Serum angiotensin converting enzyme activity in evaluation of patients with liver disease

Ductopenia related liver sarcoidosis

Sarcoidosis is a systemic granulomatous disease which may involve many organs. In approximately 95% of patients there is liver involvement, with noncaseating hepatic granulomas occurring in 21 to 99% of patients with sarcoidosis. Liver involvement is usually asymptomatic and limited to mild to moderate abnormalities in liver biochemistry. The occurrence of jaundice in sarcoidosis is rare; extensive imaging procedures and the examination of liver biopsies permit a precise diagnostic. Ductopenia associated with sarcoidosis has been reported in less than 20 cases and can lead to biliary cirrhosis and liver- related death. We report here on a case of ductopenia-related sarcoidosis in which primary biliary cirrhosis and extrahepatic cholestasis have been carefully excluded. The patient follow up was 8 years. Although ursodesoxycholic acid appears to improve liver biochemistry it does not preclude the rapid occurrence of extensive fibrosis. A review of the literature of reported cases of ductopenia related to sarcoidosis is provided.

Serum angiotensin converting enzyme and C4 protein of complement as a combined diagnostic index in alcoholic liver disease

Diagnosis of liver cirrhosis relies on hepatic biopsy. So far, attempts have failed to achieve a serologic test that differentiates cirrhosis from other hepatic conditions. The aim of this work was to assess the diagnostic value of the ratio of serum angiotensin converting enzyme activity (SACE) and the levels of protein C4 of serum complement (SACE/C4) in differentiating cirrhotic from noncirrhotic alcoholic liver diseases. In this study, 68 active alcoholic patients (17 with fatty liver or minimal changes, 11 with acute alcoholic hepatitis and 40 with cirrhosis) were included. Twenty healthy subjects were studied as a control group. Liver biopsy was performed in all patients. SACE levels were significantly higher in the group with cirrhosis when compared with the group of patients without cirrhosis and the control. On the other hand, serum C4 level decreased as liver damage progressed. SACE values above 25 IU/l had a sensitivity of 92.5 percent (95 percent confidence interval, 87.5 to 97.5) and a specificity of 79 percent (95% percent confidence interval, 70.5 to 87.5), in detecting those patients with liver cirrhosis. The sensitivity further increased to 95 percent (95 percent confidence interval, 90.5 to 99.5) and the specificity to 100 percent when the SACE/C4 ratio was used and a cutoff point of 145 was chosen. To conclude, in alcoholics SACE is specifically elevated in patients with cirrhosis, and the SACE/C4 ratio is a excellent biochemical index for the diagnosis of cirrhosis in alcoholic patients.

Angiotensin-converting enzyme: clinical applications and laboratory investigations on serum and other biological fluids

Angiotensin I-converting enzyme (ACE) is a peptidyldipeptide hydrolase that is located mainly on the luminal surface of vascular endothelial cells but also in cells derived from the monocyte-macrophage system. Physiologically, ACE is a key enzyme in the renin-angiotensin system, converting angiotensin I into the potent vasopressor angiotensin II and also inactivating the vasodilator bradykinin. Increased serum ACE activity (SACE) has been reported in pathologies involving a stimulation of the monocytic cell line, primarily granulomatous diseases. Sarcoidosis is the most frequent and the better studied of these diseases; high SACE is not only a well-established marker for the diagnosis but is also a useful tool for following its course and evaluating the effect of therapy. SACE can also be increased in nonsarcoidotic pulmonary granulomatous diseases such as silicosis and asbestosis, in extrathoracic granulomatous pathologies such as Gauchers disease and leprosis, and, to a lesser extent, in nongranulomatous disorders such as hyperthyroidism or cholestasis. On the other hand, monitoring sarcoidosis obviates the measurement of ACE activity in other biological fluids, e.g., broncho-alveolar and cerebrospinal fluids, in the search of a locoregional dissemination or dis-simulation of the disease. Decreased SACE has been reported in vascular pathologies involving an endothelial abnormality, e.g., deep vein thrombosis, and in endothelium dysfunctions related to the toxicity of chemo- and radiotherapy used in cancers, leukemias, and hematopoietic or organ transplantations. SACE is also of interest for monitoring arterial hypertension treated with specific synthetic ACE inhibitors. These various reasons for determining ACE activity have led to the development of numerous methods. The most widely used is the spectrophotometric assay using hippuryl-histidyl-leucine as substrate. Fluorimetric and radiochemical assays using both classic and novel substrates have been proposed, but they are time consuming, require special apparatus, and are not suited to automation. Kinetic spectrophotometry of furylacryloyl-phenylalanyl-glycyl-glycine hydrolysis is now used extensively because it is easy to automatize. Efforts are now required to standardize one or more of these assays. Indeed, "normal" plasma values differ not only according to the substrate, but also to the method of determination and to sex and age.