C-reactive protein in the diagnosis of deep vein thrombosis.

The role of C-reactive protein (CRP) in the diagnosis of suspected deep vein thrombosis (DVT) and a possible advantage of its additional evaluation with D-dimer has not been clearly evaluated. We therefore studied plasma CRP and D-dimer levels in 233 consecutive patients with suspected DVT; the final diagnosis was based on the results of colour duplex ultrasound or venography. DVT was diagnosed in 31.3%. CRP and D-dimer correlated significantly (r = 0.64, P < 0.01); both were increased significantly in patients suffering from DVT (P < 0.001). Multivariate analysis revealed a significant influence of the presence of DVT (P < 0.001), the presence of malignancy (P < 0.001) and the presence of inflammatory diseases (P = 0.009) on plasma CRP, while there was no significant influence of the duration of symptoms (P = 0.30). The sensitivity (75% vs 93%) to specificity (69% vs 55%) relationship showed inferior results for CRP compared with D-dimer; its additional evaluation did not improve the diagnostic value of D-dimer. We conclude that CRP can provide additional information neither for the diagnostic process in patients with suspected DVT nor for the differential diagnosis of DVT and inflammatory diseases.