Serum and ascitic procalcitonin levels in cirrhotic patients with spontaneous bacterial peritonitis: diagnostic value and relationship to pro-inflammatory cytokines.

OBJECTIVE

To assess the potential role of procalcitonin and pro-inflammatory cytokines, TNF-alpha, and IL-6, in the diagnosis of spontaneous bacterial peritonitis (SBP).

DESIGN

Prospective study.

SETTING

The emergency unit of a teaching hospital.

PATIENTS

We included 21 patients with SBP and 40 patients with sterile ascitic fluid.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

For the diagnosis of SBP, the best markers were serum levels of procalcitonin with a cut-off value of 0.75 ng/ml, a sensitivity of 95%, a specificity of 98%, and ascitic fluid levels of IL-6 with a cut-off value of 5,000 ng/ml, a sensitivity of 100%, and a specificity of 88%. C-reactive protein and serum polymorphonuclear count have low sensitivity/specificity at 62/92% and 57/90%, respectively. From 21 patients with SBP, ascitic fluid to serum ratio of TNF-alpha and IL-6 was greater than to 2 in all cases with a mean at 6.2 +/- 6.5 and 34 +/- 31, respectively. By contrast, this ratio for procalcitonin was less than 1 in all cases with a mean at 0.31 +/- 0.25. We found no correlation between procalcitonin levels and cytokine levels in either ascitic fluid or serum.

CONCLUSIONS

Serum procalcitonin level may become a useful marker for the diagnosis of SBP in cirrhotic patients. The low ratio of ascitic fluid to serum procalcitonin supports the hypothesis that procalcitonin is not produced intraperitoneally.