Bilirubin Test: Direct vs Indirect, Normal Range Values

A healthy liver plays a very important role in the maintaining the overall health of an individual. One of the quickest indicators of a damaged liver is bilirubin coloration of stool and urine.
Bilirubin is a yellow coloured substance found in fluid present in liver known as bile. It is produced in bone marrow cells and also produced due to breakage of red blood cells. Role of bile is to help in digestion of food. Your liver takes bilirubin from your blood and carries out changes in its chemical make-up and it is passed through your faeces as bile, giving yellow colour to your stool.

What is bilirubin test and what are the normal levels?

A bilirubin test is used for the purpose of measuring the amount of bilirubin (unconjugated and conjugated bilirubin) in a person. It is a important parameter to find the cause of several health issues such as anaemia,etc.
Blood, amniotic fluid and urine are tested to check the levels of bilirubin in a patient. Higher levels of bilirubin levels indicate the unusual breaking down of red blood cells (haemolysis) or improper functioning of liver etc.
Normal levels of bilirubin range from about 0.2 – 1.2 mg/dL. When liver gets damaged, bilirubin leaks out in the blood, and it leads to severe health issues. Sometimes, it is secreted out through urine and darkens the colour of urine. 

Difference between Direct and Indirect Bilirubin

Direct bilirubin is modified indirect bilirubin. The covalent modification of indirect bilirubin is carried out to decrease the toxicity of bilirubin and to enhance its solubility. Elevating its solubility makes excretion of bilirubin quite easier. Unconjugated or indirect bilirubin is an immediate breakdown product of haemoglobin. It is soluble in lipids and is known as lipophilic. It is not soluble in water, thus it is hydrophobic. It is known to cross the plasma membrane easily.

What does Bili total mean?

This blood test evaluates the amount of a substance called bilirubin. This test is used to find out the efficacy of liver function. It is often a part of panel of tests that are required to measure liver function. A small amount of bilirubin in your blood is normal, but a high level is an indication of a liver disease.

Who should get the test and who should not?

Your doctor may ask you to go for bilirubin test if you have anaemia, jaundice, toxic reaction to drugs and cirrhosis etc. If you are presentig with symptoms such as nausea, vomiting, dark urine, fatigue etc., you may have imbalance in levels of bilirubin (webmd, 2021).

What happens after a bilirubin blood test?

If your blood test indicates the elevated levels of bilirubin, doctor may ask for further tests in order to diagnose the underlying cause. Once the cause of high bilirubin level is determined, you may have to undergo more tests to track the efficacy and prognosis of treatment. If your doctor thinks that there may be some issues related to your liver or gallbladder, he may ask you to have imaging tests to rule out abnormalities related to the structure or position of the same.

Understanding the Low and High bilirubin levels 

Low bilirubin levels are sometimes associated with the intake of certain medications such as phenobarbital, theophylline etc. High bilirubin levels in adults is an indication of several health issues such as unusual breakdown of red blood cells, scarring and inflammation of liver, gallstones, pancreas or gallbladder cancer etc.

• Elevated bilirubin levels in new born babies are detected by the presence of skin jaundice, seizures, drowsiness, anaemia etc. Factors behind new-born jaundice are birth trauma, maternal drug intake, liver infection etc. Photo therapy, transfusions and intravenous immunoglobulin is helpful in the treatment of high levels of bilirubin in newborn babies. Generally, a paediatrician looks after the management of bilirubin levels in neonates.
• Generally, adults with increased bilirubin levels are  asked to avoid alcohol and compounds causing liver-stress. Healthcare professionals play a crucial role in determining what one should do to manage bilirubin levels as per the root cause of the issue.

What is a dangerous level of bilirubin in adults?

Bilirubin level of 5% is generally considered as dangerous level and it needs to be evaluated in a proper manner in order to know the underlying cause. A small amount of blood is withdrawn from vein in patient’s arm, and this blood is stored in a tube. In neonates, blood is drawn by utilization of a needle in order to break heel’s skin.

How long does it take to get the results of a Bilirubin test?

It usually takes 1-2 hours to get the results of a Bilirubin test.

What is the cost of Bilirubin test in India?

The cost of a Bilirubin test in India varies between diagnostic centres. With Redcliffe Labs the Bilirubin Total test cost is just Rs 139.

Conclusion

Higher levels of bilirubin levels indicate the unusual breaking down of red blood cells (haemolysis) or improper functioning of liver etc. It is to be concluded that in order to carry out Bilirubin test, patients are asked to fast for several hours before undergoing the test. They are advised not to do strenuous workout as it generally elevates levels of bilirubin. Other than this, drugs like caffeine, salicylates and penicillin should not be taken before the test as they may decrease bilirubin levels.