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Overview
Jaundice is not
a disease but rather a sign that can occur in many different diseases. Jaundice
is the yellowish staining of the skin and sclerae (the whites of the eyes) that
is caused by high levels in blood of the chemical bilirubin. The color of the
skin and sclerae vary depending on the level of bilirubin. When
the bilirubin level is mildly elevated, they are yellowish. When the bilirubin
level is high, they tend to be brown.
Bilirubin comes from red blood cells.
When red blood cells get old, they
are destroyed. Hemoglobin, the iron-containing chemical in red blood cells that
carries oxygen, is released from the destroyed red blood cells after the iron
it contains is removed. The chemical that remains in the blood after the iron
is removed becomes bilirubin. The
liver has many functions. One of the liver's functions is to produce and secrete
bile into the intestines to help digest dietary fat. Another is to remove toxic
chemicals or waste products from the blood, and bilirubin is a waste product.
The liver removes bilirubin from the blood. After
the bilirubin has entered the liver cells, the cells conjugate (attaching other
chemicals, primarily glucuronic acid) to the bilirubin, and then secrete the bilirubin/glucuronic
acid complex into bile. The complex that is secreted in bile is called conjugated
bilirubin. The conjugated bilirubin
is eliminated in the feces. (Bilirubin is what gives feces its brown color.) Conjugated
bilirubin is distinguished from the bilirubin that is released from the red blood
cells and not yet removed from the blood, which is termed unconjugated bilirubin. <<back |