Type of test Blood

Normal findings

 Negative

Commonly used acute hepatitis tests or “Hepatitis Panel”

 HAV-Ab IgM

HBsAg

 HBcAb

 HCV-Ab

Test explanation and related physiology

 Hepatitis is an inflammation of the liver caused by viruses, alcohol ingestion, drugs, toxins, or overwhelming bacterial sepsis. In the United States, the most common types of hepatitis are hepatitis A, hepatitis B, and hepatitis C. Hepatitis D and hepatitis E viruses are much less common. Many people with hepatitis do not have symptoms and do not know they are infected. If symptoms occur with an acute infection, they can appear anytime from 2 weeks to 6 months after expo sure. Symptoms of chronic viral hepatitis can take decades to develop.

Hepatitis A virus (HAV) infection is usually a self-limited virus that does not become chronic. Infection causes a lifelong immunity and can be prevented with vaccination. It has a short incubation period of 2 to 6 weeks and is highly contagious. During active infection, HAV is excreted in the stool and transmitted via fecal–oral route by person-to-person contact or by contamination of food and drink. Diagnosis is made by testing for serum IgG and IgM antibodies to HAV.

Serum IgM antibodies (HAV-Ab/IgM) are detectable at the time of symptom onset (approximately 2 weeks after infection) and remain detectable for up to 6 months. Serum IgG antibodies (HAV-Ab/IgG) are detectable approximately 1-2 months after infection and can remain detectable for decades after the infection. If the IgM antibody is elevated in the absence of the IgG antibody, acute hepatitis is suspected. Elevated IgG antibodies in the absence of IgM antibodies reflect past infection or vaccina tion. The HAV virus can also be detected directly by measuring HAV RNA in the serum of patients suspected of acute infection. It can be detected earlier than HAV-Ab/IgM and is more sensitive in the early phase of HAV infection.

Hepatitis B virus (HBV) infection has a long incubation period of 1-6 months. Testing for HBV should be performed in people who have signs and symptoms of acute or chronic hepatitis. It is also tested in asymptomatic patients who are high risk of HBV exposure or high risk of adverse outcomes from infection. This includes pregnant women and babies born to HBV-infected mothers, immunosuppressed patients, persons born in areas of high HBV prevalence, persons with HIV or hepatitis C virus, IV drug users, men who have sex with men, patients with end stage renal disease, inmates of correctional facilities, and donors of blood, plasma, organ, tissue, or semen.

HBV, also called the Dane particle, is made up of an inner core surrounded by an outer capsule. The outer capsule contains the hepatitis B surface antigen (HBsAg). The inner core contains HBV core antigen (HBcAg). The hepatitis B e-antigen (HBeAg) is also found in the core. Antibodies to these antigens are called HBsAb, HBcAb, and HBeAb. The tests used to detect these antigens and antibodies include the following (Table 1):

 • Hepatitis B surface antigen (HBsAg). This is the most frequently performed test for active hepatitis B, and it is the first test result to become abnormal. HBsAg appears 1-10 weeks after exposure to HBV, which is typically before patients become symptomatic. HBsAg becomes undetectable after about 4-6 months in patients who recover. It may persist longer than 6 months in patients with chronic HBV.

 • Hepatitis B surface antibody (HBsAb or anti-HBs). This antibody appears approximately 4 weeks after the disappearance of the surface antigen and signifies the end of the acute infection. It can persist for life and signifies immunity to subsequent infection. HBsAb is the antibody that denotes immunity after administration of hepatitis B vaccine. There may be a “window” in which HBsAg is no longer detectable and HBsAb is not yet detectable. In this case, diagnosis is made by testing for antibodies to Hepatitis B core antigen (HBcAb).

• Hepatitis B core antigen (HBcAg). No serologic tests are currently available to detect this antigen.

 • Hepatitis B core antibody (HBcAb or anti-HBc). This IgM antibody is a marker of acute infection and is the sole marker of acute HBV infection during the window period between the disappearance of HBsAg and the appearance of HBsAb. It may remain elevated for 2 years after acute infection and may also elevate during exacerbation of chronic HBV infection. This can make diagnosing acute versus chronic HBV infection difficult.

• Hepatitis B e-antigen (HBeAg). This antigen is used as an indicator of replication and infectivity. The presence of HBeAg correlates with early and active disease, as well as with high infectivity in acute HBV infection. The conversion of HBeAg to antibodies against HBe (HBeAb) occurs early in acute HBV. This conversion may be delayed for many years in chronic HBV infection.

 • Hepatitis B e-antibody (HBeAb or anti-HBe). This antibody indicates that the acute phase of HBV infection is over, or in remission, and that infectivity is reduced.

Table1. Hepatitis testing

In addition to testing for serum antigens and antibodies of hepatitis B, tests for Hepatitis B DNA have been developed to test for HBV replication/viral load. HBV DNA may remain detectable in serum for many years after recovery from acute HBV infection if tested by PCR assays. The major clinical role of serum HBV DNA assays in patients with chronic HBV infection is to determine candidacy for antiviral therapy.

