Jaundice
Jaundice is a yellowish discoloration of the skin, mucous membranes and of the white of the eyes caused by elevated levels of the chemical bilirubin in the blood (hyperbilirubinemia). The term jaundice is derived from the French word jaune, which means yellow. Jaundice is not a disease per se, but rather a visible sign of an underlying disease process.Jaundice is typically seen when the level of bilirubin in the blood exceeds 2.5-3 mg/dL (milligrams per deciliter).Jaundice in adults can be caused by a variety of medical conditions, some of which are serious and potentially life-threatening.Any adult who develops jaundice needs to undergo a comprehensive medical evaluation in order to determine its cause.
What causes jaundice in adults?
Jaundice in adults is caused by various medical conditions that affect the normal metabolism or excretion of bilirubin. Bilirubin is mostly
formed from the daily breakdown and destruction of red blood cells in the bloodstream, which release hemoglobin as they rupture. The heme portion of this hemoglobin molecule is then converted into bilirubin, which is transported in the bloodstream to the liver for further metabolism and excretion. In the liver, the bilirubin is conjugated (made more water soluble), and is excreted into the gallbladder (where it is stored) and then into the intestines. In the intestines, a portion of the bilirubin is excreted in the feces, while some is metabolized by the intestinal bacteria and excreted in the urine.
Jaundice occurs if there is a dysfunction of the normal metabolism or excretion of bilirubin. This disruption in the metabolism or excretion of bilirubin can occur at various stages, and it is therefore useful to classify the different causes of jaundice based on where the dysfunction occurs. The causes of jaundice are generally classified as pre-hepatic (the problem arises before secretion to the liver), hepatic (the problem arises within the liver), and post-hepatic (the problem arises after bilirubin is excreted from the liver).
What are pre-hepatic (liver) causes of jaundice?
Jaundice caused during the pre-hepatic phase is due to the excessive destruction (hemolysis) of red blood cells from various conditions. This rapid increase in bilirubin levels in the bloodstream overwhelms the liver’s capability to properly metabolize the bilirubin, and consequently the levels of unconjugated bilirubin increase. Conditions which can lead to an increase in the hemolysis of red blood cells include:
- Malaria,
- Sickle cell disease,
- Hereditary
- spherocytosis,
- Thalassemia,
- Glucose-6-phosphate dehydrogenase deficiency (G6PD),Drugs or other toxins, and
- Autoimmune disorders.
What are hepatic (liver) causes of jaundice?
Jaundice caused during the hepatic phase can arise from abnormalities in the metabolism and/or excretion of bilirubin. This can lead to an increase in both unconjugated and/or conjugated bilirubin levels. Conditions with a hepatic cause of jaundice include: