Testing & Screening

Which tests change what you do — and which just find something to worry about.

Testing feels like the responsible thing to do, which is why it sells so well. But a test only helps if the result would change what you do, and a surprising number of popular tests can't clear that bar — while carrying real costs in false positives, incidental findings, anxiety and downstream investigation.

We run a blood-testing page ourselves, so we'll be direct: these pages exist to tell you when testing isn't indicated. No advertising or product recommendations appear anywhere in this section, by rule.

Guides