Definition
1.  Liver edge 3.5 cms. below the right costal margin in newborns and 2 cms below the RCM in older children.  The average liver span is 4-5 cms. in newborns and 6-8 cms. in children at 12 years of age. 
2. Can find borders by palpation, percussion, and auscultation.
3. May be displaced downward by the diaphragm or thoracic contents leading to false impression of hepatomegaly.

Pathogenesis
1. Inflammation and Infection- viruses, bacteria, fungi, parasites, and autoimmune
2. Storage- glycogen, fats, proteins, metals ( iron and copper) 
3. Infiltration- primary hepatic tumors, infiltration of leukemic or lymphoma cells
4. Congestion- congestive heart failure, restrictive pericarditis, Budd Chiari
5. Obstruction of Biliary System- Atresia, cysts, stones, tumors.

Diagnosis- the evaluation of the pediatric patient with hepatomegaly should be performed in an orderly fashion based on the age of the patient, history, physical findings, laboratory evaluation, and possible radiographic studies. 

   History
     a. Jaundice- hemolysis, bile duct abnormalities, liver inflammation. 
     b. Family History of liver disease
     c. Family history of metabolic disease, neurodegenerative disease, 
     d. Weight gain and growth- will be poor with severe liver dysfunction
     e. Developmental- delay may indicate CNS storage disease
     f. Maternal infections during the pregnancy (TORCH)
     g. Umbilical catheter use in the newborn period
     h. Risk factors for hepatitis A, B, C, D, and E
     i. Acholic stools and dark urine- biliary obstruction
     j. Drug exposure
     k. Symptoms of inflammatory bowel disease
     l. Gastrointestinal bleeding
    m. Age of onset- early suggest congenital infection or metabolic disorder

  Physical Findings
     a. Fever- systemic disease or infection
     b. jaundice
     c. Splenomegaly- portal hypertension, infiltration by malignancies and storage diseases, hemolytic disease, hemoglobinopathies
    d. Increase of lymph nodes- infection or neoplasia
    e. Eye- cataracts. Keyser Fleischer rings, chorioretinitis
    f. Developmental delay and neurologic deterioration- characteristic of storage diseases and Wilson’s disease
    g. Hemangiomas and bruits
    h. Dysmorphic features ? mucopolysaccharidoses 
    i. Edema- increased venous pressure and hypoalbuminemia
    j. Ascites 

  Laboratory Evaluation- initial evaluation should be directed by the clinical presentation, past history, physical findings, and family history. 
  a. CBC and diff, platelet count, reticulocyte counts, and smear
  b. UA
  c. Aminopeptidases- indication of liver cell destruction.  Alanine aminotranasferase is more specific than aspartate aminotransferase for liver pathology
  d. PT, PTT and Albumin are markers for liver synthetic function
  e. Bilirubin- evidence of obstruction, cell damage, and hemolysis
  f. Alkaline phosphatase and gamma glutamyl transpeptidase indicate biliary obstruction
  g. Serum glucose
  h. Viral studies for Hepatitis A, B, and C

  Imaging
   a. Ultrasound- define size, consistency, small masses, and blood flow
   b. CT and MRI
  Biopsy- will demonstrate parenchymal changes, presence of storage materials, and tissue for enzyme identification. 

References
1. Wolf Ann, and Lavine Joel Hepatomegaly in Neonates and Children.  Pediatrics in Review.  Vol. 21 No. 9 September 2000
2. Agata Ian and Balisteri William.  Evaluation of Liver Disease in the Pediatric Patient Pediatrics in Review. November 1999