662
CMDT 2013
16
Liver, Biliary Tract, & Pancreas Disorders Lawrence S. Friedman, MD
JAUNDICE & EVALUATION OF ABNORMAL LIVER BIOCHEMICAL TESTS
``
E sse n t i a ls o f d i a g n o s i s
Jaundice results from accumulation of bilirubin in the body tissues; cause may be hepatic or nonhepatic. Hyperbilirubinemia may be due to abnormalities in the formation, transport, metabolism, and excretion of bilirubin. Mild elevations of the aminotransferase levels are common in clinical practice and caused most commonly by nonalcoholic fatty liver disease. Evaluation of obstructive jaundice begins with ultrasonography and is usually followed by cholangiography.
``
``
``
``
``General Considerations Jaundice (icterus) results from the accumulation of bilirubin—a product of heme metabolism—in the body tissues. Hyperbilirubinemia may be due to abnormalities in the formation, transport, metabolism, and excretion of bilirubin. Total serum bilirubin is normally 0.2–1.2 mg/dL (3.42–20.52 mcmol/L) (mean levels are higher in men than women and higher in whites and Hispanics than blacks and correlate inversely with the risk of stroke, respiratory disease, cardiovascular disease, and mortality, presumably because of an antioxidant effect). Jaundice may not be recognizable until serum bilirubin levels are about 3 mg/dL (51.3 mcmol/L). Jaundice is caused by predominantly unconjugated or conjugated bilirubin in the serum (Table 16–1). Unconjugated hyperbilirubinemia may result from overproduction of bilirubin because of hemolysis; impaired hepatic uptake of bilirubin due to certain drugs; or impaired conjugation of bilirubin by glucuronide, as in Gilbert syndrome, due to mild decreases in uridine diphosphate (UDP) glucuronyl
transferase, or Crigler–Najjar syndrome, caused by moderate decreases or absence of UDP glucuronyl transferase. Hemolysis alone rarely elevates the serum bilirubin level to more than 7 mg/dL (119.7 mcmol/L). Predominantly conjugated hyperbilirubinemia may result from impaired excretion of bilirubin from the liver due to hepatocellular disease, drugs, sepsis, hereditary hepatocanalicular transport defects (such as Dubin–Johnson syndrome, progressive familial intrahepatic cholestasis syndromes, and some cases of intrahepatic cholestasis of pregnancy), or from extrahepatic biliary obstruction. Features of some hyperbilirubinemic syndromes are summarized in Table 16–2. The term “cholestasis” denotes retention of bile in the liver, and the term “cholestatic jaundice” is often used when conjugated hyperbilirubinemia results from impaired bile flow.
``Clinical Findings A. Unconjugated Hyperbilirubinemia Stool and urine color are normal, and there is mild jaundice and indirect (unconjugated) hyperbilirubinemia with no bilirubin in the urine. Splenomegaly occurs in hemolytic disorders except in sickle cell anemia.
B. Conjugated Hyperbilirubinemia 1. Hereditary cholestatic syndromes or intrahepatic cholestasis—The patient may be asymptomatic; cholestasis is often accompanied by pruritus, light-colored stools, and jaundice. 2. Hepatocellular disease—Malaise, anorexia, low-grade fever, and right upper quadrant discomfort are frequent. Dark urine, jaundice, and, in women, amenorrhea occur. An enlarged tender liver, vascular spiders, palmar erythema, ascites, gynecomastia, sparse body hair, fetor hepaticus, and asterixis may be present, depending on the cause, severity, and chronicity of liver dysfunction.
C. Biliary Obstruction There may be right upper quadrant pain, weight loss (suggesting carcinoma), jaundice, dark urine, and light-colored stools.