them selling de-identified or otherwise aggregated data, which I would bet they are.

Like the commenters on Mr. H’s post, I’d also like to see a copy of the clinical summary and how they interpret unnecessary tests. Maybe we should start a HIStalk fund drive to sponsor a reader to sign up in exchange for sharing their experiences throughout the course of the year-long subscription.

What do you think about Function? Is Matt Damon’s endorsement enough to lure you in? Leave a comment or email me.

Email Dr. Jayne.