The measurement of serum or plasma bilirubin is usually performed to investigate the causes of liver disease and jaundice, and to monitor a patient’s progress, e.g. an infant with serious neonatal jaundice (high levels of unconjugated bilirubin).
Bilirubin is a product of erythrocytes breakdown and exists as conjugated or non- conjugated. These two combined gives the Total Bilirubin.
What are normal ranges for Total bilirubin?
Adults: 3–21 mol/l 0.2–1.3 mg/100 ml
Newborns: 8–67 mol/l 0.5–4.0 mg/100 ml
What does high serum Bilirubin indicate?
RISE in the level of bilirubin in the blood is called hyperbilirubinaemia. The main causes are as follows:
● Overproduction of bilirubin caused by an excessive breakdown of red cells (haemolytic jaundice). The bilirubin is of the unconjugated type.
In tropical countries haemolysis is due mainly to:
– Severe falciparum malaria.
– Sickle cell disease haemolytic crisis.
– Haemolysis associated with glucose-6-
phosphate dehydrogenase deficiency and
hereditary spherocytosis.
– Antigen antibody reactions as in haemolytic disease of the newborn, autoimmune haemolytic anaemias, or following an incompatible blood transfusion.
– Toxins from bacteria, snake venoms, drugs or herbs.
● Liver cell damage in which there is usually an increase in both conjugated and unconjugated bilirubin (hepatocellular jaundice). The commonest causes are:
– Hepatitis caused by hepatitis viruses and other viruses
– Leptospirosis
– Relapsing fever
– Brucellosis
– Typhoid
– Chemicals, plant toxins and drugs
● Metabolic disturbances in the liver involving defective conjugation, transport and, or, excretion
of bilirubin. Examples include:
– type of neonatal jaundice, often referred to as ‘ physiological jaundice’
– Rare inherited disorders of conjugation such as Gilbert’s and Crigler-Najjar syndromes.
● Partial or complete stoppage of the flow of bile through bile channels with a build up of conjugated bilirubin in the blood (obstructive
jaundice). Cholestasis can be due to:
– Obstruction of the extra-hepatic biliary ducts by gallstones, tumours (especially hepatomas and carcinoma of the pancreas), cholangitis
(inflammation of the biliary ducts), or by
helminths such as Opisthorchis and Fasciola species. Occasionally heavy Ascaris infections, especially in children, may result in blockage of the common bile duct.
– Pressure on the small bile ducts as may occur in hepatitis or as a side effect of drugs.
NB: Mild to moderate hyperbilirubinaemia may also be found in association with any serious condition such as a terminal illness, or following major trauma, surgery, or blood transfusion
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