An elevated concentration of serum total bilirubin is diagnostic for jaundice. The upper limit of normal is >1 mg/dL or >1.3 mg/d in some laboratories. Hyperbilirubinemia can be further categorized as conjugated or unconjugated. Serum conjugated bilirubin concentration >0.4 mg/dL (6.8 micromol/L) revealed conjugated hyperbilirubinemia. In unconjugated hyperbilirubinemia conjugated bilirubin is <1 mg/dL (17 micromol/L) if the total bilirubin is <5 mg/dL, or less than 20 percent of the total bilirubin if the total bilirubin is >5 mg/dL (85 micromol/L).

Laboratory findings consistent with the diagnosis of jaundice include:^[1][2]

• An elevated concentration of serum total bilirubin (Normal 0 – 1 mg/dL).

• Hyperbilirubinemia can be further categorized as conjugated or unconjugated:
  • Conjugated hyperbilirubinemia:
    • Serum conjugated bilirubin concentration >0.4 mg/dL (6.8 micromol/L).
    • Direct bilirubin >1 mg/dL (17 micromol/L) if the total bilirubin is <5 mg/dL (85 micromol/L).
    • More than 20 percent of the total bilirubin if the total bilirubin is >5 mg/dL (85 micromol/L).
  • Unconjugated hyperbilirubinemia:
    • Conjugated bilirubin is <1 mg/dL (17 micromol/L) if the total bilirubin is <5 mg/dL.
    • Less than 20 percent of the total bilirubin if the total bilirubin is >5 mg/dL (85 micromol/L).

• Alkaline phosphatase:
  • Elevated alkaline phosphatase may suggest the following as underlying cause of jaundice:^[3]
    • Gallstones causing bile duct obstruction
    • Pancreatic cancer
    • Pregnancy
    • Drugs
    • Rarely primary biliary cirrhosis
• Liver transaminases
  • Very high serum transaminases may suggest viral hepatitis as the underlying disease.^[4]
  • Most causes of liver cell injury are associated with a greater increase in ALT than AST.
  • AST to ALT ratio of 2:1 or greater is suggestive of alcoholic liver disease.
• Gamma-glutamyltransferase (GGT):^[5][6]
  • A raised mean corpuscular volume (MCV) with raised GGT may suggest alcohol abuse. If accompanied by raised ALT, it suggests liver cell damage as the underlying disease for jaundice.
  • Very high GGT levels (x 10 normal) may suggest biliary obstruction and hepatic malignancies as the underlying disease for jaundice.
  • Raised GGT with raised alkaline phosphatase (more than 3 times) may suggest cholestasis as the underlying disease for jaundice.

• Decreased red blood cells and hemoglobin may suggest hemolysis as the underlying disease for jaundice.

• Erythrocyte sedimentation rate may be elevated in primary biliary cirrhosis as the underlying disease for jaundice.^[7]

• Elevated lactate dehydrogenase is diagnostic of hemolysis as the underlying disease for jaundice.

• For more information about viral hepatitis serology click here.

• Anti-nuclear antibodies (ANAs)
  • Antinuclear antibody (ANA) may be raised in primary biliary cirrhosis(20-30%).^[7]
• Anti-smooth muscle antibody (ASMA):
  • Anti-smooth muscle antibodies are antibodies (immunoglobulins) formed against smooth muscle. These antibodies are typically associated with autoimmune hepatitis.^[8]
• Anti-mitochondrial antibodies (AMA):
  • Elevated antimitochondrial antibodies suggests primary biliary cirrhosis (90-95% of patients).^[7]

• Elevated IgG may suggest acute hepatitis as the underlying disease for jaundice.^[9]
• Elevated IgM may suggest primary biliary cirrhosis as the underlying disease for jaundice.^[7]

• Decreased alpha-1-antitrypsin may suggests cirrhosis as the underlying disease for jaundice.^[10]