Respective value of alkaline phosphatase, gamma-glutamyl transpeptidase and 5' nucleotidase serum activity in the diagnosis of cholestasis - A prospective study of 80 patients

We studied the value of alkaline phosphatase (AP). gamma-glutamyl transpept idase (GGT), and 5'-nucleotidase (5'-NU) activities in the diagnosis of int rahepatic (GGT) versus extrahepatic cholestasis (EHC). Eighty patients were included prospectively. All presented with cholestasis as defined by a con comitant increase in at least two of three cholestatic enzymes (AP, GGT, 5' -NU), a low cytolytic ratio (alanine aminotransferase/AP [xN/xN] less than or equal to 5), and no evidence for associated liver tumor. We compared 33 patients with THC due to chronic liver disease to 37 patients with EHC due to main bile duct obstruction. Easting blood samples for activity determina tion (AP, GGT, 5'-NU) were taken before performing liver biopsy in cases of IHC and before endoscopic or surgical management in cases of EHC. Enzyme a ctivities were compared using univariate and multivariate analysis. AP (276 IU/L [35-3140] vs. 123 IU/L [37-699]; p < 0.0001), GGT (595 IU/L [98-5200] vs. 211 IU/L [38-925];p < 0.0001), and 5'-NU (32 IU/L [10-142] vs. 16 IU/L [4-107]; p < 0.0003) were significantly higher in EHC when compared to IHC . Only in GGT and 5'-NU activities were independent variables significantly linked to the mechanism of cholestasis. In IHC, the ratio GGT/5'-NU (xN/xN ) was significantly lower than in EHC (2.8 [0.7-7.2] vs. 3.7 [1.8-10.5]; p < 0.006). A threshold of GGT/5'-NU < 1.9 had a sensitivity of 40% and a spe cificity of 100% for the diagnosis of IHC. Although such hepatobiliary enzy mes cannot be regarded as diagnostic, they can provide useful information t o orientate the clinician in the diagnosis of cholestasis.