Understanding Of Lab Tests Results
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Question 1 What Is The Clinical Indication For Hepatitis B Surface Antibody Quantitation
Hepatitis B surface antibody quantitation is used to determine hepatitis B immune status, ie, to determine if the patient has developed immunity against the hepatitis B virus. Such immunity may develop following exposure to the hepatitis B virus or its vaccine.
Patients at higher risk of exposure to the virus include:
- Infants born to infected mothers
- Sex partners of infected persons
- People with more than 1 sex partner in the last 6 months
- People with a history of sexually transmitted infection
- Men who have sex with men
- Injection drug users
- Household contacts of an infected person
- Healthcare and safety workers who have contact with blood and body fluids
- People who have lived or traveled in an area in which hepatitis B is common
- People who live or work in a prison
Testing is not recommended routinely following vaccination. It is advised only for people whose subsequent clinical management depends on knowledge of their immune status. These people include:
- Chronic hemodialysis patients
- Immunocompromised people, including those with HIV infection, hematopoietic stem-cell transplant recipients, and people receiving chemotherapy
- Infants born to women who test positive for the hepatitis B surface antigen
- Sex partners of people who test positive for the hepatitis B surface antigen
- Healthcare and public safety workers who have contact with blood or body fluids
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Core Antigen And Antibody
Hepatitis B core antigen
The hepatitis B core antigen is part of the nucleocapsid within HBV it is not routinely measured in clinical practice however, the body produces a corresponding antibody to this antigen called hepatitis B core antibody , which is clinically relevant.
Antibody to Hepatitis core antigen :
Anti-HBc is the antibody produced by the host in response to HBcAg depending on which immunoglobulin type is present indicates the time frame since infection. The presence of anti-HBc IgM indicates recent infection within the last six months.1 Over time, IgM is gradually replaced by anti-HBc IgG therefore, anti-HBc is seen in patients with resolved infection and those with chronic infection.1 This is shown in Figure 2, as anti-HBc IgM acutely rises and falls, whilst total anti-HBc rises and plateaus as IgG production predominates.6
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Proportions Of Lf And Aclf In Dep Patients
The median APRI score in the DEP group was 1.66 , which was remarkably higher than that in the HBeAg+/anti-HBe- and HBeAg-/anti-HBe+ groups . The median FIB-4 score in the DEP group was noticeably higher than that in the HBeAg+/anti-HBe- group .
Among cases in the I-AP, the median APRI score in the DEP group was markedly higher than that in the HBeAg+/anti-HBe- and HBeAg-/anti-HBe+ groups . The median FIB-4 score in the DEP group in the I-AP was higher than that in the HBeAg+/anti-HBe- group , while we did not identify a significant difference in FIB-4 score between the DEP and HBeAg-/anti-HBe+ groups.
The proportions of cirrhosis and decompensated cirrhosis in the DEP group were noticeably higher than those in the other two groups . Furthermore, the proportion of ACLF in the DEP group was higher than that in the HBeAg+/anti-HBe- group and HBeAg-/anti-HBe+ group .
In the I-AP, the proportions of cirrhosis , decompensated cirrhosis , and ACLF in the DEP group were greater than those in the HBeAg+/anti-HBe- group , while they were not significantly different between the DEP group and the HBeAg-/anti-HBe+ group .
What Is The Difference Between Hepatitis B Surface Antibody And Antigen
An antigen is a substance that induces antibody production. Hepatitis B surface antigen is a protein on the surface of hepatitis B virus.
Hepatitis B surface antibodies are produced by the bodys immune system in response to HBsAg. The presence of adequate hepatitis B surface antibodies in the blood indicates protection against hepatitis B virus infection.
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Other Reported Adverse Events And Conditions
While serious events and chronic illnesses such as chronic fatigue syndrome, multiple sclerosis, Guillain-Barré syndrome, rheumatoid arthritis and sudden infant death syndrome have been alleged or reported following HB vaccination, no evidence of a causal association has been demonstrated in a number of studies.
Concurrent Administration Of Vaccines
HB-containing vaccines may be administered concomitantly with other vaccines or with HBIg. Different injection sites and separate needles and syringes must be used for concurrent parenteral injections.
Refer to Timing of Vaccine Administration in Part 1 for additional information about concurrent administration of vaccines.
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What Is The Hbeag Test
The HBeAg test is used to detect the presence of the active hepatitis B virus. If a person is infected with this virus, the level of HBeAg and also HBsAg will be high. The presence of HBeAg in the blood is associated with hepatitis B virus infectivity, the number of infectious virions present in the body, and the presence of HBV core antigen in the infected liver cells.
Persons With Chronic Diseases
Refer to Immunization of Persons with Chronic Diseases in Part 3 for additional general information about vaccination of people with chronic diseases.
Chronic renal disease and patients on dialysis
People with chronic renal disease may respond sub-optimally to HB vaccine and experience more rapid decline of anti-HBs titres, and are therefore recommended immunization with a higher vaccine dose. Individuals undergoing chronic dialysis are also at increased risk for HB infection. In people with chronic renal disease anti-HBs titre should be evaluated annually and booster doses using a higher vaccine dose should be given as necessary.
