Why a normal report isn’t the whole picture

A lab’s reference range is usually built so that about 95% of a reference population falls inside it. So “normal” means you sit among most people, on the day you were tested.

It doesn’t tell you which way you’re heading. A marker can climb for years and stay inside the range the whole time. Seen once, it looks fine. Seen as a line, it’s the start of a conversation.

That’s the idea behind preventive care: read your own trend, against your own normal, early enough to act on it with your doctor.