Hepatitis C (HCV) infection causes a variety of nonspecific symptoms in most individuals and typically results in chronic HCV infection that can be asymptomatic. Up to 30% of patients with chronic HCV progress to cirrhosis and end-stage liver dis ease over the course of several decades. Therefore, screening patients who may have an increased likelihood of being infected with HCV is important. This includes persons with any history of IV drug use, persons with history of tissue or blood transfusion prior to sensitive screening modalities, HIV patients, dialysis patients, incarcerated individuals, men who have sex with men, and persons from a country of high prevalence.

It is now recommended that individuals born between 1945 and 1965 (Baby Boomers) be tested for hepatitis C. According to the CDC, these individuals are five times more likely to have hepatitis C than other adults. It is believed that Baby Boomers may have become infected during the 1960s to 1980s when transmission of hepatitis C was at its highest. Treatments are now available that can cure hepatitis C.

Diagnostic tests for HCV include tests to detect antibodies for hepatitis C (HCV-Ab or anti-HCV) and tests to detect or quantify HCV RNA. HCV-Ab can be detected using a number of assays. The standard test used by most clinical laboratories to detect HCV-Ab in serum and plasma is an immunoassay. There are several generations of immunoassay tests, which detect antibodies that target different viral antigens and vary in accuracy. The latest, third-generation enzyme-linked immunosorbent assay (EIA-3) generally detects antibodies to recombinant antigens from the core, nonstructural protein 3 (NS3), NS4, and NS5. These tests have high sensitivity and specificity and become positive as early as 8 weeks after exposure. Several rapid immunoassay tests are also available to test for HCV-Ab. These tests can be run on finger stick blood, serum, plasma, and oral fluid. Results are generally available in less than 30 minutes. There is also an over-the-counter antibody testing kit that tests finger stick blood and is then sent to a lab. Results are returned within days.

For immunocompromised patients, HCV-Ab may not be detectable despite the presence of HCV infection, especially when earlier generation tests are used. For these patients at risk for HCV infection or in whom HCV is suspected, HCV RNA testing should be considered even if anti-HCV tests are negative. HCV RNA assays are used to confirm the presence or absence of infection and to quantify the amount of HCV RNA present. These results may be used to guide decisions regarding duration of treatment with certain regimens.

There are both qualitative and quantitative assays for HCV RNA, which are usually performed on serum or plasma from patients. Quantitative assays are used before treatment to measure baseline HCV viral load. They may also be used during and after treatment to assess response to therapy. Qualitative tests are capable of detecting low levels of HCV RNA and are used for confirming the diagnosis of HCV infection and assessing response to antiviral therapy.

Several immunoassays have been developed to detect the HCV core protein (HCV-cAg). In resource-limited settings where HCV RNA testing is not available, HCV-cAg tests can be used instead to confirm viremia.

Hepatitis D virus (HDV or delta virus) is caused by a defective virus and requires the presence of HBV for infection. Therefore, the presence of HBsAg and HBcAb is necessary for the diagnosis of acute HBV/HDV coinfection. Serum HDV antigen (HDAg) assays are currently not available for clinical diagnosis in the United States. Total (IgM and IgG) anti-HDV antibodies (HDV-Ab) can be detected by immunoassays in the United States. Total HDV-Ab appears usually after four weeks of acute HDV infection. HDV RNA can also be detected in serum by reverse transcriptase-polymerase chain reaction (RT-PCR)-based assays.

Hepatitis E virus (HEV) is one of the most common causes, yet least diagnosed etiologies, of acute viral hepatitis. Transmission can occur through contaminated food and water, blood trans fusions, and through mother-to-child transmission (perinatal). Infection is generally self-limited, although acute hepatic failure can develop in a small proportion of patients. IgM antibodies to HEV (HEV-Ab/IgM) appear during the early phase of clinical ill ness and disappear rapidly over 4 to 5 months. IgG antibodies (HEV-Ab/IgG) appear shortly after the IgM antibodies, and it is unclear how long they persist. Serum HEV RNA may be detected 2 to 6 weeks after infection and can persist for 2 to 4 weeks in those who resolve acute infection.

Procedure and patient care

 • See inside front cover for Routine Blood Testing.

 • Fasting: no

 • Blood tube commonly used: red

 • Usually, a hepatitis profile that includes several HBV antigens and antibodies is performed.

 Abnormal findings

 Increased levels

- Hepatitis A

- Hepatitis B

- Hepatitis C

- Chronic carrier state, hepatitis B

-Chronic hepatitis B

-Hepatitis D

 -Hepatitis E

مواضيع ذات صلة

Direct Detection Methods for Bacillus and Similar Organisms

HIV drug resistance testing (HIV genotype)

herpes simplex (Herpesvirus types 1 and 2, Herpes simplex virus types 1 and 2 [HSV 1, HSV 2], Herpes genitalis)

Biomarkers of Nutritional Status

Malnutrition

hemoglobin (Hb, Hgb)

hematocrit (Hct, Packed red blood cell volume, Packed cell volume [PCV])

Helicobacter pylori testing (Anti–Helicobacter pylori antibody, Campylobacter-like organism [CLO] test, H. pylori stool antigen)

Nonculture Methods For The Identification Of Pathogenic Microorganisms

Heinz body preparation

Haptoglobin

Transthyretin (Prealbumin)