The HIV Viral Load

Updated July 5, 2013

The most important lab value for you to know, if you are taking HIV medicines, is the HIV viral load (also commonly called the HIV-1 RNA).  Unlike the CD4, which you want to be high, you want your viral load to be as low as possible--undetectable virus is what you are aiming for.  

Picture of HIV virus (green spiked ball) floating among red blood cells.
The less you have of these, the better!

When you first hear the words “viral load” you may feel confused about what this term means.  Wait a year.  Before you know it, the words viral load (and CD4 count) will become as comfortable as an old pair of slippers.  You will go to your health care clinic armed with a pen and notebook and demand to know what your latest counts are, so you can keep track of your HIV yourself.  About half of my patients ask for paper copies of their lab results.

How is the HIV viral load reported?

The viral load is reported as “copies/ml” or copies of virus in a milliliter.  Think of copies as particles.  You know how sometimes the sunlight coming through the window will let you see little dust particles suspended in the air?  The virus particles floating in your blood are actually smaller than these dust specks.

You will see an undetectable HIV viral load reported like one of these examples below: 
< 20 copies/ml (translated, less than 20 particles per drop of blood)
< 25 copies/ml (translated, less than 25 particles per drop of blood)
< 50 copies/ml (translated, less than 50 particles per drop of blood)
< 75 copies/ml (translated, less than 75 particles per drop of blood)
< 100 copies/ml (translated, less than 100 particles per drop of blood)
< 400 copies/ml (translated, less than 400 particles per drop of blood)
Undetectable is reported at different levels (<20, <25, <50, <75, <100, and <400) depending on the test your particular lab runs.  <20 is a very sensitive test.  A detectable viral load may range as high as more than 1,000,000.

Of note: There will be the words "reference range" printed below the actual results.  This will usually be written as follows:  Reference range: undetectable.  This means that a normal test result is "undetectable". There should not be HIV virus in the blood.  
  

So what exactly is the HIV viral load?  If you are not taking HIV medicines, the virus makes billions of copies of itself every single day.  The virus hangs out in the blood, spleen, and lymph nodes, and other body tissues. It is not possible to measure the amount of virus in your entire body, but it is possible to measure the amount of virus in a small sample of your blood.  The HIV viral load test takes a small sample of your blood and counts the number of particles (or copies of virus in this sample.  The blood sample is separated from the plasma, or yellowish liquid part of the blood from the actual blood cells (red blood cells, white blood cells, and platelets).  

The plasma is the part of the blood that is studied (see picture above).  Since the test measures particles of virus, the higher the number, the worse off you are.  You want the viral load to be low--unlike the CD4 count which you want to be high.  Remember it like this: do you want high virus in your blood--or low virus?  The lower the better.  If no virus is seen, this is called "undetectable" and this is best.  

There are several different types of test on the market--it doesn’t really matter which type is used--however, it is important to know if your lab has changed the viral load testing method it is using.  

It is always important to recheck test results when the results are not in line with what is expected.  If your viral load is always undetectable-- and nothing has changed with the way you take your HIV medicines--and then the viral load suddenly rises to more than 1000, repeat the test.  Do not make any decisions or change anything based on one result.  

The viral load, just like the CD4 count, can also be affected by whether or not you have a new bacterial or viral infection.  For instance, do you have a cold or a urinary tract infection?  Also, you should avoid having your viral load checked within one month of getting vaccinations.

Why is the HIV viral load test important?

HIV damages the immune system (specifically, it attacks the CD4 cell) and, untreated, leads to AIDS (a CD4 less than 200) and eventually death.  The virus, even in the early stages, can damage body organs and lead to one of many numerous complications.

If you are on medicine, you want to be sure the viral load is going downward or at undetectable.  And you want it to get to undetectable within six months or so.  For example, if you started antiviral medicines with a viral load of 350,000 and six months later your viral load is 85,000, it may seem to you like that’s a good thing--after all, the virus number is headed downward.  Not so.  By six months, your virus should be at or nearly undetectable.  Your medical provider will suspect that your HIV medicines are not working (failing) and send you for additional lab tests.  He/she will also question you about whether you are actually taking the antiviral medicines.  You will save yourself lots of time if you are honest with your medical provider.  It’s useless to run tests to see if the drugs are working if you know you have been skipping your HIV medicine doses. 


Another big reason to have undetectable HIV virus levels is so that you are not easily able to transmit HIV. If you have high amounts of HIV in your blood, it is more likely that you may give your sex partner HIV.  If your virus is at undetectable, it is hard to infect someone else.

The HIV viral load gives you and your medical provider lots of information.  Are your medicines working like they should?  Are the medicines failing? 

Another time the viral load test may be used is immediately after getting infected with HIV.  Remember, the HIV antibody test, the ELISA, takes several weeks to turn positive after the virus enters the body.  In some cases, a person who is feeling sick, and goes to the emergency room with flu-like symptoms, the medical provider may suspect HIV infection.  The provider can order an HIV viral load test as well as the ELISA test.  Most likely, the HIV viral load test will show high amounts of virus and the ELISA test will still be negative.  

