Variation in high-sensitivity C-reactive protein levels over 24 hours in patients with stable coronary artery disease

Limited, controversial data exist regarding changes in high-sensitivity C-reactive protein (hs-CRP) levels over short times and the importance of detecting these changes in patients who have coronary artery disease (CAD). We investigated the variation of hs-CRP levels and their association with the severity of CAD in patients with stable CAD.We measured morning, midday, evening, and midnight hs-CRP levels in 124 patients (94 with CAD, 30 with normal coronary arteries), who were evaluated via coronary angiography and Gensini scoring. Patients were divided into 3 groups (normal coronary arteries, mild CAD, or severe CAD) according to Gensini score.Temporal hs-CRP levels varied significantly--the highest mean concentrations were found in the morning, and the lowest concentrations at midday (P <0.001). All temporal hs-CRP measurements and the absolute increase in hs-CRP levels were significantly higher in patients with severe CAD (both P <0.001). The most significant predictors of CAD severity were age (P=0.005), midday hs-CRP level (P <0.001), and brain natriuretic peptide level (P=0.045). Receiver operating characteristic curve analysis showed that cutoff values of hs-CRP taken at different times predicted severe CAD with similar sensitivity and specificity. Different cutoff values for temporal hs-CRP levels correlated with the severity of CAD. Serum levels of hs-CRP varied over 24 hours, whether patients had CAD or normal coronary arteries.