People with conditions such as autism spectrum disorders or demyelinating disorders should receive all routinely recommended immunizations, including HB-containing vaccine.
Chronic liver disease
HB immunization is recommended for non-immune persons with chronic liver disease, including those infected with hepatitis C, because they are at risk of more severe disease if infection occurs. Vaccination should be completed early in the course of the disease, as the immune response to vaccine is suboptimal in advanced liver disease. Post-immunization serologic testing may be used to confirm vaccine response.
Non-malignant hematologic disorders
Persons with bleeding disorders and other people receiving repeated infusions of blood or blood products are considered to be at higher risk of contracting HB and should be offered HB vaccine.
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Types Of Hbeag Variants
The anti-viral effect of anti-HBe immunity may explain the frequent emergence of HBeAg variants in patients with anti-HBe. Since HBeAg expression is not essential for virus replication, the simplest way for the virus to evade the anti-HBe immunity is to switch off HBeAg expression altogether. The so-called precore mutants are the first discovered major immune escape mutants of HBV. These mutants are characterized by a G1896A nonsense mutation in the precore region that truncates the precore/core protein into a 28-aa peptide . Other nonsense and frameshift mutations inside the precore region have also been found, although less frequently. Point mutations of the precore ATG codon have also been observed, which prevent initiation of translation. We recently found that triple mutation at the 5, -3, and 2 positions of the precore ATG codon, as occasionally found in some South African strains of HBV, greatly reduced translation efficiency . The selective disruption of HBeAg expression through mutations affecting the precore region rather than the core gene can be easily understood in terms of the indispensable role of core protein for viral replication.
Clinical Information Discusses Physiology Pathophysiology And General Clinical Aspects As They Relate To A Laboratory Test
Hepatitis B e antigen is a small polypeptide that exists in a free form in the serum of individuals during the early phase of hepatitis B infection, soon after hepatitis B surface antigen becomes detectable. Serum levels of both HBeAg and HBsAg rise rapidly during the period of viral replication. The presence of HBeAg in serum correlates with hepatitis B virus infectivity, the number of infectious virions, and the presence of HBV core antigen in the infected hepatocytes.
During recovery from acute hepatitis B, HBeAg level declines and becomes undetectable in the serum, while hepatitis B e antibody appears and becomes detectable in the serum. Anti-HBe usually remains detectable for many years after recovery from acute HBV infection.
In HBV carriers and patients with chronic hepatitis B, positive HBeAg results usually indicate presence of active HBV replication and high infectivity. A negative HBeAg result indicates very minimal or no HBV replication. Positive anti-HBe results usually indicate inactivity of the virus and low infectivity. Positive anti-HBe results in the presence of detectable HBV DNA in serum also indicate active viral replication in these patients.
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Hepatitis B Virus Antigens And Antibodies
The Structure of Hepatitis B Virus
The hepatitis B virus is a small DNA virus with unusual features similar to retroviruses, which is a prototype virus of the Hepadnaviridae family. HBV causes acute and chronic hepatitis in humans. The hepatitis B virus consists of an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. The virus is one of the smallest enveloped animal viruses with a virion diameter of 42 nm, and also named Dane particles. Dane particles contains both envelope and core.
The outer envelope contains embedded proteins which are involved in viral binding of susceptible cells. There are three types of proteins: small hepatitis surface proteins, middle hepatitis surface proteins and large hepatitis surface proteins, they are totally composed of hepatitis B surface proteins. The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity.
There are three types of Hepatitis B Virus particles in infectious serum by electron microscopy, Dane particles, filamentous particles and spherical particles. Except for Dane particles , there also exist pleomorphic forms, as filamentous particles and spherical particles .
Hepatitis B Virus Antigens
Hepatitis B core antigen-HBcAg
Hepatitis B e antigen-HBeAg
The X gene codes for HBxAg. The product of the X gene is hepatitis B x antigen . It may be involved in carcinogenesis.
Hepatitis B Virus Antibodies
Whats The Hepatitis B Titer Test Used For
A hepatitis B titer test measures antibodies in your blood to see if youre immune either due to vaccination or previous infection.
Hepatitis B is a viral infection that targets your liver. It can be transmitted by coming into contact with the bodily fluids of an infected person. A person with the virus can also infect their child during birth.
Hepatitis B can develop into a chronic infection. Chronic infection occurs when your body cant fight off the virus within six months. Chronic hepatitis B infections most commonly develop less than six years old, especially in infants.
Hepatitis B titer tests can be used to evaluate:
- whether a high-risk person is immune to hepatitis B
- whether hepatitis B immunoglobulin is needed after a needle prick
- men who have sex with men
- people born in countries with a hepatitis B prevalence greater than 2 percent
- people born in the United States not vaccinated as children and with parents born in regions with more than 8 percent hepatitis B prevalence
You may need your titer test results as proof of hepatitis B immunity in order to get into healthcare programs at many schools for example, the nursing program at Lone Star College. In the United States, employers are not allowed to withdraw a job offer if they learn you have hepatitis B.
