The bilirubin test is a laboratory assay that calculates the amount of bilirubin present in the bloodstream. Bilirubin is a yellow-coloured liquid substance that is formed during the breakdown of the iron component i.e. heme, of haemoglobin in the blood. It is essentially a waste product that is subsequently passed on to the liver for elimination from the body.

The Liver And Its Functions:

The liver is a vital internal organ in humans, roughly bearing the shape of a half-moon and situated in the upper portion of the abdomen, towards the right side of the body, beneath the rib cage. It performs various key functions including the production of crucial proteins, detoxification of circulating biochemicals, as well as the synthesis of requisite substances for smooth digestion and optimal growth of cells, tissues within the system. The liver also processes medications and drugs that are ingested for resolving other health anomalies, into simpler, non-toxic chemical substances, thereby making it easier and safer to absorb by the other cells and tissues.
Bilirubin test

One key task carried out by the liver is the production of bile, a fluid substance that aids in breakdown of fats into fatty acids for unimpeded digestive functions within the small intestine. It also assists in the synthesis of proteins that compose blood plasma, as well as cholesterol and particular proteins to transport fats across the system. The biochemical conversion of surplus glucose in the body to glycogen also takes place in the liver and in times of energy requirements, these glycogen stores can be utilised to make glucose and preserve energy balance. It controls the concentrations of amino acids in blood, crucial for healthy protein synthesis and maintains optimal iron levels by eliminating the surfeit through bilirubin.

It is thus very important to monitor the liver routinely for people of all age groups and also critical to test for liver illnesses such as jaundice, hepatitis, as soon as discomforting symptoms are reported. Both, assessing the health status as well as diagnosing diseases can be done by means of the bilirubin test, as well as other diagnostic assays that are usually performed concurrently with it. These include liver function tests to probe the amounts of hepatic enzymes or proteins in blood, albumin and total protein test, complete blood count and prothrombin time i.e. the time taken for clotting of plasma in the system. Read on, to understand the salient details regarding the bilirubin test.

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The Bilirubin Test:

Although bilirubin is merely a by-product, formed solely to excrete surplus heme and prevent the metallic iron compound from accumulating within the system, it serves as a pivotal marker to detect liver functions. For only when the hepatic tissues are operating properly will bilirubin levels remain in the normal range. When high bilirubin levels are observed, it usually indicates jaundice, hepatitis, obstruction in bile ducts or other disorders in the liver.

How It Is Done:

In a diagnostic medical setting, the bilirubin test is carried out by collecting a sample of blood from the patient. For young adults and elderly, blood is extracted from the turn in the arm, using a tiny sterile needle inserted into a vein in the region. The other end of the needle holds a small tube with which the pure blood sample is collected without any external contamination or direct contact. This blood sample is then sent to medical experts at the laboratory for in-depth scrutiny.

There are no grave complications arising from the bilirubin test. Only mild pain is experienced in the area of piercing the needle and a very minor puncture mark or wound scar is formed in that specific vicinity. There is no necessity to rest after giving blood samples for a bilirubin test as the amount of blood collected is only normal and not vast, thereby causing no fatigue and enabling the patient to proceed with normal tasks at home and work.

Why It Is Done:

Bilirubin test is performed to evaluate the liver functions in various settings of health and disease. It is carried out to observe the efficacy of a specific medical treatment being given to the patient, detect drug toxicity within the body and look for signs of anemia caused by damage to healthy red blood cells and lack of sufficient iron in the system.

Also Read: Anemia: Causes, Symptoms And Treatment

Primarily bilirubin test is carried out in patients who display obvious external symptoms of liver ailments such as jaundice, where the skin and eyes become yellow in colour, bile duct blockages and defects in the liver or gall bladder and inflammation in the liver i.e. hepatitis.

Possible Outcomes:

The lab reports mention bilirubin levels as direct, indirect and total bilirubin, wherein total bilirubin is the sum of direct and indirect values and these numbers imply varying outcomes, based on the results. Usually, the numbers are mentioned for direct bilirubin and total bilirubin.

While the normal values for direct bilirubin for all adults are 0.3 milligrams per deciliter (mg/dL), the total bilirubin numbers are 1.2 mg/dL for adults and 1 mg/dL for those below the age of 18 years.

Sometimes, the higher intake of some food groups, routine ingestion of potent medications and arduous workouts and exercising can be the reason why bilirubin levels are slightly different form the normal values in adults. It is hence advised for patients to mention all of these factors to the doctor prior to assessing the outcomes of their bilirubin test.

Usually, bilirubin levels lower than the normal numbers are not any cause for concern and do not indicate any grave health condition. Higher than normal bilirubin levels mean that the liver is unable to get rid of bilirubin carrying the excess iron efficiently, signifying liver damage, hepatitis, jaundice, cirrhosis, fatty liver or other less common hepatic ailments. However, the bilirubin test is not confirmative for these liver diseases and additional tests are recommended to be taken by the healthcare provider, to conclusively diagnose the exact liver disorder in the patient.


Bilirubin is a substance synthesized when the liver breaks down the iron component in blood i.e. heme in hemoglobin. Hence the bilirubin test is a useful diagnostic assay to detect a host of liver conditions like jaundice, hepatitis etc. and also gauge the healthy operations of the liver, a key internal organ for detoxification of the body, in healthy individuals and those patients undergoing treatment procedures for other conditions.