Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme metabolism, liver dysfunction, or biliary-tract obstruction. The prevalence of jaundice in adults is rare, while jaundice in babies is common, with an estimated 80% affected during their first week of life. The most commonly associated symptoms of jaundice are itchiness, pale feces, and dark urine.
Normal levels of bilirubin in blood are below 1.0 mg/dl (17 μmol/L), while levels over 2–3 mg/dl (34–51 μmol/L) typically result in jaundice. High blood bilirubin is divided into two types – unconjugated and conjugated bilirubin.
Causes of jaundice vary from relatively benign to potentially fatal. High unconjugated bilirubin may be due to excess red blood cell breakdown, large bruises, genetic conditions such as Gilbert's syndrome, not eating for a prolonged period of time, newborn jaundice, or thyroid problems. High conjugated bilirubin may be due to liver diseases such as cirrhosis or hepatitis, infections, medications, or blockage of the bile duct, due to factors including gallstones, cancer, or pancreatitis. Other conditions can also cause yellowish skin, but are not jaundice, including carotenemia, which can develop from eating large amounts of foods containing carotene — or medications such as rifampin.
Treatment of jaundice is typically determined by the underlying cause. If a bile duct blockage is present, surgery is typically required; otherwise, management is medical. Medical management may involve treating infectious causes and stopping medication that could be contributing to the jaundice. Jaundice in newborns may be treated with phototherapy or exchanged transfusion depending on age and prematurity when the bilirubin is greater than 4–21 mg/dl (68–360 μmol/L). The itchiness may be helped by draining the gallbladder, ursodeoxycholic acid, or opioid antagonists such as naltrexone. The word "jaundice" is from the French jaunisse, meaning "yellow disease".
Signs and symptoms
The most common signs of jaundice in adults are a yellowish discoloration of the white area of the eye (sclera) and skin with scleral icterus presence indicating a serum bilirubin of at least 3 mg/dl. Other common signs include dark urine (bilirubinuria) and pale (acholia) fatty stool (steatorrhea). Because bilirubin is a skin irritant, jaundice is commonly associated with severe itchiness.
Eye conjunctiva has a particularly high affinity for bilirubin deposition due to high elastin content. Slight increases in serum bilirubin can, therefore, be detected early on by observing the yellowing of sclerae. Traditionally referred to as scleral icterus, this term is actually a misnomer, because bilirubin deposition technically occurs in the conjunctival membranes overlying the avascular sclera. Thus, the proper term for the yellowing of "white of the eyes" is conjunctival icterus.
A much less common sign of jaundice specifically during childhood is yellowish or greenish teeth. In developing children, hyperbilirubinemia may cause a yellow or green discoloration of teeth due to bilirubin deposition during the process of tooth calcification. While this may occur in children with hyperbilirubinemia, tooth discoloration due to hyperbilirubinemia is not observed in individuals with adult-onset liver disease. Disorders associated with a rise in serum levels of conjugated bilirubin during early development can also cause dental hypoplasia.
Causes
Jaundice is a sign indicating the presence of an underlying diseases involving abnormal bilirubin metabolism, liver dysfunction, or biliary-tract obstruction. In general, jaundice is present when blood levels of bilirubin exceed 3 mg/dl. Jaundice is classified into three categories, depending on which part of the physiological mechanism the pathology affects. The three categories are:
Prehepatic causes
Prehepatic jaundice is most commonly caused by a pathological increased rate of red blood cell (erythrocyte) hemolysis. The increased breakdown of erythrocytes → increased unconjugated serum bilirubin → increased deposition of unconjugated bilirubin into mucosal tissue. These diseases may cause jaundice due to increased erythrocyte hemolysis: Sickle-cell anemia Spherocytosis Thalassemia Pyruvate kinase deficiency Glucose-6-phosphate dehydrogenase deficiency Microangiopathic hemolytic anemia Hemolytic-uremic syndrome Severe malaria (in endemic countries)