jaundice

Jaundice is a yellow discoloration of the skin and sclera caused by elevated bilirubin in the blood. Bilirubin is produced from heme breakdown; it circulates as unconjugated (indirect) bilirubin and, after processing in the liver, as conjugated (direct) bilirubin. Jaundice is usually visible when total bilirubin exceeds about 2–3 mg/dL in adults.

Causes are commonly grouped as prehepatic, hepatic, and posthepatic. Prehepatic causes include increased bilirubin production from hemolysis or genetic conditions such as Gilbert syndrome. Hepatic causes involve impaired bilirubin processing or hepatocellular disease (for example, viral hepatitis, alcoholic liver disease, drug-induced injury, cirrhosis). Posthepatic causes are due to obstruction of bile flow from gallstones, tumors, or pancreatic disease. Neonatal jaundice is common in newborns and often reflects immature liver conjugation of bilirubin.

Clinically, jaundice presents with yellowing of the eyes and skin; dark urine and pale stools may accompany cholestasis. The pattern of bilirubin fractions helps narrow the cause: predominantly unconjugated bilirubin suggests overproduction or impaired conjugation, while predominantly conjugated bilirubin suggests biliary obstruction or cholestasis. Additional signs of liver disease or biliary pathology may be present.

Diagnosis relies on history, physical examination, and laboratory tests. Measurements include total and direct bilirubin, liver enzymes (ALT, AST, ALP, GGT), albumin, and coagulation tests; complete blood count can reveal hemolysis or infection. Imaging such as ultrasound or MRCP may assess obstruction. Neonatal evaluation often uses transcutaneous bilirubin measurement and serum levels.

Management targets the underlying cause. Treatment may include monitoring, antiviral or anti-inflammatory therapy for hepatitis, procedures to relieve obstruction, or supportive care for neonatal jaundice (phototherapy) when indicated. Prognosis depends on the cause and response to treatment; jaundice itself is a sign rather than a disease.