Lab Tests And Why They Are Important
As part of your HIV care, your provider will order several laboratory tests. The results of these lab tests, along with your physical exam and other information you provide, will help you and your provider work together to develop the best plan to manage your HIV care so that you can get the virus under control, protect your health, and reduce the chance that you will pass the virus to others.
Your healthcare provider will repeat some of these tests as part of your ongoing HIV care to continue to assess your health and how well your HIV treatment is working.
The lab tests may include:
- CD4 Percentage: This measures how many of your white blood cells are actually CD4 cells. This measurement is more stable than CD4 counts over a long period of time, but, for most people, the CD4 count remains a more reliable measure of how well your immune system is working than the CD4 percentage.Why its important: This measurement is less likely to vary in between blood tests than CD4 counts .
- Complete Blood Count : This is a measure of the concentration of red blood cells, white blood cells, and platelets in a sample of your blood.Why its important: A CBC is one of the most commonly ordered blood tests. It can reveal infections, anemia , and other medical issues.
Topics
What Is Hepatitis C
Hepatitis C is a liver infection caused by the hepatitis C virus . The abbreviation HCV can stand for either the virus or the infection it causes.
HCV can be either a short-term or a long-term illness:
- Acute HCV occurs within 6 months after exposure. In most people, acute HCV becomes chronic HCV.
- Chronic HCV can last a lifetime. Without treatment, chronic HCV can cause liver cancer or severe liver damage that can lead to liver failure.
- HCV is a contagious infection that can spread from person to person.
Is This A Take
This is not a rapid, take-home HIV test. Instead, our at-home collection kit comes with the materials you need to collect a small sample of blood at home , and send that sample to a lab for testing.
A few weeks after being infected with HIV, you may develop flu-like symptoms such as:
- -Fever
- -Swollen lymph nodes
- -Rash
- -Tiredness
These symptoms usually disappear within a week to a month. You may have no other symptoms for many years.
If left untreated, HIV will continue to affect your immune system and lead to AIDS . Symptoms of AIDS include:
- -Extreme, unexplained tiredness
- -Prolonged shaking chills or fever
- -Prolonged swelling of lymph nodes
- -Chronic diarrhea
- -Unusual infections
- -Are sexually active and between the ages of 18 and 65
- -Are a man who has sex with men
- -Have new or multiple sex partners
- -Have had unprotected sex with someone at high-risk of HIV
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Hiv Transmission In Drug Users
For people who inject drugs, estimates of the risk of transmission from a contaminated needle range from 0.3% to 4.0%, with several of these estimates falling in the range of 0.7% to 0.8%. Sharing ancillary injecting equipment, such as filters or cookers, has been shown to increase the risk of transmission, even in the absence of sharing needles and syringes. Other factors that have been shown to increase the risk of HIV transmission for injection drug users include: unsafe locations, type of drug and frequency of drug injection. Non-injection drug users are also at risk of HIV infection. Drug use often alters sexual behaviours by increasing risk taking. As well, several drugs have been reported to be independent risk factors of HIV transmission.
Types Of Hiv Testing Services
4.5.1 Standard
The majority of healthcare venues carry out “standard” HIV testing. This means a tube of blood is collected in the clinic, hospital or physician’s office and sent to the medical laboratory along with a requisition ordering an HIV test. Standard testing can be done in any type of setting . Test results are generally available within one week.
4.5.2 Point-of-Care or rapid testing
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Emergency Intervention Disclosure Act
The following information about the Emergency Intervention Disclosure Act is provided for information purposes and guidance only. If there is a conflict between this website and the Emergency Intervention Disclosure Act or the Emergency Intervention Disclosure Regulation, the Act and Regulation prevail.
The Emergency Intervention Disclosure Act permits individuals, to apply to the court for an order to have another person tested for Hepatitis B, Hepatitis C or HIV if they have come into contact with a persons bodily substance in any of the following circumstances:
- While providing emergency health services.
- While performing their duties as a fire fighter, emergency medical assistant or police or other peace officer.
- When they have reason to believe that they have been the victim of an alleged offence under the Criminal Code and have reported the matter to a law enforcement agency.
The purpose of the Testing Order is to provide information to the exposed individual about the test results of the source individual, which may assist the exposed individual and their physician in managing the possible consequences of the exposure. There are strict timelines to the Testing Order process, please review the information below and Frequently Asked Questions section for additional information.
False Reactive Test Results
What if I have a false reactive test result?
Every donation given to Canadian Blood Services is tested for infectious diseases caused by the hepatitis viruses B and C, HIV, syphilis and another uncommon virus called HTLV .
A false reactive test result means your initial screening test was reactivein other words, suggested the presence of something that would prevent you from donating bloodand a more precise follow-up test was negative. Almost all false reactive results occur because of interference with a test and are not necessarily due to testing positive for an infection.
FAQS
How does Canadian Blood Services test blood?
