Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (169 page)

   Laboratory findings due to obstruction of hepatic (Budd-Chiari syndrome) or portal veins or the inferior vena cava may occur.

Suggested Readings

Friedman LS. Congestive hepatopathy.
www.uptodate.com
, May 2009.

Khan F, Sachs H, Pechet L, et al.
Guide to Diagnostic Testing
. Philadelphia, PA: Lippincott Williams & Wilkins; 2002.

Yao DF, Yao DB, Wu XH, et al. Diagnosis of hepatocellular carcinoma by quantitative detection of hepatoma-specific bands of serum γ-glutamyltransferase.
Am J Clin Pathol.
1998; 110:743.

JAUNDICE (SEE HEPATOMEGALY)

   Overview

   Jaundice is a yellowish staining of the integument, sclerae, and deeper tissues and is associated with conditions that have increased excretions of bile pigments, which are increased in the plasma.

   Physiology

   Serum bilirubin accumulates when its production from heme exceeds its metabolism and excretion.

   An imbalance between the production and clearance of serum bilirubin results either from excess release of bilirubin into the bloodstream or from physiologic processes that impair the hepatic uptake, metabolism, or excretion of this metabolite.

   Jaundice is clinically detectable when the serum bilirubin exceeds 2.0– 2.5 mg/dL. Because elastin has a high affinity for bilirubin, and scleral tissue is rich in elastin, scleral icterus is usually a more sensitive sign than generalized jaundice.

   Bilirubin metabolism

   Unconjugated bilirubin: More than 90% of serum bilirubin in normal individuals is in an unconjugated form, circulating as an albumin-bound complex. This is not filtered by the kidneys.

   Conjugated bilirubin: The remainder is conjugated (primarily as a glucuronide), rendering it water soluble, and thus capable of being filtered and excreted by the kidney.

   Hepatic phase: Hepatic metabolism has three phases: uptake, conjugation, and excretion.