Usefulness of serum procalcitonin levels in pulmonary tuberculosis

There are very few data on serum procalcitonin (PCT) levels in pulmonary tuberculosis (PTB) patients who are negative for HIV. We assessed serum PCT in consecutive patients diagnosed with pulmonary tuberculosis or community-acquired pneumonia (CAP) on admission to discriminate between PTB and CAP, and examined the value of prognostic factors in PTB. 102 PTB patients, 62 CAP patients, and 34 healthy volunteers were enrolled. Serum PCT in PTB patients was significantly lower than in CAP patients (mean ± sd 0.21 ± 0.49 versus 4.10 ± 8.68 ng·mL⁻¹; p < 0.0001). By receiver-operating characteristic curve analysis, serum PCT was an appropriate discrimination marker for PTB and CAP (area under the curve 0.866). PTB patients with ≥ 0.5 ng·mL⁻¹ (normal cut-off) had significantly shorter survival than those with < 0.5 ng·mL⁻¹ (p < 0.0001). Serum PCT is not habitually elevated in HIV-negative PTB patients and is a useful biomarker for discriminating between PTB and CAP; however, when serum PCT is outside the normal range, it is a poor prognostic marker.