The Significance of Hepatobiliary Enzymes for Differentiating Liver and Bone Diseases: A Case Control Study from Manipal Teaching Hospital of Pokhara Valley

Abstract

Background: Serum alkaline phosphatase (ALP) is a member of a family of zinc metalloprotein enzymes and is secreted mainly by the liver, bone, mucosal epithelia of small intestine, proximal convoluted tubule of kidney and placenta. High mitochondrial aspartate transaminase (AST) is seen in extensive tissue necrosis during myocardial infarction and also in chronic liver diseases like liver tissue deterioration and necrosis. Marked elevations of alanine transaminase (ALT) levels are observed with diseases that involve primarily hepatocytes such as viral hepatitis, ischemic liver injury (shock liver) and toxin-induced liver damage. Serum gamma –glutamyl transferase (?-GT) activity is mainly attributed to the hepatobiliary system and most commonly raised in alcoholic liver disease. The objective of this study is to diagnose hepotobiliary and bone diseases with the facilitation of various biochemical markers as single enzyme lacks the specificity.

Materials and methods: It was a hospital based case control study carried out in the Department of Biochemistry of Manipal Teaching Hospital, Pokhara, Nepal between 1st January 2010 and 31st July, 2011. The variables collected were age, gender, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma–glutamyl transferase (?-GT). The One way ANOVA was used to examine the statistical significant difference between groups. Post Hoc test LSD used for the comparison of means of control versus case groups. A p-value of <0.05 (two-tailed) was used to establish statistical significance.

Results: Of 1500 subjects enrolled in our study, 1200 were cases and 300 were controls. Cases were of viral hepatitis, extrahepatic cholestasis, Paget's disease and osteomalacia. The values of AST and ALT were markedly raised in cases of viral hepatitis when compared to controls, Paget's disease and osteomalacia (p=0.0001). ALP was raised in cases of Paget's disease 1434.8±219.5 (CI 1409.8, 1459.8), extrahepatic cholestasis 907.6±282.8 (CI 875.5, 939.7), osteomalacia 511.8±198.9 (CI 489.2, 534.4) (p=0.0001). ?-GT values was found to be significantly raised in cases of extrahepatic cholestasis when compared to controls (p=0.0001).

Conclusion: It is not easy for clinicians to differentiate and diagnose liver and bone diseases correctly with a single hepatobiliary enzyme. Correlation of variation in several biochemical markers increases the sensitivity and specificity for segregate and identification of liver and bone diseases for proper treatment and prognosis.

DOI: http://dx.doi.org/10.3126/nje.v1i5.6153

Nepal Journal of Epidemiology 2011;1 (5):153-59