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Discusses Conditions That May Cause Diagnostic Confusion Including Improper Specimen Collection And Handling Inappropriate Test Selection And Interfering Substances
Individuals who have received blood component therapies , plasma, or intravenous immunoglobulin infusion) in the previous 3 to 6 months may have false-positive hepatitis B surface antibody results due to passive transfer of anti-HBs present in these products.
Individuals possessing IgM anti-rubella virus may have falsely high results with the VITROS Anti-HBs quantitative test.
Anti-HBs levels from past hepatitis B or hepatitis B virus vaccination may fall below detectable levels over time.
A positive anti-HBs result does not exclude infection by another hepatitis virus.
Performance characteristics have not been established for the following specimen characteristics:
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Does Hepatitis B Show Up In Routine Blood Tests
Routine blood tests do not detect hepatitis B virus infection. Hepatitis B tests are specifically done if blood tests show abnormal liver function results, or if a person experiences symptoms or falls into the high-risk category for HBV infection.
A panel of HBV-specific blood tests are required to detect HBV infection.
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Some Core Promoter Mutants Are Impaired In Virion Secretion Due To Mutated Envelope Gene
Clones 4B and 4C are derived from the same patient and both displayed extremely high replication capacity due to the 1753/1762/1764/1766 quadruple mutation in the core promoter region . However, clone 4B secreted virus particles to culture medium very efficiently, while clone 4C was totally defective in virion secretion. It also failed to secrete HBsAg into culture supernatant despite its presence in cell lysate . Another high replicating core promoter mutant, clone 3.4, was impaired in virion secretion and displayed low HBsAg levels in both the cell lysate and culture supernatant . Extensive mapping experiments revealed an R169P mutation in the S gene of clone 4C as responsible for the block to the secretion of both viral and subviral particles . For clone 3.4, a G119E mutation in the S gene impaired virion secretion. This mutation apparently also impaired HBsAg recognition by the monoclonal antibody used for the commercial assay, since residue 119 is in the vicinity of the determinant, the dominant epitope in the S domain. Clone 4B actually contained a mutation capable of blocking virion secretion. However, presence of an M133T mutation in this clone overrides the I110M mutation and confers efficient virion secretion . Interestingly, the M133T mutation creates a consensus sequence for N-linked glycosylation , which may facilitate proper protein folding or assembly through the disulfide bonds.
|abolishes HBsAg secretion abolishes virion secretion|
Surface Antigen And Antibody
Hepatitis B surface antigen
The hepatitis B surface antigen is a protein found on the surface of HBV it is the firstserum to be detected following initial infection. Whilst it is the first antigen to appear, it is important to note, there is a window period of up to 200 days between the first exposure to HBV and the detection of HBsAg in the serum.2
HBsAgseroconversion is the development of antibodies against HBsAg it indicates the clearance of HBsAg and the resolution of infection.5 The presence of HBsAg always implies activeinfection, whilst persistence of HBsAg for more than six months indicates chronic infection.5
Antibody to Hepatitis B surface antigen
Anti-HBs is the antibody produced by the host in response to HBsAg . The presence of anti-HBs without HBsAg indicates two possible scenarios: either previous, cleared infection or vaccination against hepatitis B virus distinguishing between these two scenarios is possible with further serological testing. Anti-HBs remains in serum for life and indicates immunity to HBV.
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Persons With Inadequate Immunization Records
Evidence of long term protection against HB has only been demonstrated in individuals who have been vaccinated according to a recommended immunization schedule. Independent of their anti-HBs titres, children and adults lacking adequate documentation of immunization should be considered susceptible and started on an immunization schedule appropriate for their age and risk factors. Refer to Immunization of Persons with Inadequate Immunization Records in Part 3 for additional information.
Demographic Features Of Dep Cases And Prevalence Of Dep
Among C-HBVI cases, there were 165 DEP cases. After excluding 64 cases with HBeAg- and anti-HBe-negative, the remaining 2591 cases were assigned into 2 subgroups based on the results of a serology test: HBeAg+/anti-HBe- group and HBeAg-/anti-HBe+ group . Besides, 78 , 281 , and 363 cases in the I-AP were allocated to DEP, HBeAg+/anti-HBe-, and HBeAg-/anti-HBe+ groups, respectively . In total, 71.5% of the DEP cases were male, which was similar to the proportions of those who were in HBeAg+/anti-HBe- and HBeAg-/anti-HBe+ groups. DEP cases tended to be older than HBeAg+/anti-HBe- cases and were markedly younger than HBeAg-/anti-HBe+ cases .
Table 2 Demographic, Serological, and Clinical Features of DEP, HBeAg+/Anti-HBe-, and HBeAg-/Anti-HBe+ Cases with C-HBVI in the Immune-Active Phase
The prevalence of DEP was 8.0% and 4.4% among cases who aged < 45 and 45 years old, respectively . The prevalence of DEP among cases in the I-AP was 10.7% . Additionally, 56.9% of the cases in the DEP group were in the I-AP, which was similar to the proportion of cases in the HBeAg+/anti-HBe- group , while it was remarkably higher than that in the HBeAg-/anti-HBe+ group .
Table 3 Prevalence of DEP Among C-HBVI Cases
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