What's the difference between regular CRP and hs-CRP? Which one should I order?

Regular CRP and hs-CRP measure the same protein, C-reactive protein, but with assays calibrated for different ranges. Standard CRP detects meaningful elevations in acute illness, typically above 10 mg/L. The hs-CRP assay is calibrated to detect values between 0.1 and 10 mg/L with much greater precision. For cardiovascular risk assessment, the clinically meaningful range is 0.5 to 5 mg/L, entirely invisible to a standard CRP test.

If you order "CRP" without specifying "high sensitivity," the lab result you receive cannot detect the cardiovascular signal you are looking for. A standard CRP that returns "within normal limits" (<10 mg/L) in a man whose hs-CRP is 3.8 mg/L has told you nothing useful. Always specify hs-CRP when ordering for cardiovascular risk purposes. When ordering through direct-to-consumer labs, search specifically for "high sensitivity CRP" or "hs-CRP." The cost difference is negligible; the information difference is clinically significant. (Pearson et al., Circulation, 2003)

Cardiologist's calibrated position, Solid (1) for hs-CRP as the correct assay. This is not a nuance, it is the difference between useful data and false reassurance.

What to do: When ordering labs for cardiovascular assessment, always specify "high sensitivity CRP (hs-CRP)." If your previous "CRP" result was reported as a single number without a decimal place or showed as simply "normal/abnormal," it was likely a standard assay.

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