hs-CRP 4.2 mg/L — what does it mean?

What this test is

A sensitive measure of low-grade inflammation in your body.

What your number means

Under 0.8 is the target and 1.0 is the first flag. The 1–3 stretch is the one almost nobody discusses — your lab prints ‘normal’, yet sustained inflammation in that band is linked to your body ageing measurably faster. Over 3 is a strong signal. One caveat: an infection, injury or very hard workout in the past week can lift this temporarily, so a single high reading is always worth repeating.

Why it matters

Chronic, silent inflammation is the single biggest environmental driver of ageing — it slowly wears down the neighbourhood your cells live in.

Your cells live in a ‘neighbourhood’. hs-CRP is like a smoke detector for that neighbourhood — a low reading means clean air; a high one means something is burning and the cells are being damaged over time.

What to do about it

Make sure the test ordered is the high-sensitivity version — ordinary CRP can’t see this range at all. Sleep, weight around the middle, gum health, movement and cutting ultra-processed food all move it. Retest six to twelve weeks later, when you’re well.

Where it sits in your Body Age

hs-CRP (High-Sensitivity CRP) is one of the tests behind Hidden Inflammation — How much quiet, low-grade inflammation is wearing your body down in the background. It is one of four areas that together give a single number: the age your body reads, next to the age on your birth certificate.