Liver Development and Function
Liver Development and Function
The largest of the body's organs, with the greatest number of functions.
The liver is the largest of the body's organs. It produces major proteins and chemicals, purifies the blood, converts food to energy and stores it in the form of glucose, and excretes unwanted substances. One of the primary chemicals produced by the liver is bile, which facilitates the digestion of fats in the small intestine. The liver is present by the third week after conception and begins basic functioning by the sixth or eighth week. However, the liver's ability to break down bilirubin and bile acids is still rudimentary at birth. Development continues until sometime between the ages of six months to one year when the liver reaches adult-level functioning.
Jaundice, brought on by the buildup of bilirubin in the bile, is a common feature of liver dysfunction. It is characterized by yellow skin and yellow in the whites of the eyes. Newborns are the most susceptible because liver function is still immature. In many cases, newborn jaundice is a harmless and short-lived form called physiologic jaundice that disappears in a few days. However, 15% of newborns with jaundice require treatment. Jaundice in older children generally signals an underlying disease.
The most common liver diseases among children and adolescence are biliary atresia, hepatitis, Reye's syndrome, alpha-1-antitrypsin deficiency, galactosemia, and Wilson's disease. Biliary atresia is a severe, non-hereditary defect in the ducts that carry bile away from the liver. It is present in one of every 25,000 live births. Twice as many girls as boys are affected. The cause is not known but thought to result from in utero viral blood infection, a metabolic defect, or a biological poison in the bile duct cells. In affected infants, jaundice occurs within three to six weeks after birth. The liver is enlarged; the
Hepatitis, an inflammation of the liver, is primarily caused by a viral infection contracted by eating food or drinking water contaminated with human excrement. Hepatitis can also occur from the ingestion of excess chemicals or toxic substances. Children in day care are on the Centers for Disease Control and Prevention's high risk list for Hepatitis A. Acute cases usually dissipate in six months. Hepatitis B is the more severe form, particularly for infants. A vaccine is available for susceptible children, particularly those on dialysis or babies born to women with Hepatitis B. Children with Down syndrome are also at risk to contract Hepatitis B. The virus develops slowly with fever, headache, muscle aches, loss of appetite, and an itchy rash. Symptoms then increase to nausea, vomiting, abdominal and joint pain, and foul breath.
Reye's syndrome is a serious condition leading to the rapid deterioration of the liver and the development of encephalopathy (brain disease). The ammonia-processing properties of the liver are affected, causing the ammonia to accumulate and pass into the bloodstream and brain. It can affect children from the age of one through adolescence, and generally occurs during the winter months. Children with the chicken pox, influenza and other viral infections are particularly at risk. Reye's syndrome usually develops two to seven days after the virus's onset. A child might exhibit forceful vomiting, drowsiness, hallucinations, delirium, and unusually aggressive or uncooperative behavior. Twenty to thirty percent of children with severe cases of Reye's syndrome die from extensive brain damage. There is strong evidence that aspirin can contribute to the risk, therefore parents are advised to use alternative pain and fever relievers in the treatment of viruses.
Galactosemia is an inherited enzyme deficiency affecting the digestion of milk sugars. The sugars build up in the liver, spread to other organs and, if left untreated, lead to cirrhosis, cataracts, and brain damage. It is often confused with lactose intolerance. The affected child may exhibit vomiting, weight loss, and lethargy. Treatment is the complete removal of milk from the child's diet as well as many fruits and vegetables that contain galactose.
Wilson's disease is a rare inherited abnormality caused by the accumulation of copper in the liver, resulting in cirrhosis and brain damage. Although present at birth, the symptoms may take five years to surface. When the copper invades the red blood.cells, severe anemia results. Affected children may have a gold-brown or graygreen ring at the edge of the cornea. Treatment includes restricting the ingestion of copper-rich foods such as shellfish, organ meats, legumes, nuts, whole grain cereals, and chocolate; and the administering of the drug penicillamine (known commercially as Cuprunine or Depen).
Alpha-1-antitrypsin deficiency is the most common genetic cause of liver disease in children. Although it is present in one out of every 2,000 births in the United States, only 10-20% of affected children will develop liver disease. Symptoms in the infant include jaundice, abdominal swelling, and inefficient feeding. When it occurs in childhood or adolescence, symptoms include fatigue, poor appetite, abdominal swelling, and leg swelling. Al- though alpha-1-antitrypsin deficiency cannot be cured, it can be treated through a regiment of multiple vitamins and vitamins E, D, and K to provide essential nutrients. If liver failure develops, a transplant is recommended.
