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Tuesday, October 14, 2008

Knowledge about Jaundice !

[Extracted from]

What is jaundice ?

Jaundice is yellowing of the skin, sclera (eyes) and mucous membranes caused by increased levels of bilirubin in the system. Usually the concentration of bilirubin in the blood must exceed 2-3mg/dL for the coloration to be easily visible. Jaundice is not an illness, but a medical condition in which too much bilirubin – a compound produced by the breakdown of hemoglobin from red blood cells – is circulating in the blood. This excess of bilirubin causes the skin, eyes and the mucus membranes (inside of the mouth) to turn a yellowish color. This yellowish color is due to the bilirubin dissolving in the fat layer just below the skin.

The most important function of the liver is the processing of chemical waste products like cholesterol and excreting them into the intestines as bile. The liver is the premier chemical factory in the body--most incoming and outgoing chemicals pass through it. It is the first stop for all nutrients, toxins, and drugs absorbed by the digestive tract. The liver also collects chemicals from the blood for processing. Many of these outward-bound chemicals are excreted into the bile. One particular substance, bilirubin, is yellow. Bilirubin is a product of the breakdown of hemoglobin, which is the protein inside red blood cells. If bilirubin cannot leave the body, it accumulates and discolors other tissues. The normal total level of bilirubin in blood serum is between 0.2 mg/dL and 1.2 mg/dL. When it rises to 3 mg/dL or higher, the person's skin and the whites of the eyes become noticeably yellow.

Bile is formed in the liver. It then passes into the network of hepatic bile ducts, which join to form a single tube. A branch of this tube carries bile to the gallbladder, where it is stored, concentrated, and released on a signal from the stomach. Food entering the stomach is the signal that stimulates the gallbladder to release the bile. The tube, which is now called the common bile duct, continues to the intestines. Before the common bile duct reaches the intestines, it is joined by another duct from the pancreas. The bile and the pancreatic juice enter the intestine through a valve called the ampulla of Vater. After entering the intestine, the bile and pancreatic secretions together help in the process of digestion.

Jaundice is very common in a mild and transient form in newborn babies, and it is most often a harmless and easily remedied condition. It is caused by the baby having a higher blood count than needed and the blood cells are broken down. Severe cases are treated with special lights, called bililights, which break down the bilirubin.

What is bilirubin ?

When red blood cells are removed from the bloodstream, hemoglobin, the molecule in red cells that carries oxygen, is broken down into bilirubin. The hemoglobin is rapidly converted to bilirubin in the blood. The bilirubin is removed from the
blood by the liver, modified, and excreted into the bile. The bile flows into the intestine so that the bilirubin is eliminated in the stool. (It is bilirubin that gives stool its brown color.) Jaundice can occur whenever this normal process of destruction of red blood cells and elimination of bilirubin is interrupted. This occurs when there is abnormally increased destruction of red blood cells (hemolysis), liver disease that reduces the ability of the liver to remove and modify bilirubin, or obstruction to the flow of bile into the intestine.

Jaundice can be dangerous if the bilirubin reaches too high a level in the blood. The level at which it becomes dangerous will vary based on a child's age and if there are other medical conditions. A small sample of your baby's blood can be tested to measure the bilirubin level. Other tests may be needed to see if your baby has a special reason to make extra bilirubin that is causing the jaundice.

What causes jaundice ?

When red blood cells die, the heme in their hemoglobin is converted to bilirubin in the spleen. The bilirubin is processed by the liver, enters bile and is eventually excreted through feces. Once hemoglobin is in the red cells of the blood, it circulates for the life span of those cells. The hemoglobin that is released when the cells die is turned into bilirubin. If for any reason the RBCs die at a faster rate than usual, bilirubin can accumulate in the blood and cause jaundice.

Once hemoglobin is in the red cells of the blood, it circulates for the life span of those cells. The hemoglobin that is released when the cells die is turned into bilirubin. If for any reason the RBCs die at a faster rate than usual, bilirubin can accumulate in the blood and cause jaundice.

Pre-hepatic (or hemolytic) jaundice is caused by anything which causes an increased rate of haemolysis (breakdown of red blood cells). In tropical countries, malaria can cause jaundice in this manner. Certain genetic diseases, such as glucose 6-phosphate dehydrogenase deficiency can lead to increase red cell lysis and therefore hemolyic jaundice. Defects in bilirubin metabolism also present as jaundice.

Liver diseases of all kinds threaten the organ's ability to keep up with bilirubin processing. Starvation, circulating infections, certain medications, hepatitis, and cirrhosis can all cause hepatic jaundice, as can certain hereditary defects of liver chemistry, including Gilbert's syndrome and Crigler-Najjar syndrome. Hepatic causes include acute hepatitis, hepatotoxicity and alcoholic liver disease. Less common causes include primary biliary cirrhosis, Gilbert's syndrome and metastatic carcinoma. Jaundice commonly seen in the newborn baby is another example of hepatic jaundice.