We follow a two-stage testing method that is used in laboratories worldwide. In the first stage, a sensitive screening test looks for the possible presence of infection. If the screening test shows no reaction, the blood is considered free of infection and no further testing is done. However, if the screening test is reactive, further testing is done to sort out whether the reactive result was due to an infection in the blood or interference with the test. The second test identifies markers in the blood that are found only when infection is present.
Do I need to go to my doctor for repeat testing?
Yes. Repeat testing should be discussed with your doctor because he/she is in the best position to offer you personal medical advice.
Do my partner, children, or friends need to worry if I’ve had a false reactive result?
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Discussing Screening Results With Clients
The medical personnel who ordered or arranged the screening test, not counselors, usually explain the results. Hepatitis screening should be part of the intake physical examination in an opioid treatment program, and medical personnel may report the results. However, the client may want to discuss the results with the counselor or ask the counselor questions.
Anxiety might interfere with some clients ability to comprehend or retain information, which might need to be repeated.
Suggestions for conversations with clients when the test results are negative include the following:
- Explain results clearly and simply: So the HCV screening result was negative? This means that, as of 6 months ago, you did not have .
- Emphasize that a negative result to an HCV test does not indicate to and that the client should take precautions to avoid . If a relapse to drug use occurs, advise clients to avoid sharing any drug paraphernalia or equipment. Specify that this includes cookers, cotton, water, needles, syringes, pipes, and straws.
- Emphasize the importance of getting HAV and HBV vaccinations. Provide information about the availability of low- or no-cost vaccinations.
Clients whose screening test results are positive for will need additional tests and examinationsusually with doctors who specialize in diseases of the liver to get accurate diagnoses and to determine their health status and the extent of liver damage. These tests are described in .
Hepatitis C Virus Antibody Testing
Hepatitis C Total Antibody Serology
This investigation is used as a screening test to determine current and a past infection with Hepatitis C. This test is carried out on site.
If the initial test for Hepatitis C Antibody is reactive a qualitative PCR test will be carried out . A second specimen of blood will also be requested it is important that the laboratory receives this second sample.
Lorenzo item name: Hepatitis C Ab level, blood
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Dried Blood Spot Collection For Hepatitis C And Hiv Testing In Canada
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Dried blood spot collection is a promising approach to hepatitis C and HIV testing that can reach people who might not access traditional health services. Using this method, a sample of blood droplets is collected on a filter paper and then dried for transportation to a laboratory where standard hepatitis C and/or HIV testing is performed. The ease of sample collection and the stability of the collected sample make DBS collection a useful tool. This approach is not yet widely used in Canada for hepatitis C and HIV testing, but it may become more widely available in the coming years as it has the potential to complement existing testing options. This article will explore what DBS testing is, the advantages of DBS testing and its use in Canada.
Should People With Hiv Get Tested For Hcv
Every person who has HIV should get tested for HCV. Usually, a person will first get an HCV antibody test. This test checks for HCV antibodies in the blood. HCV antibodies are disease-fighting proteins that the body produces in response to HCV infection.
A positive result on an HCV antibody test means that the person has been exposed to HCV at some point in their life. However, a positive antibody test does not necessarily mean the person has HCV. For this reason, a positive result on an HCV antibody test must be confirmed by a second test. This follow-up test checks to see if HCV is present in the personâs blood. A positive result on this test confirms that a person has HCV.
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Enzyme Immunoassays For Detection Of Hepatitis C Antibody
The HCV Ab test is used for initial screening for hepatitis C. The test is performed by enzyme immunoassays , which detect the presence of hepatitis C antibodies in serum. The result of the test is reported as positive or negative. Third-generation EIAs have a sensitivity/specificity of approximately 99%. However, the presence of HCV Ab does not indicate whether the infection is acute, chronic, or resolved. A positive antibody test result should be followed up with an HCV RNA test to confirm that viremia is present.
Time For Processing Hcv Ab Test Results
The turnaround time for 3rd-generation EIAs is at least 1 day. Many labs do not perform the tests on site and must send specimens to another lab for processing, which may further increase the turnaround time.
A point-of-care test is also available. The OraQuick® HCV Rapid Antibody Test is an FDA-approved test that can be performed with a fingerstick . It is also a CLIA-waived test and therefore can be used in clinic offices and outreach facilities. Results are reported as reactive or nonreactive within 20 minutes. Just as for the standard HCV Ab test done in the lab, a positive OraQuick® test must be confirmed by an HCV RNA test. The sensitivity and specificity of the test is similar to that of the laboratory-based assays.
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Hepatitis B Antibody/antigen Testing
Note a full marker antibody and antigen serology repertoire is available.
Hepatitis B Surface Antigen
This investigation is used as a screening test to determine infectivity with Hepatitis B.
This test is carried out on site.
Lorenzo item name: Hepatitis B surface Ag screen, blood
Hepatitis B Total Core Antibody
This test is used to determine past infection with Hepatitis B it is also used along with the HBSAg assay to determine acute/current Hepatitis B infection.
This test is carried out on site.
