Читать книгу Manual of Equine Anesthesia and Analgesia - Группа авторов - Страница 51

 Increased TBIL in serum is an indicator of hepatic dysfunction, hemolysis, or reduced feed intake.

 TBIL may be subdivided into unconjugated (indirect) bilirubin, and conjugated (direct) bilirubin.

 The reference range for the horse is 21–57 μmol/l for TBIL; 2–10 μmol/l for conjugated bilirubin, and 18–52 μmol/l for unconjugated bilirubin.

 Hepatic dysfunction causes both indirect and direct concentrations to rise.If direct is greater than 8% of total, liver disease should be suspected as a contributor to the increase.

 Biliary obstruction (e.g. cholelithiasis) increases the direct to indirect ratio.

 Hemolysis raises the serum indirect concentration.

 Reduced feed intake raises the serum indirect concentration as a result of slowed clearance of bilirubin from the blood rather than from its overproduction. However, the cause is uncertain.Ligandin, a protein responsible for bilirubin uptake into the liver may be decreased in the fasting horse, as has been demonstrated in rats.Free fatty acids may play a role in fasting hyperbilirubinemia, and horses develop significant hyperlipidemia during fasting. This may result in competition for carrier proteins.Increases in unconjugated bilirubin occur after 12 hours of fasting.

 Neonates have higher bilirubin values due to immaturity of liver processing.This can lead to kernicterus, resulting from unconjugated bilirubin causing neurologic damage. However, this condition is extremely rare in foals, and may be more likely to occur in a foal with neonatal isoerythrolysis.