What is bilirubin?
Bilirubin is the component of the bile, and is produced in large part by the degradation of hemoglobin, following the destruction of red blood cells in the body. Red blood cells contain hemoglobin which is broken down to heme and globin. Heme is converted to bilirubin, which is then carried by albumin in the blood to the liver. In the liver, most of the bilirubin is chemically attached to another molecule before it is released in the bile. This attached bilirubin is called direct bilirubin. Bilirubin which is not attached to another molecule before its release in the bile is called indirect bilirubin. Total serum bilirubin equals direct bilirubin plus indirect bilirubin.
Bilirubin is a yellow to orange bile pigment, and it normally circulates in the plasma, and is taken up by the liver cells and conjugated to form bilirubin diglucuronide, which is the water-soluble pigment excreted in the bile. Failure of the liver cells to excrete bile, or obstruction of the bile ducts can lead to an increased amount of bilirubin in the body fluids and henceforth to obstructive jaundice. Jaundice is the yellow color in the skin, mucus membranes, or the eyes. Jaundice is the most common reason to check a patients bilirubin levels, and this test is most common when there is a newborn baby, as most newborns have some jaundice, or when the jaundice develops in older infants, children and even adults. The bilirubin test is also conducted when the patient might be suspect that they have liver or gallbladder problems.
Why measure the level of bilirubin?
Bilirubin is an indicator of the health of the liver and may be useful for evaluating the presence of biliary obstruction, hepatitis, cirrhosis, jaundice. If there is an increase in the direct bilirubin in the blood, then this is a direct indication for liver damage, while an increase in indirect bilirubin may suggest a change in the cycle of degradation of hemoglobin.
The test can be executed in two ways, it can either measure out the total bilirubin present or the fractional bilirubin present (or direct bilirubin). It is normal for bilirubin to be present in the blood. Normal direct or conjugated bilirubin levels range from 0 to 0.3mg/dL, while the normal levels of total bilirubin range from 0.3 to 1.9 mg/dL.
Standard of preparation
Sampling is usually done in the morning in the hospital. There are no special preparations needed for this test. The doctor will advise and recommend if you need to be fasting prior to the blood examination. You should inform your doctor of any medication you are taking prior to the exam, as some medical treatments may interfere with the blood results.
Is the examination painful or dangerous?
The examination is neither painful nor dangerous. The patient may feel a tingling sensation with the entrance of the needle in the arm when blood is being extracted for examination.
How is the exam performed?
The exam consists of a simple blood sample test.