Chris Zahner: Why Healthy People Can Have Abnormal Lab Results
Chris Zahner, Former Clinical Pathology Medical Director (Chief of Clinical Pathology) at The University of Texas Medical Branch, shared a post on LinkedIn:
“You can be perfectly healthy and still have an ‘abnormal’ lab result. In fact, imagine we measure about 20 completely independent things, each with a reference interval containing 95% of healthy people.
Even if you are stone cold normal, there is about about a 65% (64.15% actually) chance that at least one of those results will fall outside its reference interval.
Of course, real laboratory tests aren’t completely independent. But the thought experiment exposes something important: Unusual does not necessarily mean unhealthy.
Yet patients increasingly receive laboratory results directly, often with a red H or L attached, and very little context about what that flag actually means.
A reference interval tells us something about how you compare with a population. It does not automatically tell us whether you have a disease.
Aakash and I got into this on this week’s LabReflex, including why we use 95% in the first place and whether there might be a better way to report laboratory results.”
Proceed to the video attached to the post.
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