Known by many, understood by few. Here we explain what Bilirubin is.
In this article we will see what bilirubin is and why it sometimes rises (As a small advance, we make it clear that it does not have much to do with looking and not being looked at).
What is Bilirubin?
Bilirubin is a protein found naturally in the blood, the result of the natural degradation of hemoglobin. Unlike hemoglobin, which gives blood a red color, bilirubin gives tissues a yellowish color, which is evident when we look at old bruises, which turn from a purplish color to yellow-green.
Normally, we produce about 4mg of bilirubin for every kilo/day. About 80% of this bilirubin is the result of the natural metabolism of red blood cells, whose half-life is about 100 or 120 days, and when degraded they release their hemoglobin, which will be metabolized by the body to facilitate its excretion through a process called glucuronidation, thus giving rise to bilirubin.
Bilirubin is very easily dispersed throughout the body, so its conjugation with other molecules is necessary for its correct processing. We will then find direct bilirubin, also called conjugated bilirubin, which binds in the liver to glucuronic acid for excretion through the gallbladder, where it will pass to the gastrointestinal tract to leave the body in the urine and feces.
Indirect, or unconjugated, bilirubin can bind to blood serum proteins such as albumin, although it can also be found unconjugated with any protein. This form of bilirubin is more harmful to the body, since it is capable of crossing even the blood-brain barrier, and can cause damage to the brain.
This molecule is also responsible for the coloration of feces and urine , although very high levels of bilirubin (greater than 3mg per deciliter of blood) cause a yellowish coloration of the skin and the whites of the eyes, called jaundice.
Why does it go up?
Diseases such as hemolytic anemias, which lower the half-life of red blood cells, can trigger a rise in bilirubin. The rise in bilirubin and jaundice are closely related to liver diseases, since a malfunction of the liver causes an accumulation of free bilirubin, as it cannot process the bilirubin that the body generates so easily due to liver damage.
There are also rare genetic diseases, such as Gilbert or Crigler-Najjar syndrome , whose patients suffer from deficiencies in enzymes necessary for the natural processing of bilirubin by glucuronidation.
The most common causes of increased bilirubin in adults are gallstones , which obstruct the bile duct preventing the excretion of bilirubin, liver or bile duct inflammation, or cholestatic processes, common especially in pregnant women, where the normal bile flow is impaired.
In neonates, on the other hand, jaundice is quite common, around 60%, reaching incidences of 80% in premature babies born before 37 weeks of pregnancy. This is because neonates have a high rate of red blood cell production and destruction, while their liver is small and underdeveloped, so it is not able to process all the bilirubin that is continually being generated.
Neonatal jaundice usually resolves in less than two weeks without the need for medical intervention , but in cases where the bilirubin reaches levels that are too high, it is necessary to treat it with blood transfusions or phototherapy, since the brain damage it causes bilirubin (called kernicterus or kernicterus) can leave permanent sequelae.
Diagnosis
Jaundice itself is easily identifiable , but its causes are varied and require diagnostic tests to determine the cause of the increased bilirubin.
To this end, the causes can be separated into three categories that allow expediting the diagnosis.
1. Prehepatic Causes
They happen before bilirubin conjugates with glucuronic acid and reaches the liver . They are easily identifiable by the lack of increased values of bilirubin in the urine and may show an enlarged spleen. These are usually the result of anemia or the reabsorption of hematomas.
2. Hepatic Causes
They correspond to liver dysfunction, for example due to cirrhosis or liver cancer . They are identifiable by hepatic inflammation, an increase in proteins that indicate liver damage, and the presence of bilirubin in the urine. In cases of hepatitis, it is possible to do genetic tests to determine if it is of viral or bacterial origin. Genetic tests would also allow us to rule out diseases such as Gilbert’s Syndrome, which has a genetic component.
3. Posthepatic Causes
They are those that happen after the bilirubin leaves the liver , usually caused by obstructions of the bile duct, most of them stones in the gallbladder. In these cases, a surgical intervention may be the only way to improve the affected person’s condition.
Treatment
The treatment of jaundice as such in adults is not always necessary , such as when we talk about disorders such as Gilbert’s syndrome, but it can be the treatment of the causative agent of the disease. Gallstones may require surgery for the patient to improve and in those cases in which there is liver damage due to substance abuse, it will be necessary to stop exposure to the cause so that improvement can occur.
Even so, for cases that do not require treatment, we can speed up the passage of bilirubin (and the yellow color it carries) through our body by avoiding alcohol, red meat, and taking laxatives as needed.
- It may interest you: How to stop diarrhea? 12 very effective natural remedies
Bibliographic references
- Mosqueda, L. (2005) The life cycle of bruises in older adults. Journal of American Geriatrics.
- Braunstein, Evan (2019) Overview of Hemolytic anemia.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.