Bilirubin Direct

Category:

Bilirubin, Direct

Description

Alternative Name : Conjugated bilirubin.

Bilirubin is a dark yellow substance included in the bile and the blood.

Red blood cells (RBCs) normally degrade after 120 days in the circulation. Then, a component of the RBCs called hemoglobin breaks down into unconjugated bilirubin.

Unconjugated bilirubin is transported to the liver, sugars are added to it, so it becomes water soluble, producig conjugated bilirubin.

Conjugated bilirubin pass to the bile and then to the intestines, where a bacteria degrades it.   Furtherwards it is excreted in the feces given them its brown color.

Bilirubin is found then in two variants:

·        Indirect (or unconjugated) bilirubin. Insoluble in water.  It travels through the bloodstream to the liver, where it is converted into direct or conjugated bilirubin.

·        Direct (or conjugated) bilirubin. Soluble in water.

Total and direct bilirubin levels are measured directly in a blood sample.  Indirect bilirubin is calculated from these meassurements.

Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm. In newborns, a blood sample from a heel stick.

Purpose of the test

With high bilirubin levels, the skin and whites of the eyes may appear yellow (jaundice). This must mean liver disease, blood disorders, or blockage of the bile ducts.

Very high bilirubin levels in a newborn can cause brain damage, hearing loss, physical abnormalities, and death.

High bilirubin levels in newborns are not rare, typically 1 to 3 days old. This is called physiologic jaundice of the newborn. After birth, since liver is not very mature, it is unable to process the whole bilirubin, causing the high bilirubin levels

Reference range values

0.0 – 3.4 mcmol/L

Abnormal findings

High levels of Bilirubin in newborns are caused by:

·        Accelerated breakdown of red blood cells due to a blood type incompatibility between the mother and her newborn.

High levels of Bilirubin in adults and children are caused by:

·        Liver damage/disease

·        Gilbert’s, Rotor’s, Dubin-Johnson or Crigler-Najjar syndromes

High levels of unconjugated bilirubin are caused by:

·        Pernicious anemias

·        Transfusion reaction.

High levels of conjugated bilirubin means some kind of blockage of the liver or bile ducts, caused by :

·        Hepatitis

·        Liver trauma

·        Cirrhosis

·        Drug reaction

·        Alcohol abuse