The human body is a balancing act, continually fuelling and cleansing itself via a myriad of systems. The liver helps filter waste products from the body but requires help from special enzymes, acids, and gasses to perform its duties. Bilirubin, a component in blood, can cause jaundice in newborn babies because their small bodies cannot filter out enough of the waste-byproduct. Other issues with medications and illnesses cause high and low levels of bilirubin, which can develop into disease.
Bilirubin is a reddish-yellow compound in bile. The liver produces it for a variety of purposes that keep the human body healthy. Bilirubin is responsible for the characteristic yellow color of the skin and the whites of the eyes of people with jaundice. It also causes the yellowish tint common to healing bruises.
Bile plays a critical role in the breakdown of fats in the body, helping the small intestine absorb the fat consumed through diet. The compound forms in the liver and is comprised of cholesterol, lecithin, pigments, salts, and, of course, bilirubin (once it is conjugated). It also allows for the absorption of vitamins A, D, and E. The gallbladder stores bile between meals.
The breakdown of heme (a critical component of hemoglobin) in red blood cells produces bilirubin. At first, the bilirubin is unconjugated or indirect. In this state, bilirubin is not water soluble. Albumin binds to it, allowing it to travel through the body to the liver. In the liver, an enzyme (glucuronyltransferase) turns it into conjugated or direct bilirubin, making it soluble in water and able to move into the bile. After the bile has fulfilled its purpose, the body reabsorbs it and any unconjugated bilirubin, while conjugated bilirubin passes into the colon and is turned into urobilin and stercobilin. Urobilin is expelled by the kidneys and gives urine its yellow color. Stercobilin is excreted in the stool, coloring it brown.
The body normally removes bilirubin through the urine and stool, keeping levels in the body reasonably stable. When the body produces too few enzymes, it cannot process all the conjugated bilirubin, so levels of the unconjugated form begin to build up. If the liver is damaged or diseased, this can also impede its ability to process conjugated bilirubin. The weakened organ may not be able to work fast enough to keep up with the body's bilirubin production. Very high levels of unconjugated bilirubin can be dangerous.
Very high levels of the waste product bilirubin can be severe for newborn babies. Unconjugated bilirubin damages developing brain cells, which leads to neurological problems. That said, high levels of unconjugated bilirubin are normal in newborns; approximately 60 percent of babies have jaundice because their bodies can’t remove enough bilirubin so early in life. Kernicterus, critically high bilirubin levels, isn't common, but it is important to treat babies with this condition right away to prevent brain damage.
Typical signs of jaundice such as the skin and whites of the eyes turning a yellowish color are common in newborn babies. However, Kernicterus symptoms are more severe and include lethargy, which means they are unusually sleepy and difficult to wake up. When they do wake up, they often drop right back to sleep. Other symptoms of kernicterus include high-pitched or inconsolable crying, decreased appetite and less feeding than usual, limp or floppy body, unusual eye movements, and seizures.
Light therapy is a standard treatment for newborn babies and exposes the baby to natural or artificial light sources for specified periods of time. The increased exposure to light sources helps the body expel bilirubin by triggering the change to water-solubility and enabling removal of the compound.
Gilbert’s syndrome is a hereditary genetic disorder. Five to ten percent of the population is believed to have Gilbert’s syndrome, which causes lower enzyme activity, making it difficult for the liver to remove bilirubin from the blood. In adults, moderately increased unconjugated bilirubin levels are generally not harmful. People with Gilbert’s syndrome often find specific triggers cause an episode of jaundice, such as dehydration, going without food for extended periods, stress, lack of sleep, and menstruation.
Other causes of high unconjugated bilirubin levels include antipsychotic drug use, chemotherapy, and other medicines that impact the immune system. Built-up waste-products like bilirubin can damage the liver and other tissues of the body. Severely high bilirubin levels can turn into bile duct blockage, cirrhosis, or other liver diseases and conditions.
Laboratory tests are typically necessary to determine if a patient has high levels of unconjugated bilirubin. A blood test called the 'Van Den Bergh Reaction Test' provides data about levels of conjugated and unconjugated bilirubin using the part of the blood called serum. The diluted serum is introduced to a chemical and depending on the reaction, a healthcare professional gauges whether the blood sample has normal or high levels of bilirubin.
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