Very low C-reactive protein in apparently healthy individuals: physiological status or just a reflection of an improved health profile

The objective of our study was to determine whether the very low concentrations of C-reactive protein (CRP) detected by high-sensitivity CRP (hs-CRP) assays that one encounters from time to time in apparently healthy individual represent a physiological status or are just a reflection of an improved general health profile. The concentration of hs-CRP was determined by using the Behring BN II nephelometer. The arbitrary cut-off point of hs-CRP (≤0.16mgl^-1) was determined at the lower detection level of the assay. A total of 6588 apparently healthy individuals were screened following exclusion of recent infection/inflammation by using a detailed questionnaire. One hundred and sixty (2.4%) individuals out of the above-mentioned cohort presented hs-CRP concentrations of ≤0.16mgl^-1. They were found to be significantly younger and lean, had an improved lipid profile and an attenuated acute-phase response in terms of lower erythrocyte sedimentation rate and fibrinogen concentration as well as white blood cell count. In addition, these individuals had less atherothrombotic risk factors, except for smoking habits which were as frequent as in those of individuals with a higher hs-CRP concentration. After calculating the concentration of this biomarker following multiple adjustments, the individuals with very low CRP remained with a very low value despite the multiplicity of the adjustments. We raise the possibility that this particular low concentration might represent a physiological status and is not necessarily a result of the improved general health profile per se.