Urinary procalcitonin associated with a microbiologically diagnosed pneumonitis: preliminary results

Full text

Procalcitonin (PCT), the prohormone of calcitonin, is a 116 amino-acid protein stimulated by bacterial inflammation and produced by neuroendocrine cells of different organs, included the lung. Elevated serum levels of PCT have been found in several diseases such as sepsis syndromes, inhalation burn injury, infectious pneumonitis. PCT has been measured in body fluids other than serum in only few papers and with conflicting results. The aim of the present study was to verify whether PCT levels measured in the serum, urine, and bronchoalveolar lavage (BAL) fluid could be a marker of pulmonary infection, diagnosed by a positive cultural bacterial exam in the bronchial washing (BW).

Until now, 10 patients with pulmonary diseases were studied. Four of them had a radiologically diagnosed pneumonitis, 3 had a non-small cell lung cancer (NSCLC), 3 had other non-infective lung diseases. All the patients underwent a flexible fiberoptic bronchoscopy (FOB) with BAL and BW. The quantitative determination of PCT was performed in the serum, urine and BAL fluid by the immunoluminometric assay (ILMA) using the LUMItest PCT kit (BRAHMS Diagnostica, Berlin, Germany).

PCT was not detectable in BAL fluids of all the patients. A positive determination of PCT was obtained in a total of 4 patients : in 2 of them in urine, in 1 patient in both urine and serum, and in 1 patient in serum. A trend towards a significant association between smoking habit and urinary PCT was found (PCT = 0 in non-smokers, 0.73 ± 1.27 ng/ml in ex-smokers, 1.77 ± 2.06 ng/ml in smokers). Urinary PCT was lower in patients with a radiologically diagnosed pneumonitis than in patients with NSCLC (0.95 ± 1.90 vs 1.83 ± 1.68 ng/ml, respectively). However a positive coltural exam for bacteria in BW was found in only 1 out of 4 patients with a radiologically diagnosed pneumonitis and in 2 out of 3 patients with NSCLC. Condidering the 3 patients with a positive coltural exam for bacteria in BW, a trend towards a significant higher urinary PCT values was found in these patients in comparison with the 7 patients with a negative coltural exam (1.83 ± 1.68 vs 0.54 ± 1.43 ng/ml, respectively). The 4 patients with a positive determination of PCT in urine and/or serum had a significant higher number of total cells in the BAL fluid in comparison with the remaining 6 patients (218 000 ± 155 000 vs 60 000 ± 30 000 respectively, P = 0.01).

In conclusion, these preliminary results seem to indicate that an increased level of urinary PCT is associated with the presence of pulmonary infection also complicating other lung diseases such as NSCLC and demonstrated by a positive coltural exam for bacteria in BW. Urinary PCT reflects the severity of alveolitis which usually derives from pulmonary infection. Taking into account the smoking habit of the patient, urinary PCT could be a simple and non-invasive marker useful in the follow-up of patients with a microbiologically diagnosed pneumonitis.