Clinical Pearls & Morning Reports
A recent multicenter study examined the causes of severe acute liver injury in patients with an aspartate aminotransferase or alanine aminotransferase level of more than 1000 U per liter and confirmed the leading causes to be ischemic hepatitis, pancreaticobiliary disease, drug-induced liver injury, and viral hepatitis. Read the latest Case Records of the Massachusetts General Hospital here.
Q: What percentage of persons with exposure to hepatitis C virus (HCV) have successful viral clearance?
A: An estimated 25% of persons with exposure to HCV have successful viral clearance; female sex, symptomatic infection, and favorable host genetic factors are associated with spontaneous clearance. A landmark finding in the understanding of the immune response to HCV was the identification of single-nucleotide polymorphisms in the IL28B gene that are strongly associated with both interferon response and spontaneous viral clearance. Such favorable single-nucleotide polymorphisms have also been shown to increase the clearance of repeat infection.
Q: How common are IgM antibodies to hepatitis B virus (HBV) core antigen among patients with reactivation of chronic HBV infection?
A: If the patient’s status regarding previous exposure to HBV is unknown, it can be challenging to distinguish reactivation of chronic HBV infection from new acute HBV infection. Reactivation occurs when the virus transitions from a state of low viral replication to a period of increased replication that is accompanied by a vigorous immune response and is clinically manifested by jaundice or decompensated liver disease. Peak alanine aminotransferase and bilirubin levels tend to be lower in patients with reactivation than in patients with primary infection, and IgM antibodies to HBV core antigen are present in less than half of patients with reactivation.
A: HDV is a defective virus that depends on the presence of HBV, and that exacerbates HBV infection. There are two clinical patterns of infection with HDV: coinfection, in which exposure to HDV and to HBV are simultaneous, and superinfection, in which acute HDV infection occurs in a person with established chronic HBV infection. HDV infection remains rare in the United States. Among the persons who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2012 and had positive tests for HBV core antibodies and surface antigen, the estimated overall prevalence of HDV infection was 0.02%. NHANES data obtained from 2011 to 2016 showed a slightly higher prevalence of HDV infection, of 0.11%. However, the NHANES did not include several high-risk populations, such as homeless and incarcerated persons. In addition, the prevalence of HDV infection may be higher among persons with injection drug use. In one cohort of persons who inject drugs, testing for HDV antibodies and RNA was performed in participants who had a positive test for HBV surface antigen, and HDV infection was identified in 35.6% of the participants with chronic HBV infection. Thus, although the overall prevalence of HDV infection is very low, the rate may be higher in certain high-risk cohorts.
A: Available therapies for HDV are based on interferon-alfa but are associated with substantial side effects and have had varied results. New experimental agents, such as prenylation inhibitors and entry inhibitors, show promise but are not yet approved for use.