Post-hepatic forms of jaundice include the jaundices caused by failure of soluble bilirubin to reach the intestines after it has left the liver. These disorders are called obstructive jaundices. The most common cause of obstructive jaundice is the presence of gallstones in the ducts of the biliary system. Other causes have to do with birth defects and infections that damage the bile ducts; drugs; infections; cancers; and physical injury. Some drugs--and pregnancy on rare occasions--simply cause the bile in the ducts to stop flowing. Post-hepatic (or obstructive) jaundice, also called cholestasis, is caused by an interruption to the drainage of bile in the biliary system. The most common causes are gallstones in the common bile duct and pancreatic cancer in the head of the pancreas. Other causes include strictures of the common bile duct, ductal carcinoma, pancreatitis and pancreatic pseudocysts. A rare cause of obstructive jaundice is Mirizzi's syndrome. The presence of pale stools suggests an obstructive or post-hepatic cause as normal feces get their colour from bile pigments.

What are the symptoms of jaundice ?

Jaundice is the yellow staining of the skin and sclerae (the whites of the eyes) by abnormally high blood levels of the bile pigment, bilirubin. The yellowing extends to other tissues and body fluids and also may turn the urine dark. Yellowing of only the skin also can be caused by eating too many carrots or drinking too much carrot juice. The urine is often dark because excess bilirubin is excreted through the kidneys. Other symptoms, such as itching and light-colored stools, may appear, depending on the underlying cause of the jaundice. For example, acute inflammation of the liver (acute hepatitis) may cause loss of appetite, nausea, vomiting, and fever. Blockage of bile may produce the symptoms of cholestasis.

What's newborn jaundice ?

Jaundice is very common in newborn babies due to the fact that the newborn liver is not able to cope with the normal breakdown of red blood cells. Normal newborn jaundice is the result of two conditions occurring at the same time--a pre-hepatic and a hepatic source of excess bilirubin. First of all, the baby at birth immediately begins converting hemoglobin from a fetal type to an adult type. The fetal type of hemoglobin was able to extract oxygen from the lower levels of oxygen in the mother's blood. At birth the infant can extract oxygen directly from his or her own lungs and does not need the fetal hemoglobin any more. So fetal hemoglobin is removed from the system and replaced with adult hemoglobin. The resulting bilirubin loads the system and places demands on the liver to clear it. But the liver is not quite ready for the task, so there is a period of a week or so when the liver has to catch up. During that time the baby is jaundiced.

In the newborn, jaundice first becomes visible on the face. As levels of bilirubin go up, the jaundice will move from head to toe. By the time an infant is jaundiced all over, bilirubin levels should be measured. Just looking at the baby is not an accurate test. Color can be influenced by many things, such as lighting or the color of the walls. Infants with higher levels of jaundice look more orange than yellow. The jaundice is more intense. Babies with higher bilirubin levels often are motionless and do not feed well.

What causes newborn baby jaundice ?

A baby born prematurely is more at risk for jaundice. Infection, not getting enough oxygen during birth, and some medicines may increase the baby's risk of jaundice. At birth, babies have a relatively immature liver function. Therefore, jaundice is
present to some degree in almost all newborns. Even the normal destruction of red blood cells by the liver in the newborn infant can cause jaundice. This form of jaundice usually appears between the 2nd and 5th days of life and clears by 2 weeks. It usually causes no problems.

Blood incompatibility ("ABO" incompatibility) is a common cause. It happens when the baby's major blood groups differ from the mother's. The most common group incompatibility is when the baby's blood type is "A", "B", or "AB" and the mother's blood type is "O". The mother can create antibodies to the baby's blood group. Damage to the baby's blood results in high levels of bilirubin in the blood. Bilirubin is harmless in low levels, but if the levels are very high, injury to the nervous system and brain occur. In most cases this problem is picked up shortly after birth with normal screening of babies who are born from group "O" mothers.

Breast feeding mothers often experience persisting jaundice or jaundice without blood group incompatibilities. There appears to be an association with breast feeding and exaggerated jaundice. There are certain chemicals produced in breast milk which seem to enhance normal jaundice. Breast-feeding jaundice is seen in 5-10% of newborns. It is similar to physiologic jaundice, but bilirubin levels tend to be slightly higher. This occurs when breast-fed babies do not take in enough breast milk and rarely requires treatment.

Sometimes a baby swallows blood during birth. This swallowed blood is broken down in the baby's intestines and absorbed into the bloodstream. Just as the excess blood from a blood clot will cause a rise in serum bilirubin, so will this.

What's the treatment for infant jaundice ?

Treatment is usually unnecessary. In all cases, it is important to keep the baby well-hydrated (breast milk and formula are preferable to glucose water) and encourage frequent bowel movements by feeding frequently. This is because broken down bilirubin is carried out of the body by the intestines in the stools (bilirubin is what gives stool their brown color).

Newborns are the only major category of patients in whom the jaundice itself requires attention. Because the insoluble bilirubin can get into the brain, the amount in the blood must not go over certain levels. If there is reason to suspect increased hemolysis in the newborn, the bilirubin level must be measured repeatedly during the first few days of life. If the level of bilirubin shortly after birth threatens to go too high, treatment must begin immediately. Exchanging most of the baby's blood was the only way to reduce the amount of bilirubin until a few decades ago. Then it was discovered that bright blue light will render the bilirubin harmless.

Sometimes artificial lights are used on infants whose levels are very high, or in premature infants. These lights work by helping to break down bilirubin in the skin. The infant is placed naked under artificial light in a protected isolette to maintain constant temperature. The eyes are protected from the light.

In the most severe cases of jaundice, an exchange transfusion is required. In this procedure, the baby's blood is replaced with fresh blood. Recently, promising studies have shown that treating severely jaundiced babies with intravenous immunoglobulin is very effective at reducing the bilirubin levels to safe ranges.

1 comment:

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