| Abstract: |
Cholestasis is not a disease; rather, it is a symptom of many diseases. It is defined as a pathologic state of reduced bile formation or flow. This definition applies more to the experimental situation, where the rates of bile formation and flow can be measured, than to human cholestasis, where neither can be assessed. Therefore, the clinical definition of cholestasis is any condition in which substances normally excreted into bile are retained. The serum concentrations of conjugated bilirubin and bile salts are the most commonly measured ( Moyer, Freese, Whitington et al: 2004) .Neonatal cholestasis is caused by impaired excretion of biliary substances resulting in their accumulation in blood. Neonatal cholestasis should be ruled out in infants presenting with jaundice that persists after 2 weeks of life (Karpen; 2002) .Most cholestatic condition can be classified as anatomic e.g biliary atresia (Haber, Russo;2003) and idiopathic neonatal hepatitis (Roberts ;2003) metabolic e.g tyrosinemia,Niemann - pick disease, galactosemia andα1-antitrypsin deficiency. infections e.g viral hepatitis. toxic e.g parental nutrition-related genetic e.g trisomy 18 and miscellaneous e.g histiocytosis x( Carrell, Lomas; 2002) .The mechanisms of cholestasis can be broadly classified into hepatocellular, where an impairment of bile formation occurs, and obstructive, where impedance to bile flow occurs after it is formed. The typical histopathologic features of hepatocellular cholestasis include the presence of bile within hepatocytes and canalicular spaces, in association with generalized cholate injury. Typical of obstructive cholestasis is bile plugging of the interlobular bile ducts, portal expansion, and bile duct proliferation in association with centrilobular cholate injury ( Oude Elferink RP, Paulusma CC, Groen AK: 2006) .The most important initial investigation is fractionated serum bilirubin levels. Serum transaminases, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), Alkaline phosphatase - Glutamyl transpeptidase (GGT) and Radiological ; abdominal ultrasound, hepatobiliary scintigraphy, magnetic resonance cholangiography (MRC), endoscopic retrograde cholangiography (ERC), duodenal aspirate analysis and liver biopsy are also important(Norton KI, Glass RB, Kogan D et al:, 2002)Neonatal cholestasis can be effectively controlled in most cases by drug therapy such as Choleretic agents : Ursodeoxycholic acid acts to increase bile formation and antagonizes the effect of hydrophobic bile acids on biological membranes , Barbiturates are used to induce hepatic enzyme metabolism in order to decrease serum bilirubin levels in some patients with cholestasis in order to improve function.Vitamins -- Fat-soluble vitamins A, D, E, and K must be administered as individual supplements to assure proper absorption. Bile salt resins -- Bile acid–binding resins form a nonabsorbable complex with bile acids in the intestine, which inhibits enterohepatic reuptake of intestinal bile salts and thereby increases the fecal losses of biles . Antibiotics -- Antitubercular agents induce liver enzymes and ameliorate pruritus secondary to cholestasis (Bu LN, Chen HL, Chang CJ et al: 2003).
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