Measurement of lactate in ascitic fluid: an aid in the diagnosis of peritonitis with particular relevance to spontaneous bacterial peritonitis of the cirrhotic.

Lactate concentrations were measured in the ascitic fluid of patients using the Monotest Lactate Kit, an inexpensive, reliable bedside test that gives results within 15 min. The values were significantly higher in 24 patients with proven bacterial peritonitis, eight of them with spontaneous bacterial peritonitis, than in 53 patients with uninfected ascites of various other etiologies. In only two patients from the latter group, both with hepatic carcinoma and peritoneal metastases, were the values in the range found in bacterial peritonitis. Lactate determination was at least as sensitive as measurement of WBC levels for diagnosing peritonitis. Serial determinations in two patients with peritonitis showed declining values as the disease responded to treatment. The test has particular relevance for patients with spontaneous bacterial peritonitis, because this disease, which is potentially life-threatening although frequently asymptomatic, requires immediate treatment, yet currently depends on time-consuming culture procedures for diagnosis.