[Etiology and prognosis of highly elevated C-reactive protein levels (≥500 mg/L): a retrospective study about 168 measures in a series of 113 patients].

Purpose: The C-reactive protein (CRP) is a useful inflammatory marker with a rapid kinetics during the inflammatory process. The objective of this study was to determine the etiology and prognosis of extremely elevated CRP values greater or equal to 500 mg/L.

Methods: We performed an exhaustive retrospective study from January 2004 to July 2009, in a general hospital, of all patients with a CRP value above 500 mg/L, admitted in all clinical departments. Clinical data were collected by a single observer using a standardized questionnaire.

Results: One hundred and sixty-eight CRP values greater or equal to 500 mg/L were identified amongst 106,758 tests (0.16%) corresponding to 113 patients: 51% were men and their mean age was 59.5 years. Mean CRP value was 561 mg/L (500-772). An immunocompromised condition was observed in 52% of the patients. All but 13 patients presented an infectious disease. Microbiological analysis of the infected patients identified 59 Gram-positive cocci (20 Staphylococcus spp., 35 Streptococcus spp. including 21 Streptococcus pneumoniae), two Gram-negative cocci, 48 Gram-negative bacilli (including 19 Escherichia coli), three Gram-positive bacilli, 16 fungal infections, one viral infection. Site of infection was respiratory in 63%, urinary in 17% and abdominal in 16%. At day 30, mortality rate was 27% and only 41% of the patients were discharged at home.

Conclusion: CRP value above 500 mg/L is highly related to bacterial infections, without over-representation of a given microorganism. One-month mortality is high (27%).