Hyperbilirubinemia

Following are differential diagnoses for patients presented for hyperbilirubinemia.

Prehepatic Causes (Hemolysis) 

• Idiopathic (primary) immune-mediated hemolytic anemia 

• Secondary immune-mediated hemolytic anemia 

  • Infectious disease 

  • Drug- or vaccine-induced  

  • Paraneoplastic 

• Nonimmune hemolysis  

  • Toxin (eg, zinc, onion) 

  • Erythrocyte fragmentation/microangiopathic anemia (caval syndrome, disseminated intravascular coagulation [DIC], vasculitis)  

  • Envenomation  

  • Metabolic (hypophosphatemia)  

  • Alloimmune (blood transfusion, neonatal isoerythrolysis [cats]) 

  • Breed-specific erythrocyte membrane or enzyme defects (eg, increased osmotic fragility [Somali, Abyssinian, and Siamese cats], stomatocytosis [Alaskan malamute, Drentsche Patrijshond, and miniature schnauzer], phosphofructokinase deficiency [English springer spaniel, Abyssinian, and Somali cat])  

Hepatic Causes (eg, Hepatocellular Dysfunction, Cholestasis)

• Toxic or drug hepatopathy 

• Inflammatory or infectious hepatopathy (eg, immune-mediated or infectious hepatitis, cholangiohepatitis, leptospirosis, cytauxzoonosis [cats], FIP)  

• Hepatic lipidosis (cats) 

• Neoplasia   

• Fibrosis

Posthepatic Causes (eg, Cholestasis, Defective Biliary Excretion)

• Biliary  

  • Gallbladder mucocele 

  • Cholelithiasis 

  • Stricture 

  • Infectious or inflammatory cholecystitis/cholangitis 

  • Neoplasia (gallbladder, bile duct) 

• Extrabiliary 

  • Pancreatitis 

  • Neoplasia (pancreas, duodenum, regional lymph nodes) 

  • Proximal duodenal obstruction (eg, mass or foreign body causing secondary bile duct obstruction) 

  • Bile peritonitis (ie, gallbladder or common bile duct rupture)   

  • Septicemia (eg, cytokine-mediated cholestasis, downregulation of bilirubin transport receptors)  

Other Causes

• Spurious (eg, artifact due to lipemia or hemolysis)