The first set of lab tests ideally is done shortly after you find out you have HIV, and the results establish a starting point or "baseline." Future tests will let you know how far from this baseline you have moved. This can help you tell how fast or slow the disease is moving and indicate whether treatments are working.
Most labs include a "normal" range (high and low values) when they report test results. The most important results are the ones that fall outside these normal ranges. Test results often go up and down over time so don't worry about small changes. Instead look for overall trends.
What follows are descriptions of the most common tests:
CD4 cells (also known as CD4+ T cells) are white blood cells that fight infection. CD4 cell count is an indicator of immune function in patients living with HIV and one of the key determinants for the need of opportunistic infection (OI) prophylaxis. CD4 cell counts are obtained from bloodwork as part of laboratory monitoring for HIV infection.
CD4+ cell counts are usually measured when you are diagnosed with HIV (at baseline), every 3 to 6 months during first 2 years or until your CD4 count increases above 300 cells/mm 3 . Otherwise your CD4+ cell count may be measured every 12 months. Most people who are on HIV treatment can expect an average increase of about 50-100 cells/mm 3 a year. Patients who initiate therapy with a low CD4 count or at an older age may not have the same increase in their CD4 count despite virologic suppression.
There are multiple factors that affect your CD4 count. Taking your medication is one way to keep your count high but medications or acute infections are among the things that could affect the CD4 count. If you are responding well to your medications, you may need less frequent testing going forward.
HIV viral load tests measure the amount of HIV in the blood. Lower levels are better than higher levels. The main goal of HIV drugs is to reduce the HIV viral load to an "undetectable" level, meaning that the HIV RNA is below the level that the test is able to count.
The lower limit of HIV RNA detection depends on the test used--some go down to 50 copies/ml, while other go as low as 20. High viral loads are linked to faster disease progression. Reducing the viral load to "undetectable" levels slows or stops disease progression and prevents HIV transmission to sex partners. Treatment for HIV suppresses the virus but does not eliminate it. Even if HIV levels are not detectable in the bloodstream, HIV is still in the body and will rebound to detectable if the HIV medicines are stopped.
The lower your viral load, the better.
CD4 counts and HIV viral load tests are usually done when you first see a medical provider and about every 3 months afterwards. Results tell whether the HIV medications are working well; and for people who have chosen to delay taking medicines, they can help you and your provider monitor your health and decide how urgent it is for you to start taking HIV drugs or medicines to prevent infections (more on this in Treatment Decisions).
This test determines whether the particular virus in your body is resistant to HIV medications.
HIV reproduces rapidly and, as the virus makes copies of itself, small changes (or mutations) sometimes result. These changes can lead to different HIV strains, particularly if the person is taking (or has taken) HIV medicines but the HIV virus is not completely controlled or suppressed. If a strain that is resistant to your HIV drugs develops, the virus will be able to grow even though you are on medication. Your viral load will start to rise. The resistant virus soon will become the most common strain in your body. If this occurs, your provider may order a resistance test to check for mutations in the HIV virus.
A person can be infected with a drug resistant strain of HIV if the infection was from an individual with resistant virus. For this reason, an HIV resistance test is recommended for all people as soon as they are diagnosed with HIV.
Therefore, resistance testing is performed upon diagnosis of HIV and if a medication regimen is no longer keeping the viral load suppressed.
Pop question: True or false. Resistance refers to certain strains of the HIV virus that do not respond to HIV drugs.
Pop question: True or false. Resistance refers to certain strains of the HIV virus that do not respond to HIV drugs.
Answer: TRUE. Resistance refers to certain strains of the HIV virus that do not respond to HIV drugs. This happens when the virus undergoes a change that makes the HIV drugs no longer effective.
This test looks at the different cells in your blood, including red blood cells, white blood cells, and platelets.
These tests are usually done every 3 to 6 months, unless your lab values are fluctuating a lot, or you have symptoms of HIV disease. Then the tests may be done more often.
Chemistry tests examine the levels of different elements and waste products in the blood and help determine how well different organs are functioning. Usually, the tests are divided into two panels:
Blood chemistry tests are usually done every 3 to 6 months. It is important to have these done at baseline and while you are on HIV medications to make sure the medications are safe for your kidneys and liver.
The level of certain fats in the blood can give clues to your risk of heart disease. Cholesterol and triglycerides are important for health, but too much of them in the blood can cause fatty deposits to form in the arteries. This increases the chances of a heart attack. Too much triglyceride can also lead to pancreatitis, a serious inflammation of the pancreas. High cholesterol and high triglycerides can occur in people living with HIV. They can also be a side effect of some of the older HIV medications.
Cholesterol is measured by three different tests:
These tests are usually done at least once a year, and more often if your levels are high or you require medication to control triglyceride and cholesterol levels. Your provider may want the lipid panel to be done while you are fasting, which means nothing to eat or drink (except water) after midnight the night before the test. This gives the most accurate evaluation of the cholesterol and triglycerides in the blood. Be sure to ask your provider if the blood tests are recommended to be done fasting.
TB is short for tuberculosis, an infection usually spread by breathing in air that has been contaminated by someone with TB of the lungs. Most people who are exposed to TB don't get sick from it-the bacteria can live in the body for a long time without causing disease. But some people who carry the bacteria develop tuberculosis disease, and this is more likely if the immune system is weakened.
There are two types of tests to determine whether people are carrying the TB bacteria. One is the TB skin test (also known as PPD), which requires the person to return to the clinic 2-3 days after the skin test is placed for the test to be interpreted. The other is a blood test called an interferon-gamma release assay (IGRA) (QuantiFERON and TSpotTB are two examples of IGRA blood tests).
If a person tests positive for carrying the TB bacteria in their body, tests are done to determine whether it is currently causing infection of the lungs (which is contagious). Anyone with active TB should get an effective combination of medications to be cured. If, however, there is no active infection, antibiotics can be used to prevent trouble in the future. In this setting antibiotics are given for 3-9 months.
If you got infected with HIV from unprotected sex, there is a chance you may have become infected with other sexually transmitted diseases, too. These include syphilis, gonorrhea, and chlamydia. Hepatitis B and hepatitis C can be sexually transmitted as well, particularly among men who have sex with men.
Infections of syphilis, gonorrhea, and chlamydia can occur in the throat, penis, vagina, and rectum. The bacteria that cause syphilis and gonorrhea can also spread through the blood to other parts of your body. Having one of these other diseases can make your HIV worse. They can also make you 2 to 5 times more likely to pass HIV along to a sexual partner. Syphilis, for example, can cause open sores on your genitals, which allows easy passage of HIV from you to your partner.
Tests for STDs, hepatitis B, and hepatitis C should be done at baseline. STD tests should be repeated at least once a year if you are sexually active and have had more than one sex partner since your last clinic visit. Men who have sex with men who have multiple or anonymous sex partners are recommended to be screened every 3-6 months, and this is a good idea for anyone with new partners.
Your liver is an organ that processes almost everything you put into your body, including medications. Viruses can infect and irritate the liver causing damage, scarring, and possibly liver failure. The three most common viruses that can infect the liver are hepatitis A, hepatitis B, and hepatitis C.
Find websites on more specific topics, such as opportunistic infections, travel health, and more.
