Jaundice laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Laboratory Findings
- Laboratory findings consistent with the diagnosis of jaundice include:
- An elevated concentration of serum total bilirubin. the upper limit of normal is >1 mg/dL or >1.3 mg/d in some laboratories. Jaundice usually becomes clinically apparent when the serum total bilirubin concentration is greater than 2 to 3 mg/dL , but threshold for clinically apparent jaundice may vary among patients.[1]
- 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), or more than 20 percent of the total bilirubin if the total bilirubin is >5 mg/dL(85 micromol/L).[1]
- 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).[1]
- Conjugated hyperbilirubinemia:
- FBC detect haemolysis.
- ESR may be rise in PBC.
- Lactate dehydrogenase elevated in haemolysis.
- LFTs:
- Alkaline phosphatase: considerably increased with either extrahepatic or intrahepatic biliary disease. The most common diseases associated with raised alkaline phosphatase include:
- Gallstones causing bile duct obstruction.
- Pancreatic cancer.
- Pregnancy.
- Drugs.
- More rarely, PBC.
- Serum transaminases are usually very high in hepatocellular disease (like viral hepatitis) but more modestly elevated in chronic hepatocellular damage and obstruction:
- Aspartate aminotransferase (AST) is raised more than alanine aminotransferase (ALT) in cirrhosis, intrahepatic neoplasia, haemolytic jaundice and alcoholic hepatitis.
- ALT is raised more than AST in acute hepatitis and in extrahepatic obstruction.
- ALT levels of less than 100 IU/L with jaundice suggest obstructive jaundice.
- ALT over 400 IU/L suggests diffuse acute hepatocellular damage (for example, in viral hepatitis).
- ALT between 150-400 IU/L suggests chronic active hepatitis or viral or drug-induced hepatitis.
- Very high levels of ALT (over 1,000 IU/L) suggest acute parenchymal disease.
- Gamma-glutamyltransferase (GGT):
- GGT is sensitive but not specific for excess alcohol intake.
- A raised MCV with raised GGT is suggestive of alcohol abuse and, if accompanied by raised ALT, suggests liver cell damage.
- Biliary obstruction and hepatic malignancies cause very high GGT levels (x 10 normal).
- Raised GGT with raised alkaline phosphatase (over x 3 normal) suggests cholestasis.
- Alkaline phosphatase: considerably increased with either extrahepatic or intrahepatic biliary disease. The most common diseases associated with raised alkaline phosphatase include:
- Hepatitis serology should be done in all patients with cholestasis, as differentiating hepatitis from extrahepatic obstructive causes may be very difficult.
- Prothrombin time may be prolonged because of vitamin K malabsorption. Injection of vitamin K will correct deficiency in cholestasis but not in parenchymal liver disease.
- Serum antinuclear antibodies (ANAs), anti-smooth muscle antibody (ASMA): the hallmark of PBC is antimitochondrial antibodies (90-95% of patients with PBC are positive); ANA is positive in 20-50% of patients with PBC.
- Serum immunoglobulins and serum electrophoresis in acute hepatitis when autoimmune hepatitis is suspected. IgG is raised in acute hepatitis, IgM is raised in autoimmune disease, PBC or chronic infection.
- Alpha-1-antitrypsin levels:
- deficiency causes cirrhosis