The amount of HIV virus in the blood will also factor into the decision to start HIV medicines.  However, the CD4 count is a more important factor in this decision.  For example, if your CD4 is 950, but your viral load is 50,000 (considered high), your medical provider may still want you to wait until your CD4 count drops despite this high amount of virus in your blood.  

abysebata.cwahi.net

A viral load in the hundreds of thousands ("six-figures", I call it) may give you a clue as to how fast your virus will lead you to an AIDS diagnosis. Think of the viral load like a crystal ball as it can tell your fortune.  Go to a fortune teller who uses one of those crystal balls. (Do they still use these?) The woman waves her thin long fingers over the ball and says you are going to meet a handsome stranger and this person will be the love of your life and you will have many long and happy years together or you are going to lose all your money and will get sick within the next 5 years.  A viral load that is in the tens of thousands or hundreds of thousands predicts a bad future of illness; it's time to act quickly to start HIV medicines.  A low viral load predicts good health and much less chance of serious illness.  



Look at these two  scenarios: 

Scenario 1:

Bob’s CD4 count at diagnosis is 840.  During the first year after diagnosis, his viral load is consistently from 1000 to 9000.  We can sort of predict that Bob’s body may hold the virus in check for several more years, keeping him off HIV medicines.  I say sort of predict because we cannot predict with 100% sureness--we can only make an educated guess.

Scenario 2:

Jack started with the same CD4 count as Bob’s--840.  His viral load the first year after diagnosis is alway more than 100,000 (six-figures).  We can “sort of predict” that Jack will develop AIDS or a sickness related to AIDS much earlier than Bob.

Whether you are on medicines or not, you will need to get your viral load checked every 3-4 months.  Your viral load may also be checked 4 to 6 weeks after starting new antiviral medications.  

Just like people get upset when their CD4 count decreases, people on HIV medicines get even more upset when they see their viral load increasing.  By 3-6 months or so on medicines, most people will be at or close to undetectable viral load.  So it’s understandable that you might get worried if your virus goes from undetectable to 350 at your next check-up.  To your medical provider, this change may be insignificant.  It’s a low level of virus.  Anything less than 1000 is considered low.  If your virus amount increases to 950 by the next time it’s checked, your provider will be more concerned.  After all, now you have a trend of moving upward.  He/she will probably question you about whether you’re missing any doses of antiviral medicine.  If not, don’t worry.  Just go on taking care of yourself the same way you’ve always done.  If, on the other hand, you are missing medicine doses, you may be showing signs of medicine resistance.  It’s important to nip this problem in the bud right now.  If you’re missing your medicines, figure out what the problem is, and FIX IT.  I will talk more about resistance in later blogs.  

Usually, a high CD4 goes hand in hand with a low viral load and vice versa.  A high viral load goes along with a low CD4.  It just makes sense that it would be this way, doesn’t it?  More virus, more immune system destruction.  As the viral load goes down, the CD4 should move up, but this is not always the case.  Age, other illnesses you may have, and even some medicines may keep your CD4 from going up quickly.  AZT (also called Retrovir or Zidovudine) and D4T (also called stavudine or Zerit) are famous for causing bone marrow suppression which will hold down your CD4 count.

Undetectable virus is usually below 25-50, depending on the test that is used. If you are on medicines and your viral load was undetectable, then increases to the 100-400 range, do not worry, as this type of "blip" is common.  Again, as long as you are taking your medicine correctly, there is probably nothing to worry about.  Now, if the viral load continues to rise, that is a problem.  

In some cases, people are never able to achieve undetectable, but they maintain a viral load less than 200.  This is okay too, as long as the person is taking the HIV medicine correctly.  If the viral load is always above 200, despite taking the medicines correctly, more testing may be needed. 

The viral load will always be checked after diagnosis, then every 3-4 months until HIV medicines are started.  If HIV medicines are started, a viral load may be checked within a month or so of starting the medicines, then 2-4 weeks after beginning taking the HIV medicines (some providers may wait up to 8 weeks).  The viral load is then checked every 4-8 weeks until the person becomes undetectable.  After getting to undetectable, the viral load will probably be checked every 3-4 months.  If the person has been undetectable (or nearly so) for 2-3 years, the viral load may be checked every 6 months.  This same schedule should be followed if the person has any HIV medicine changes.  

The HIV viral load test may also be known as:

1. HIV Nucleic Acid Amplification Test or the HIV NAAT or NAT 
2. HIV PCR test
3. Quantitative Plasma RNA test
4. HIV Quantification.   

From: Guidelines for the Use of Antiretroviral Agents in HIV-1 Infected Adults and Adolescents, January 10, 2011.

Lab Tests Online downloaded 7/3/13.

Please feel free to post a comment or a question about HIV.  Thanks for reading!