Dark urine with pale stools in infants under three months

Specialty: Pediatrics.

• Suspected neonatal cholestasis
• pediatric cholestatic jaundice
• acholic stools

Why it occurs

• Extrahepatic bile duct atresia (idiopathic progressive fibrotic obstruction of the extrahepatic biliary tree, considered a pediatric surgical emergency requiring intervention before 60 days of life)
• Chole duct cyst or structural anomalies of the biliary tree (congenital malformations that mechanically obstruct bile flow)
• Neonatal sepsis or urinary tract infection (the release of bacterial endotoxins functionally alters the transport of bile acids in the hepatocyte)
• Idiopathic neonatal hepatitis or cholestasis secondary to prolonged parenteral nutrition (in premature infants due to immaturity of bile transporters)
• Alagille syndrome or other familial intrahepatic cholestasis (multisystem genetic disease due to JAG1 mutation with paucity of intrahepatic bile ducts)
• Alpha-1 antitrypsin deficiency or galactosemia (genetic metabolic disorders that damage the liver parenchyma early)

Initial workup

Serum bilirubin fractionation (total, direct and indirect bilirubin; cholestasis is defined if direct bilirubin is greater than 1 mg/dl or represents more than 20% of total bilirubin). Complete liver profile: ALT, AST, GGT (gamma-glutamyl transferase, typically very elevated in biliary atresia and normal in some intrahepatic cholestasis), alkaline phosphatase, prothrombin time (PT/INR) and albumin. Abdominal ultrasound after a 4-hour fast (to assess the presence of the gallbladder, the "echogenic triangle" sign in the portal bifurcation suggestive of biliary atresia, or rule out common bile duct cysts). Hepatobiliary scintigraphy with Tc99m-IDA after previous stimulation with phenobarbital (absence of excretion of the radiotracer to the intestine at 24 hours supports biliary atresia). Percutaneous liver biopsy for histopathological study (gold standard).

Standard management

• Ursodeoxycholic acid — choleretic hydrophilic bile acid that protects the hepatocyte from accumulated toxic bile acids; dose of 15 to 30 mg/kg/day orally divided into 2 or 3 doses
• Phytomenadione or Vitamin K1 — mandatory immediate treatment to correct coagulopathy due to deficiency in the absorption of fat-soluble vitamins; doses of 1 to 2 mg intravenously or subcutaneously, followed by regular oral supplementation
• Vitamin supplement of fat-soluble vitamins — A, D, E and K in special water-soluble formulation due to the absence of bile salts in the intestinal lumen
• The definitive treatment of biliary atresia is surgical through the Kasai portoenterostomy.