Homocysteine: a new diagnostic marker in spontaneous bacterial peritonitis.

BACKGROUND AND AIMS: The diagnosis of spontaneous bacterial peritonitis (SBP) depends primarily on a polymorphonuclear leukocyte cell count more than 250/mm. This method is invasive, and not diagnostic in all variants of SBP; we aimed to assess serum homocysteine as a precise indicative marker for the diagnosis of all variants of SBP.

PATIENTS AND METHODS: A total 323 consecutive ascitic patients were registered in this prospective work. Serum and ascitic fluid of homocysteine were evaluated utilizing an enzyme-linked immunosorbent assay.

RESULTS: Participants were classified into a non-SBP group, including 262 participants and 61 patients with SBP. Serum and ascitic homocysteine were considerably elevated in the SBP group than in the non-SBP group (17.94±7.57 vs. 11.75±5.68 μmol/l; P<0.001 and 14.70±5.45 vs. 9.75±4.55 μmol/l; P<0.001). At a cutoff value of 17.79 μmol/l, serum homocysteine had 89.3% specificity and 95.1% sensitivity for distinguishing SBP (area under the curve: 0.932) and, at a cutoff value of 16.1 μmol/l, ascitic homocysteine had 84.4% specificity and 92.7% sensitivity for distinguishing SBP (area under the curve: 0.901). Both were positively correlated with the polymorphonuclear count, C-reactive protein, Child-Pugh score, and Model For End-Stage Liver Disease score as well as negatively correlated with the protein content in the ascitic fluid and estimated glomerular filtration rate. After SBP therapy, there was a marked reduction in serum and ascitic homocysteine levels.

CONCLUSION: This study demonstrates that serum and ascitic homocysteine are considerably higher in SBP participants versus non-SBP patients. Serum homocysteine may provide a reliable and noninvasive diagnostic marker for all variants of SBP.