Signs and symptoms

Jaundice
Jaundice, (also known as icterus, attributive adjective: icteric) is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae (whites of the eyes), and other mucous membranes caused by hyperbilirubinemia (increased levels of bilirubin in the blood). This hyperbilirubinemia subsequently causes increased levels of bilirubin in the extracellular fluids. Typically, the concentration of bilirubin in the plasma must exceed 1.5 mg/dL[1] ( > 35 micromoles/L), three times the usual value of approximately 0.5 mg/dL[1], for the coloration to be easily visible. Jaundice comes from the French word jaune, meaning yellow.

One of the first tissues to change color as bilirubin levels rise in jaundice is the conjunctiva of the eye, a condition sometimes referred to as scleral icterus. However, the sclera themselves are not "icteric" (stained with bile pigment) but rather the conjunctival membranes that overlie them. The yellowing of the "white of the eye" is thus more properly conjunctival icterus

Signs and symptoms
A 4-year old boy with an icteric (Jaundiced) sclera which later proved to be a manifestation of hemolytic anemia due to G6PD deficiency following fava bean consumption.
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Eyes

It was once believed persons suffering from the medical condition jaundice saw everything as yellow. By extension, the jaundiced eye came to mean a prejudiced view, usually rather negative or critical. Alexander Pope, in "An Essay on Criticism" (1711), wrote: “All seems infected to the infected spy, As all looks yellow to the jaundiced eye.”[3] Similarly in the mid-19th century the English poet Alfred Lord Tennyson wrote in the poem “Locksley Hall”: “So I triumphe'd ere my passion sweeping thro' me left me dry, left me with the palsied heart, and left me with a jaundiced eye.”

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Differential diagnosis
Types of jaundice

When a pathological process interferes with the normal functioning of the metabolism and excretion of bilirubin just described, jaundice may be the result. Jaundice is classified into three categories, depending on which part of the physiological mechanism the pathology affects. The three categories are:Category Definition

Pre-hepatic The pathology is occurring prior to the liver.
Hepatic The pathology is located within the liver.
Post-Hepatic The pathology is located after the conjugation of bilirubin in the liver.

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Pre-hepatic

Pre-hepatic jaundice is caused by anything which causes an increased rate of hemolysis (breakdown of red blood cells). In tropical countries, malaria can cause jaundice in this manner. Certain genetic diseases, such as sickle cell anemia, spherocytosis, thalassemia and glucose 6-phosphate dehydrogenase deficiency can lead to increased red cell lysis and therefore hemolytic jaundice. Commonly, diseases of the kidney, such as hemolytic uremic syndrome, can also lead to coloration. Defects in bilirubin metabolism also present as jaundice. Jaundice usually comes with high fevers. Rat fever (leptospirosis) can also cause jaundice.

Laboratory findings include:

Urine: no bilirubin present, urobilirubin > 2 units (i.e., hemolytic anemia causes increased heme metabolism; exception: infants where gut flora has not developed).
Serum: increased unconjugated bilirubin.
Kernicterus is associated with increased unconjugated bilirubin
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Hepatocellular

Hepaticellular (Hepatic) (in hepatocellular jaundice there is invariably cholestasis) jaundice causes include acute hepatitis, hepatotoxicity, Gilbert's syndrome (a genetic disorder of bilirubin metabolism which can result in mild jaundice, which is found in about 5% of the population), Crigler-Najjar syndrome and alcoholic liver disease, whereby cell necrosis reduces the liver's ability to metabolize and excrete bilirubin leading to a buildup of unconjugated bilirubin in the blood. Other causes include primary biliary cirrhosis leading to an increase in plasma conjugated bilirubin. Jaundice seen in the newborn, known as neonatal jaundice, is common, occurring in almost every newborn as hepatic machinery for the conjugation and excretion of bilirubin does not fully mature until approximately two weeks of age.

Laboratory findings depend on the cause of jandice.

Urine: Conjugated bilirubin present, urobilirubin > 2 units but variable (except in children). Kernicterus is a condition not associated with increased conjugated bilirubin.
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Post-hepatic

Post-hepatic jaundice, also called obstructive jaundice, is caused by an interruption to the drainage of bile in the biliary system. The most common causes are gallstones in the common bile duct, and pancreatic cancer in the head of the pancreas. Also, a group of parasites known as "liver flukes" can live in the common bile duct, causing obstructive jaundice. Other causes include strictures of the common bile duct, biliary atresia, ductal carcinoma, pancreatitis and pancreatic pseudocysts. A rare cause of obstructive jaundice is Mirizzi's syndrome.

The presence of pale stools and dark urine suggests an obstructive or post-hepatic cause as normal feces get their color from bile pigments. However, although pale stools and dark urine are a feature of biliary obstruction, they can occur in many intra-hepatic illnesses and are therefore not a reliable clinical feature to distinguish obstruction from hepatic causes of jaundice.[4]

Patients also can present with elevated serum cholesterol, and often complain of severe itching or "pruritus".

Not one test can differentiate between various classifications of jaundice. A combination of liver function tests is essential to arrive at a diagnosis.