Lorenzo item name: Hepatitis B core Ab screen, blood
Hepatitis B Surface Antibody
This test is carried out on site. It is primarily used to determine immune status following a vaccination course, but can be used with the Hepatitis B Total core antibody to determine natural past infection with Hepatitis B.
Lorenzo item name: Hepatitis B surface Ab level
Hiv Testing Types And Lab Technologies
This chapter provides information regarding available testing technologies, approaches to testing and interpretation of results. There are many different types of HIV screening tests that are licensed for use in Canada and can vary by jurisdiction. For questions or information specific to your province or territory please contact your local Public Health laboratory.
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Terms And Technologies Used In Hiv Testing
This section provides detailed definitions and descriptions of the terms and technologies used in HIV testing.
4.2.1 Algorithms
Algorithms for HIV testing have been developed to ensure optimal sensitivity while preserving specificity by confirming reactive results as antibody-positive. The test sequence starts with the most sensitive screening test to identify all those with antibodies. A confirmatory assay is then performed only on the samples that tested reactive/positive on the initial screening test. This ensures that the screen test reaction is due to detection of HIV antibodies rather than a non-specific reaction. In the case of indeterminate or inconclusive results, additional supplementary testing may be necessary to determine if someone is infected with HIV. Each laboratory develops and validates its own algorithm to ensure that it provides the most accurate results possible. The positive predictive value and negative predictive value of a validated algorithm are close to 100%.
A typical laboratory testing algorithm follows:
Figure 3: Laboratory Testing Algorithm
A typical laboratory testing algorithm starts by screening with an enzyme immune assay test. If the EIA is non-reactive, then no HIV infection is present and no further testing is done.
If the initial EIA is reactive, then the EIA test should be repeated two additional times. If neither of the additional EIA tests is reactive, then the test is considered non-reactive, with no evidence of HIV infection.
Can Hcv Infection Be Prevented
The best protection against HCV is to never inject drugs. If you do inject drugs, always use new, sterile needles, and do not reuse or share needles, syringes, or other injection drug equipment.
People, including people with HIV, can also take the following steps to reduce their risk of HCV infection:
- Do not share toothbrushes, razors, or other personal items that may come in contact with another personâs blood.
- If you get a tattoo or body piercing, make sure the instruments used are sterile.
- Use condoms during sex. The risk of HCV infection through sexual contact is low, but the risk increases in people with HIV. Condoms also reduce the risk of HIV transmission and infection with other sexually transmitted diseases, such as gonorrhea and syphilis.
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Appendix D: Natural History Of Hiv Infection
Human immunodeficiency virus is a retrovirus that infects the cells of the immune system. It is transmitted via exposure to body fluids that contain lymphocytes or free infectious viral particles . The routes of infection are: unprotected sexual intercourse, sharing of injection-drug use equipment and from an HIV-infected mother to her unborn child. Although rare, HIV can also be transmitted through an occupational exposure such as a needlestick injury or other event where blood to blood exposure could occur. All blood and blood products used in Canadian healthcare settings now undergo extensive screening for HIV prior to use, so new infections related to their use have been virtually eliminated .
The virus can enter the body through unprotected mucous membranes where cells may become infected with HIV . The presence of a sexually transmitted infection can enhance HIV transmission because of lesions and/or an increased number of lymphocytes. Using a needle contaminated with HIV-infected blood deposits the virus directly into the blood system, where infection of lymphocytes will occur. Transmission from mother to child can take place in utero, during delivery through exposure to the mother’s blood or vaginal secretions, and through breast milk . Seroconversion occurs when an individual changes from being HIV antibody negative to HIV antibody positive.
Dbs For Hiv And Viral Hepatitis Molecular Testing To Detect Viral Replication Therapeutic Response And Virologic Theray Failure
The detection of nucleic acids on DBS also finds a strong clinical indication in the diagnosis of infections transmitted from mother to child. Regarding HIV diagnosis, the presence of maternal antibodies in infants makes serological tests ineffective until at least 1 year of age. Molecular diagnosis of HIV infection on DBS has been shown to be effective and is routinely used in clinical practice for this indication. DBS sampling is finally useful for specialized tests such as HIV resistance genotyping, and antiretroviral dosages . It should be noted that although the clinical relevance of HIV resistance genotyping on DBS is indisputable, it nevertheless faces the difficulty of molecular genotyping on DBS, at the threshold defining the therapeutic failure .
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What Is The Connection Between Hiv And Hcv
Because both HIV and HCV can spread in blood, a major risk factor for both HIV and HCV infection is injection drug use. Sharing needles or other drug injection equipment increases the risk of contact with HIV- or HCV-infected blood.
According to the Centers for Disease Control and Prevention , approximately 21% of people with HIV in the United States also have HCV. Infection with both HIV and HCV is called HIV/HCV coinfection.
In people with HIV/HCV coinfection, HIV may cause chronic HCV to advance faster. Whether HCV causes HIV to advance faster is unclear.