The predictive value of serum procalcitonin levels in adult patients with active pulmonary tuberculosis.

The aim of our prospective study was to evaluate the predictive value of serum procalcitonin (PCT) level in comparison with C-reactive protein level and erythrocyte sedimentation rate for the diagnosis of pulmonary tuberculosis (PTB) on admission and 6 months after the administration of anti-tuberculous chemotherapy (ATCT). Seventy-five adult male patients with active PTB who were mycobacteriologically diagnosed (smear and culture positivity) were examined in this study. As a control group, 75 healthy adult males were enrolled. The measured serum PCT levels were within the normal range both in healthy individuals and in patients 6 months after ATCT. Serum PCT levels had been slightly high on admission in patients with PTB in comparison with controls (P = 0.01) and patients who had ATCT (P = 0.001), and this difference was statistically significant, but the PCT levels of most cases with PTB (58.7%) were below the usual cut-off level (0.5 ng/mL). We conclude from this study that the serum PCT level was not a reliable indicator in the diagnosis of active PTB because of its low sensitivity (41.3%), and in most cases it was not capable of overcoming the cut-off level even if statistically meaningful results were obtained. The PCT test for the presumptive diagnosis of PTB cannot be substituted for microbiological, epidemiological, clinical and radiological data.