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[Normal D-dimer concentration in hospitalized patients with lung diseases].

INTRODUCTION
The use of D-dimer testing is an established part of the diagnosis of suspected pulmonary embolism (PE). However, in hospitalized patients many various factors might be responsible for increased D-dimer concentration and they could lower utility of D-dimer in exclusion of PE in such population. According to some published data, calculating the index D-dimer/fibrinogen could increase the specificity of D-dimer in the recognition of venous thromboembolism (VTE). The aim of the present study was to determine the frequency of normal D-dimer concentration in hospitalized patients with lung diseases in whom the differential diagnosis of PE is particularly difficult and to evaluate the utility of the index D-dimer/fibrinogen in subgroups of patients: with acute VTE and with lung cancer.


MATERIAL AND METHODS
619 consecutive patients aged 54.9 (± 15.4) hospitalized in reference pulmonary center were enrolled into observation. Among them, there were 96 (15%) patients with acute VTE, 65 (10%) with exacerbation of COPD and 172 (27%) with lung cancer.


RESULTS
Mean D-dimer concentration (Vidas D-dimer New) was 1956 ± 3691 ng/ml and median value 842 (45-35 678) ng/ml. Normal D-dimer concentration (〈 500 ng/ml) was found in 225/523 (43%) without acute VTE. In 49% (32/65) patients with COPD and in 25% (43/172) patients with lung cancer D-dimer concentration was below 500 ng/ml as well. The index D-dimer/fibrinogen was significantly higher in acute VTE patients compared to lung cancer patients - 808 ± 688 and 289 ± 260 respectively, p 〈 0.001.


CONCLUSIONS
Normal D-dimer concentration was found in more than 40% of patients with lung diseases hospitalized in reference pulmonary center. This observation could suggest higher than described in the literature utility of D-dimer measurement in exclusion of PE in such a population. The value of the index D-dimer/fibrinogen, which is significantly higher in acute VTE than in lung cancer requires further evaluation to establish its clinical utility.