A regular part of your HIV health care involves having a sample of your blood drawn for testing in a laboratory. Laboratory tests are used to gauge your HIV disease progression and the overall health of your immune system. Common tests include viral load, CD4 cell count, complete blood count, blood chemistry tests (including liver function tests), and blood fat and sugar tests (lipid tests).

When you are first diagnosed as HIV+ or when you first start taking HIV drugs (treatment), you should get “baseline” tests that give a picture of your health at that moment. Later tests can be compared against these results to see how things are going, and if they are changing. Most monitoring tests should be done every three to six months, or as often as your doctor recommends.

Because results from different laboratories can vary, it’s a good idea to have your tests done at the same lab each time (you can ask your doctor if he or she knows if the same lab will be used every time). If you get an unexpected result on one test, your doctor will probably want you to get a second test to see if it confirms those results. Don’t worry too much about a single unexpected result—usually trends over time are more important. The ranges listed below are general and may not be exactly the same range as your lab, so look at your lab report for the normal range they use.

Viral load tests measure the amount of HIV in your blood. Your CD4 cell count measures how many CD4 cells are in your blood, reflecting the health of your immune system. Your doctor will usually look at the results of both these tests together, to get an idea of whether your HIV disease is progressing and whether your treatment is working.

Blood is made up of various types of cells and liquid. The complete blood count (CBC) is an inventory of all the different cells. CBCs are important because some HIV drugs can cause low red or white blood cell counts.

• Red blood cells (erythrocytes)
  These cells carry oxygen to all the cells of the body. Oxygen, which you take into your body through your respiratory system when you inhale, is vital for cells to live. A typical red blood cell count for women is 4-5.5 million red blood cells. Hematocrit and hemoglobin tests are measures of how well red blood cells carry oxygen. A normal hematocrit for women is 35-46 percent and a normal hemoglobin level is 12-16. Women normally have lower levels of red blood cells than men because they lose blood through menstruation.
• White blood cells (leukocytes)
  These cells carry out the body’s immune responses. A normal total white blood cell count is 4,000-11,000. The “differential” reports the proportions or relative amounts of different types of white blood cells:

• Neutrophils
  These white blood cells fight infections. A normal neutrophil proportion is about 50-70 percent. When your neutrophil count falls below about 500-750 cells (a condition called neutropenia), you are more likely to get bacterial infections.
• Lymphocytes
  There are two types of lymphocytes. B cells produce antibodies and T cells target cancerous cells and cells infected with viruses. A normal lymphocyte proportion is about 20-40 percent. CD4 and CD8 cells are types of T cells that are measured separately.
• Monocytes and macrophages
  These cells engulf or “eat” and destroy foreign invaders, or disease-causing organisms (“germs”). They normally make up about 2-10 percent of all white blood cells.
• Eosinophils and basophils
  These cells play a role in allergic reactions, and defend against parasites. They normally make up about 1-8 percent of white blood cells.

• Platelets (thrombocytes) These cells are necessary for blood clotting. A normal platelet count is about 130,000-440,000. If your platelet count is low, you may bleed or bruise easily.

Blood chemistry tests measure important substances in the blood. They can help show how well organs like the liver and kidneys are working, and can provide useful information about drug side effects. A blood chemistry screen usually includes:

• Electrolytes
  These particles play important roles in the healthy functioning of cells, nerves, and organs. Specific electrolytes by name include bicarbonate, calcium, chloride, magnesium, phosphorus, potassium, and sodium. Electrolyte imbalances may be caused by not getting enough nutrients (malnutrition), kidney problems, or not getting enough water into your body (dehydration, which can be caused, for example by lots of vomiting or diarrhea).
• Liver function tests
  These tests help measure how well your liver is working. High levels of two key liver enzymes—alanine transaminase (ALT or SGPT) and aspartate transaminase (AST or SGOT)—may be a sign of liver damage. Normal levels for women are up to about 40 for ALT and 35 for AST. Several HIV drugs can cause elevated liver enzymes, so especially if you’re taking HIV drugs, your doctor will want to monitor AST and SGOT levels in your body. High levels of bilirubin (a blood pigment) may also indicate liver problems. A normal bilirubin level is 0-1.3.
• Kidney function tests
  These tests help measure how well your kidneys are working. They include blood urea nitrogen (BUN), creatinine, and uric acid. Kidney tests are especially important if you are taking Viread (tenofovir).

In recent years there has been a lot of talk about elevated fat (lipid) and sugar levels in people taking HIV drugs. High blood fat levels can lead to heart disease, while high blood sugar may be a sign of diabetes or insulin resistance (when the body does not respond to insulin). Your doctor should measure your blood fats and sugar regularly if you are on HIV treatment. Exercise, changes in diet, and certain medications can help lower high blood fat and sugar levels.

• Total cholesterol
  Cholesterol is a fatty substance that circulates in the blood. A normal total cholesterol level is 120-240. The U.S. government recommends that you should try to keep your total cholesterol below 200.
• Low-density lipoproteins (LDL)
  This is “bad” cholesterol, which can clog the arteries. You should try to keep your LDL level below 100.
• High-density lipoproteins (HDL)
  This is “good” cholesterol, which helps reduce the risk of heart disease. You should try to get your HDL level up to at least 40.
• Triglycerides
  After eating, energy that is not needed right away is converted into a substance called triglycerides, which is stored in fat cells. A normal triglyceride level is about 45-150. Very high triglyceride levels can cause pancreatitis (inflammation of the pancreas, a serious condition).

Since many HIV+ people have no noticeable symptoms of health problems, it is important to get regular lab tests to monitor how you are doing. These tests are valuable tools that can indicate if something is wrong. CD4 cell counts and viral load test results can help you make decisions about starting, stopping, or switching treatments. Abnormal CBC, blood chemistry or blood fat or sugar tests can indicate other health problems that may be related to HIV or to HIV drugs that you might be taking. Regular monitoring is an important way to take charge of your health.

1		Highleyman, L. (2003). Monitoring tests for people with HIV.  Bulletin of Experimental Treatments for AIDS: Retrieved July 2003 from http://www.sfaf.org/treatment/beta/b53/b53_monitoring.html.
2		Hogg, R. et. al. (2001). Rates of disease progression by baseline CD4 cell count and viral load after initiating triple-drug therapy. Journal of the American Medical Association, 286(20). 2568-2577.