Jaundice
Medical Author:
Jay Marks, M.D.Medical Editor:
Dennis Lee, M.D.
What is jaundice?
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.
What causes jaundice?
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.
Jaundice occurs when there is 1) too much bilirubin being produced for the liver
to remove from the blood. (For example, patients with hemolytic anemia have an
abnormally rapid rate of destruction of their red blood cells that releases
large amounts of bilirubin into the blood), 2) a defect in the liver that
prevents bilirubin from being removed from the blood, converted to
bilirubin/glucuronic acid (conjugated) or secreted in bile, or 3) blockage of
the bile ducts that decreases the flow of bile and bilirubin from the liver into
the intestines. (For example, the bile ducts can be blocked by cancers,
gallstones, or inflammation of the bile ducts). The decreased conjugation,
secretion, or flow of bile that can result in jaundice is referred to as
cholestasis: however, cholestasis does not always result in jaundice.
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