The diagnostic significance of
procalcitonin concentrations in lower
respiratory tract infections and
tuberculosis is not known. A prospective analysis was, therefore, performed in patients with acute exacerbation of
chronic bronchitis (AECB), community-acquired
pneumonia (CAP),
hospital-acquired pneumonia (HAP) and
tuberculosis and their
procalcitonin levels compared with those of patients with noninfectious
lung diseases (controls). In addition, standard inflammatory parameter data were collected. A prospective clinical study was performed with four different groups of patients and a control group that consisted of patients with noninfectious
lung diseases. A total of 129 patients were included: 25 with HAP, 26 CAP, 26 AECB, 27
tuberculosis, and 25 controls.
C-reactive protein level, blood cell counts and
procalcitonin concentration were evaluated on the first day after onset of clinical and inflammatory symptoms prior to treatment. The median
procalcitonin concentrations in HAP, CAP, AECB and
tuberculosis were not elevated in relation to the cut-off level of 0.5 ng x mL(-1). In the HAP group, in four of five patients who subsequently died,
procalcitonin concentrations of >0.5 ng x mL(-1) were found. In acute lower
respiratory infections, such as HAP, CAP and AECB, significantly elevated levels were found in comparison to the control group, but below the usual cut-off level. No differences were observed between
tuberculosis and the control group. Relative to the current cut-off level of 0.5 ng x mL(-1),
procalcitonin concentration is not a useful parameter for diagnosis of lower
respiratory tract infections. However, compared to the control group, there were significantly elevated levels in patients with
hospital-acquired pneumonia, community-acquired
pneumonia and acute exacerbation of
chronic bronchitis below the current cut-off level, which should be further investigated.