What is Jaundice?
Jaundice is a yellow discoloration of the skin, mucous membranes, and the whites of the eyes caused by increased amounts of bilirubin in the blood. Jaundice is a sign of an underlying disease process.
Bilirubin is a by-product of the daily natural breakdown and destruction of red blood cells in the body. The hemoglobin molecule that is released into the blood by this process is split, with the heme portion undergoing a chemical conversion to bilirubin. Normally, the liver metabolizes and excretes the bilirubin in the form of bile. However, if there is a disruption in this normal metabolism and/or production of bilirubin, jaundice may result.
What Causes Jaundice?
Jaundice may be caused by several different disease processes. It is helpful to understand the different causes of jaundice by identifying the problems that disrupt the normal bilirubin metabolism and/or excretion.
Pre-hepatic (before bile is made in the liver)
Jaundice in these cases is caused by rapid increase in the breakdown and destruction of the red blood cells (hemolysis), overwhelming the liver's ability to adequately remove the increased levels of bilirubin from the blood.
Examples of conditions with increased breakdown of red blood cells include:
- sickle cell crisis,
- glucose-6-phosphate dehydrogenase deficiency (G6PD),
- drugs or other toxins, and
- autoimmune disorders.
Hepatic (the problem arises within the liver)
Jaundice in these cases is caused by the liver's inability to properly metabolize and excrete bilirubin. Examples include:
Post-hepatic (after bile has been made in the liver)
Jaundice in these cases, also termed obstructive jaundice, is caused by conditions which interrupt the normal drainage of conjugated bilirubin in the form of bile from the liver into the intestines.
Causes of obstructive jaundice include:
Jaundice in newborn babies can be caused by several different conditions, although it is often a normal physiological consequence of the newborn's immature liver. Even though it is usually harmless under these circumstances, newborns with excessively elevated levels of bilirubin from other medical conditions (pathologic jaundice) may suffer devastating brain damage (kernicterus) if the underlying problem is not addressed. Newborn jaundice is the most common condition requiring medical evaluation in newborns.
The following are some common causes of newborn jaundice:
This form of jaundice is usually evident on the second or third day of life. It is the most common cause of newborn jaundice and is usually a transient and harmless condition. Jaundice is caused by the inability of the newborn's immature liver to process bilirubin from the accelerated breakdown of red blood cells that occurs at this age. As the newborn's liver matures, the jaundice eventually disappears.
Maternal-fetal blood group incompatibility (Rh, ABO)
This form of jaundice occurs when there is incompatibility between the blood types of the mother and the fetus. This leads to increased bilirubin levels from the breakdown of the fetus' red blood cells (hemolysis).
Breast milk jaundice
This form of jaundice occurs in breastfed newborns and usually appears at the end of the first week of life. Certain chemicals in breast milk are thought to be responsible. It is usually a harmless condition that resolves spontaneously. Mothers typically do not have to discontinue breastfeeding.
This form of jaundice occurs when the breastfed newborn does not receive adequate breast milk intake. This may occur because of delayed or insufficient milk production by the mother or because of poor feeding by the newborn. This inadequate intake results in dehydration and fewer bowel movements for the newborn, with subsequent decreased bilirubin excretion from the body.
Cephalohematoma (a collection of blood under the scalp)
Sometimes during the birthing process, the newborn may sustain a bruise or injury to the head, resulting in a blood collection/blood clot under the scalp. As this blood is naturally broken down, sudden elevated levels of bilirubin may overwhelm the processing capability of the newborn's immature liver, resulting in jaundice.