High concentration of lactic dehydrogenase in small volumes of ascites.

During routine computed tomography and magnetic resonance imaging studies, small volumes of ascites may be detected in patients without liver cirrhosis or gross peritoneal dissemination of cancer. Additionally, transvaginal ultrasonography of the Douglas pouch makes sampling of peritoneal ascites technically easy. It is often necessary to sample the ascites to rule out peritoneal carcinomatosis (exudative ascites EA). In addition, certain disorders such as liver failure can result in transudative ascites (TA). Various methods of analysis of ascites fl uid are available to distinguish exudative and transudative ascites. Cytological examination of ascites fl uid is specifi c but has a high falsenegative rate [1]. In addition, cytologic analysis requires considerable time and is not widely available. Therefore, we investigated other conventional parameters for analyzing ascites fl uid including levels of total protein (TP), lactic dehydrogenase (LDH) or total cholesterol (T-cho). The presence of small amounts of physiological ascites can be seen in healthy men and women [2]. However, no studies have reported on the levels of these values in physiological ascites. Therefore, the purpose of this study was to determine if measurements of TP, LDH, and T-cho could be used to differentiate among exudative, transudative, and physiological ascites. Transudative ascites from 8 patients with hepatic failure and EA from 9 patients with peritoneal carcinomatosis were obtained by a percutaneous approach or paracentesis. Physiological ascites (PA) were obtained from 9 patients with early gastric cancer (final pathology T1NO, no patients with peritoneal recurrence during follow up periods after operation) upon entry into the abdomen for surgical exploration. Note that these patients did not have any evidence of gross peritoneal dissemination of their cancer nor did they have any pain or symptoms. Laboratory values of TP, LDH, and T-cho in the ascites fl uid from transudative, exudative and physiologic samples were measured. As shown in Fig.1, TP and T-cho levels in physiological ascites were similar to levels in malignant ascites. However, LDH levels were 104 ± 41 (TA), 322 ± 78 (EA), and 2612 ± 498 (PA) U/l. LDH level of physiological ascites was approximately eight times higher than that of exudative ascites. The usefulness of measuring LDH, T-cho, and TP in ascitic fl uid for differentiation of exudative and transudative ascites has been reported [1, 3]. According to the criteria in previous reports, sensitivity and specifi city for LDH are 90-85% and 89-79% (cut off value 200-130 U/l), for T-cho 90-87% and 82-67% (45-31mg/dl), and for TP 90-83% and 75-68% (2.8-2.5 g/dl), respectively (Fig. 1). However, our results show that patients with PA were classifi ed as having EA according to the traditional parameters. The reason why PA has such high levels of LDH is not clear.