Function Health, the direct-to-consumer lab-testing company, announced today a $298 million Series B at a $2.5 billion valuation, bringing its total raised to about $350 million. The product is a membership: more than 160 blood tests a year, drawn at a national lab chain's roughly 2,000 locations, with results explained in an app. The price has just dropped from $499 to $365, the company says it has run 50 million tests, it is adding whole-body MRI from $499, and today it launched an AI assistant to interpret your results. The pitch is that you should know everything about your body. The business is what happens after you do.
The arithmetic of 160 tests. A laboratory reference range is, by convention, the interval that contains 95% of results from healthy people. That means a healthy person has roughly a one-in-twenty chance of landing outside the range on any single test, by chance alone. Run 160 tests on that same healthy person and the expected number of out-of-range results is about eight. Those eight flags are not a diagnosis. They are the statistical cost of testing everything, and they are also, commercially, the most valuable thing the panel produces — because each one is a reason to retest, to add a test, to book a scan, to ask the assistant, to stay a member. The company did not invent the arithmetic. It built a business on it.
Loree’s takeI spend a growing share of my practice un-worrying healthy people about numbers a panel flagged. A mildly off value, retested in six weeks, is normal more often than not; a trend across years in one marker means something, and a single reading rarely does. The company's materials present 160 numbers as knowledge. In my office they are 160 questions, most of which have the same answer: nothing, yet. The person who needs this panel least is the healthy person it is sold to. The person who needs a few of these tests most often cannot afford the membership.
Ben’s takeLook at the sequence of today's announcement: cut the price, add imaging, add an AI to talk to you about your results. That is a funnel. The membership is the entry fee; the flags are the engagement; the scan and the retest are the revenue. Investors did not value this at $2.5 billion because people need 160 tests. They valued the recurring anxiety a panel like this reliably generates in the people who can afford it. I have seen this model work. That is not a compliment.
Why it matters to a recovering optimizer. There is a short list of blood tests with good evidence behind them for a healthy adult, and your primary care clinician orders them. Everything beyond that list produces more flags than findings. The question to ask of any panel is not "what might I learn?" but "what would I do differently with the result?" For most of the 160, the honest answer is nothing, and the company's model depends on you not asking.
Before any test, ask: what would I do differently with the result? If the answer is nothing, skip the test.
This post reports on evidence and expert disagreement. It is not medical advice; decisions about treatment belong with you and your clinician.