Bilirubin is a substance produced by the liver after breakdown of dead and unused red blood cells by the body. It mixes with bile and passes into the digestive system. A small percentage of bilirubin gets re-absorbed while the rest is excreted from the body. Brown color of stool is due to presence of bilirubin in it.
Excess bilirubin levels are typically indicative of underlying jaundice. It often occurs in people with liver problems. Low bilirubin level is uncommon and may occur due to excessive caffeine intake; side effects of certain drugs; and elevated vitamin C levels, etc.
Normal Bilirubin Values
Presented below is a table of normal bilirubin values. It can differ from one lab to another. The values mentioned in the lab report are evaluated by doctors as per the health of the patient and other related factors.
| Bilirubin type | Bilirubin level |
| Total bilirubin | 0.0-1.4 mg/dL or 1.7-20.5 mcmol/L
|
| Direct bilirubin | 0.0-0.3 mg/dL or 1.7-5.1 mcmol/L
|
| Indirect bilirubin | 0.2-1.2 mg/dL or 3.4-20.5 mcmol/L
|
Low Bilirubin: Symptoms and Associations
Low bilirubin levels do not result in any direct symptoms. The signs and symptoms that are visible typically occur as part of some underlying causative condition.
Studies have shown that bilirubin has anti-inflammatory and anti-oxidant properties and is not just a by-product of blood.
- Research shows that low bilirubin may have a role in lung cancer in people who smoke. This proves the effect of normal levels of bilirubin as an anti-oxidant.
- Studies have shown the relationship between low bilirubin levels and angina. Angina occurs due to blood vessels inflammation, coronary artery disease, and/or arteriosclerosis. This is evidence that normal levels of bilirubin prevent inflammation.
- Studies suggest that normal bilirubin levels may play a role in protection of body cells from death or injury
- New research suggests of a possible link between End-Stage Kidney Disease and low bilirubin levels. It has been found that people undergoing dialysis or those who have already undergone dialysis tend to have low bilirubin.
Causes of Low Bilirubin
Low bilirubin in healthy individuals may occur due to following causes:
- Excessive intake of caffeine. Xanthines which decrease bilirubin levels are present in caffeine.
- Increased intake of vitamin C. Some doctors suggest intake of vitamin C supplements as treatment for high levels of bilirubin
- Use of theophylline, a medicine for lung disease; it has xanthines which decreases bilirubin
- Use of seizure medication Phenobarbital. It decreases the levels of bilirubin.
- It is postulated that conditions like seasonal depression, coronary artery disease, End-Stage Kidney Disease, and hemolytic anemia may cause low bilirubin levels.
Bilirubin testing
There are two kinds of bilirubin that occur in the bloodstream, as mentioned below:
- Indirect/Unconjugated Bilirubin: This type of bilirubin passes via blood into the liver. The liver then processes it into direct bilirubin.
- Direct/Conjugated Bilirubin: This form of bilirubin is tested by different blood measurements. The liver uses indirect bilirubin and mixes it with sugars so that it becomes water soluble. It is then released into the colon so that it can be eliminated from the body.
Lab tests are normally done for direct bilirubin. However, indirect bilirubin can be calculated by subtracting direct bilirubin from the total bilirubin (which can be found via lab tests)
Treatment of Low Bilirubin levels
Low bilirubin levels do not require any medical treatment in healthy people as it does not cause any medical complications. Doctors may however monitor and keep an eye out for low bilirubin in people with kidney problems.
People may follow the steps listed below to keep bilirubin levels to normal if they are low:
- Take vitamin C only up to the recommended levels per day
- Decrease the intake of caffeine
- Stop smoking and thus lower the risk to lung cancer
It is important to always consult a doctor in order to raise low bilirubin levels.
High bilirubin
High bilirubin can cause different medical health problems like jaundice, damage to red blood cells, and brain damage, etc. It is important to seek immediate medical attention for treatment of high bilirubin levels.
High bilirubin may be caused due to the following reasons:
- Underlying illnesses that cause damage to liver; these include cirrhosis, hepatitis, mononucleosis, etc.
- Certain infections like cholecystitis and/or infected gallbladder, etc.
- Conditions marked by bile ducts obstruction or blockage; these include pancreatic cancer, gallstones, etc.
- Hereditary diseases like Gilbert’s syndrome which adversely affects the manner in which bilirubin is processed by the liver.
- Intake of medications that elevate bilirubin levels; these include certain contraceptives, several antibiotics, flurazepam, Valium/diazepam, Dilantin/phenytoin, and Indocin/indomethacin
- Fast destruction of RBCs present in blood; it can occur due to underlying sickle cell disease or due to transfusion reaction, i.e., allergic reaction/response to blood injected during a transfusion.
