The Ratio of Ascites Calprotectin to Total Protein is a Diagnostic and Prognostic Marker for Spontaneous Bacterial Peritonitis in Liver Cirrhosis

The occurrence of ascites in cirrhotic patients is a frequent event (about half of these patients developed ascites after 10 years of evolution) and marks an evolutionary turning point in the natural history of cirrhosis (30% survival at 5).

The spontaneous bacterial peritonitis (ISLA) is the leading infectious complication cirrhotic patient (prevalence of 10-30%). Half of these ISLA are already present on admission of the patient and over 20% of these infections are totally asymptomatic. The delay processing of ISLA causes heavy mortality. Even when antibiotic treatment is started immediately after the diagnosis of ISLA, in-hospital mortality remains high (about 20%) and mainly related to the development of severe sepsis, septic shock and hepatorenal syndrome; the medium-term prognosis remains severe as also survival after an episode of ISLA is 30-50% at 1 year. Therefore, the surviving patients with a first episode of ISLA are candidates for liver transplantation. Given the major prognostic implications and the asymptomatic nature of these infections, examination of ascites with neutrophil count (ANC) and bacteriological cultures still recommended during any puncture, which increases support. This is why clinicians are sensitive to processes that simplify the diagnosis of ISLA or make it faster.

The measurement of calprotectin in ascites could be of major interest for the rapid diagnosis of ISLA. It is a glycoprotein of 36 KDa fixing calcium and zinc, synthesized by neutrophils (where it represents 60% of the soluble proteins from the cytosol) as well as monocytes and macrophages in the lower concentration. It has anti-bacterial and anti-fungal, immunomodulatory and pro-apoptotic. Its synthesis is increased in case of inflammation and its rate reflects, in inflammatory bowel disease, the severity of the inflammation of the bowel wall. Fecal calprotectin allows to discriminate inflammatory bowel disease (IBD) functional impairment of the gastrointestinal tract (irritable bowel syndrome) in symptomatic patients and also seems more powerful than other non-specific markers of inflammation (CRP, sedimentation rate, leukocytosis) to make this distinction; again, this biological marker allows therapeutic monitoring for patients with IBD.

The reference technique proposed by the laboratory for assaying BÜHLMANN calprotectin is a quantitative ELISA in a stool sample or ascites but the Quantum Blue® Reader offers a faster quantitative measure (in 12 minutes). It consists of a sandwich immunoassay including the speed could be advantageously used for the diagnosis of ISLA. However, few studies have evaluated the assay of plasma calprotectin or in ascites in cirrhotic patients. A high plasma concentration of calprotectin could have a prognostic value in alcoholic cirrhosis, as a high concentration of calprotectin in ascites in decompensated cirrhosis.