DEFINITIONS AND EPIDEMIOLOGY
Hepatitis is an inflammation of the liver, which can be caused by a variety of factors including: auto-immunity, metabolic abnormalities, or exposure to an infectious agent, drug, or toxin. Hepatitis can present as an acute process or as a chronic, progressive disease, depending on the underlying cause of illness.
Viral hepatitis can be caused by a variety of pathogens, leading to acute and chronic liver disease. Depending on the pathogen and patient factors such as age and immune status, the spectrum of presentation ranges from asymptomatic hepatitis to fulminant liver failure. Acute hepatitis is suggested by jaundice, scleral icterus, pruritus, hypercoagulability, and sometimes encephalopathy in patients. There may or may not be a recent history of fever and malaise. Laboratory testing typically demonstrates elevated aminotransferase levels with or without elevated serum bilirubin levels (cholestasis). Chronic hepatitis is often subclinical and apparent by only moderate elevation of serum aminotransferase levels in the pediatric population but with progressive hepatic fibrosis and cirrhosis from ongoing inflammatory liver injury. There may be splenomegaly and ascites from portal hypertension, and there is additionally a risk of hepatocellular carcinoma. If liver injury is suspected—whether acute or chronic—the most important laboratory parameter to obtain is the International Normalized Ratio (INR) as an indicator of hepatic synthetic function and possible liver failure.
There remains a broad differential diagnosis for acute and chronic hepatitis with etiologies including inflammatory, infectious, autoimmune, metabolic, and drugs and/or toxins.1 Table 43-1 outlines common etiologies accounting for acute and chronic hepatitis.
TABLE 43-1Differential Diagnosis of Acute and Chronic Liver Injury |Favorite Table|Download (.pdf) TABLE 43-1 Differential Diagnosis of Acute and Chronic Liver Injury
|Acute hepatitis || |
|Chronic hepatitis || |
Bile salt export pump (BSEP) deficiency
Familial intrahepatic cholestasis (FIC1)
Multidrug-resistant 3 (MDR3) deficiency
Primary sclerosing cholangitis
Glycogen storage disease
Nonalcoholic fatty liver disease
While the differential diagnosis of viral hepatitis also includes Epstein–Barr virus, cytomegalovirus, coxsackievirus, herpes simplex virus (HSV), human herpesvirus 6, and influenza, among others, this discussion will be limited to hepatitis A, B, C, D, and E. Table 43-2 outlines the salient features of these other viral etiologies.
TABLE 43-2Other Viral Pathogens that Can Cause an Acute Hepatitis, Their Salient Clinical, and Proposed Evaluation |Favorite Table|Download (.pdf) TABLE 43-2 Other Viral Pathogens that Can Cause an Acute Hepatitis, Their Salient Clinical, and Proposed Evaluation
|Viral Pathogen ||Clinical Features ||Testing |
|Adenovirus ||Severe hepatitis in immunocompromised patients ||Qualitative PCR from blood |
|Cytomegalovirus (CMV) ||Infectious mononucleosis || |
Qualitative PCR from blood
CMV IgM and CMV IgG
|Epstein–Barr virus (EBV) ||Infectious mononucleosis || |
Qualitative PCR from blood
EBV IgM and EBV IgG
|Herpes simplex virus (HSV)...|