|What is the purpose of this test:
Total bilirubin and conjugated bilirubin (direct) is measured to diagnose and monitor hepatobiliary disorders.
|How to prepare:
- A simple blood sample is taken.
- Dietary restrictions are not necessary.
Newborns have higher levels of bilirubin, especially when they are premature.
- Total bilirubin: < 17="">
- Conjugated bilirubin: 0 to 3.4 mcmol/L
In most cases, conjugated hyperbilirubinemia is associated with abnormal liver function. A semi-quantitative measurement of bilirubinuria (presence of bilirubin in urine) is used to highlight conjugated hyperbilirubinemia and to closely monitor related disorders.
Bilirubin is the breakdown product of red blood cells and other blood proteins. Unconjugated bilirubin, which is not soluble in water, travels in the bloodstream, bound to albumin, and is transported to the hepatocytes (liver cells). It is then transformed so it can be conjugated to glucunoric acid and become soluble in water. Conjugated bilirubin is then excreted in the bile ducts and makes its way into the small intestine. Part of the bilirubin is eliminated in feces while the rest is reabsorbed by the intestine.
The measurement of unconjugated bilirubin is done indirectly by calculating the difference between the amount of total bilirubin and conjugated bilirubin (direct).
What does an abnormal test result mean?
If test results are high
- Unconjugated bilirubin:
Excessive unconjugated bilirubin levels may result from the breakdown of red blood cells, ineffective erythropoiesis (premature death of red blood cells), reabsorption of a large hematoma, neonatal jaundice, Crigler-Najjar syndrome (enzyme deficiency that results in impaired conjugation of bilirubin) or Gilbert's syndrome.
- Conjugated bilirubin:
A rise in conjugated bilirubin is indicated by the presence of cholestasis (impaired bile secretion) and other hepatocellular disorders including: hepatitis (alcoholic, viral, auto-immune), cirrhosis, hemochromatosis (iron overload), Wilson's disease (copper accumulation), etc.
Factors that can affect results
- Certain drugs, hemolyzed samples and lipemia can contribute to producing false results.
Some drugs may increase bilirubin levels in the blood. Here are a few examples:
- Acetaminophen (Tylenol®)
- Mesalamine (Asacol®)
- Chlorpromazine (Largactil®)
- Aldesleukin (Proleukin®)
- Methyldopa (Aldomet®)
- Propylthiouracil (Propyl thyracil®)
- Sulfasalazine (Salazopyrin®)
- Oral contraceptives
What you should know before going for this
Before going for a blood test, examination or other, it is always a good idea for you to have a complete list of all prescription and over the counter medications and/or natural products you may be taking. If you are unsure or have any questions, your pharmacist will be able provide you with additional information.