CD4 count: Measures the health of your immune system and your risk for opportunistic infections (OIs). Higher numbers are better. The most important test for deciding whether to start antiretroviral therapy (ART) and OI prophylaxis (preventive therapy). Ordered at baseline and repeated every 3-6 months.
Viral load: Measures viral replication (the activity of the virus). Lower numbers are better. People with high viral loads tend to progress more rapidly than people with low viral loads. The most important measure of whether your drugs are working: it should become undetectable on treatment. Ordered at baseline and repeated every 3-4 months.
Resistance test: Determines whether your virus is resistant to antiretrovirals (ARVs). Should be ordered at baseline and whenever your treatment is failing with a viral load of over 500-1,000. There are two types of resistance tests. Genotypes look for mutations that cause drug resistance. They're cheaper, faster, and fine for most purposes. Phenotypes measure how well the virus grows in the presence of varying concentrations of ARVs. They have advantages in people with a lot of resistance, especially to protease inhibitors (PIs). The combined test (PhenoSense GT) measures both. The virtual phenotype (VircoTYPE) uses a genotype to estimate the phenotype.
Complete Blood Count (CBC): Measures your white blood cell count, red blood cell count, platelet count, hemoglobin, and hematocrit. A low hemoglobin and hematocrit mean you're anemic. Ordered at baseline and every 3-6 months (usually whenever you get a CD4 count). Should be checked more frequently after starting AZT, which can cause anemia.
Comprehensive Chemistry Panel: A collection of tests, including measures of liver damage and kidney function. Ordered at baseline and on a regular basis, with the frequency depending on whether you're taking drugs that can affect the liver or kidneys.
Toxoplasma IgG: Determines whether you've ever been infected by the Toxoplasma parasite, which can cause brain lesions in people with CD4 counts below 100. Ordered at baseline, and sometimes repeated if your CD4 count is below 100, to determine whether you need to take prophylaxis.
CMV IgG: Determines whether you've ever been infected by CMV (cytomegalovirus). Usually ordered once at baseline. Not a critical test since most people's tests are positive, and there's not much you can do with the results anyway.
Lipid panel: Measures your triglycerides and your total, HDL, and LDL cholesterol, which help determine your risk of heart disease. Should be ordered after an overnight, 12-hour fast at baseline and approximately once a year, especially if you're on drugs that can increase lipid levels.
Fasting glucose (blood sugar): A test for diabetes or insulin resistance. It's included in the comprehensive chemistry panel, but the result is most helpful if you're fasting. Ordered at baseline and approximately once a year, especially if you're on drugs that can increase blood sugar or cause insulin resistance.
Pap smear: A screening test for cervical dysplasia (abnormal cells) or cancer in women that looks for abnormal cells caused by HPV (human papillomavirus). Done at baseline and at least every year after that -- more frequently in women with abnormalities. An abnormal Pap smear should lead to colposcopy, a test that allows abnormal areas to be biopsied. Anal Pap smears are now being performed at many centers to look for anal dysplasia and cancer in both men and women, especially those who have had anal sex. An abnormal anal Pap smear should be followed by high resolution anoscopy (HRA).
TB skin test (PPD): A skin test that tells you whether you've ever been exposed to the bacterium that causes tuberculosis (TB). If the test is positive, you should take nine months of INH (isoniazid) to prevent active TB, after being checked to make sure you don't already have it. The test should be done at baseline, then every year in people at high risk for TB. The test is less accurate if you have a low CD4 count, so it should be repeated after your CD4 count goes up on ART.
Urinalysis: The best reason to get a baseline urine test is to find out if you have protein in your urine. This is especially important if you have diabetes, hypertension, or if you're black, since blacks are at risk for HIV-associated nephropathy (HIVAN).
Syphilis: A blood test (RPR, VDRL, STS, and others) is used to diagnose syphilis and to make sure that treatment of syphilis has been effective. Ordered at baseline and at least every year (or whenever there are symptoms).
Gonorrhea and Chlamydia: In men, urine tests can be used to diagnose these infections if they're in the penis. In women, cultures are sent during routine pelvic exams. Men or women who have anal sex should also be tested with rectal swab cultures. Throat cultures are used to look for oral gonorrhea (but not Chlamydia). Recommended at baseline and every year (or whenever there are symptoms).
Hepatitis A: The total hepatitis A antibody (anti-HAV total) tells you whether you've ever been exposed to hepatitis A. If it's negative, consider getting a hepatitis A vaccine, especially if you also have hepatitis C. If it's positive, you're already immune.
Hepatitis B: The surface antibody (HBsAb) tells you whether you're immune to hepatitis B. The surface antigen (HBsAg) tells you whether you have hepatitis B (either acute or chronic). If both are negative, you should get vaccinated against hepatitis B. If the HBsAb is positive, you're immune. If the HBsAg is positive, you'll need further testing, including a hepatitis viral load (HBV DNA), an "e antigen" (HBeAg), and a scan of your liver.
Hepatitis C: The antibody (anti-HCV) tells you whether you've been exposed to the hepatitis C virus (HCV). If it's positive, the HCV viral load (HCV RNA) then tells you whether you have chronic infection. If that's positive, you'll need further testing, including an HCV genotype and a scan of your liver. People at risk for hepatitis C (especially injection drug users or people with unexplained liver abnormalities) should get an HCV RNA even if their antibody is negative.
HLA B*5701: Determines whether you're likely to develop the abacavir hypersensitivity reaction (HSR) if you take Ziagen, Trizivir, Epzicom, or Kivexa. Be sure your test is negative before taking abacavir in any of those forms.
HIV tropism (Trofile ES): Determines whether your virus is "R5-tropic," the kind that responds to Selzentry (maraviroc). If the test shows "dual/mixed-" or "X4-tropic" virus, the drug won't work. Very expensive; should be ordered only if you're considering Selzentry.
Bone density scan (DEXA): Indicated in some people with risk factors for osteopenia (decreased bone density), which include smoking, use of corticosteroids, low testosterone levels, and older age.
Testosterone level: Should be ordered in people with weight loss, fatigue, loss of sex drive or erectile dysfunction, and possibly even depression, since hypogonadism (low testosterone levels) can cause these symptoms. Most accurate if the blood is drawn in the morning.
Chest x-ray: Some doctors order this at baseline to look for TB, cancer, or other abnormalities, but this is not a standard recommendation in non-smokers without symptoms.
Blood culture for AFB: Used to diagnose Mycobacterium avium complex (MAC). Ordered in people with CD4 counts below 50 who have fever, weight loss, or other symptoms. Some doctors order it in anyone with a CD4 count below 50 before starting MAC prophylaxis.
Cryptococcal antigen: Used to diagnose cryptococcal disease, including meningitis. Ordered in people with CD4 counts below 100 who have fever or headache. If it's positive, you need a lumbar puncture (spinal tap).
G6PD: People of African or Mediterranean descent can have a genetic deficiency in glucose-6-phosphate dehydrogenase (G6PD), which can result in severe anemia when certain drugs are taken, including some drugs used to treat or prevent OIs, such as dapsone, primaquine, and sulfa drugs. If you have that genetic background, it's reasonable to get a G6PD level at baseline so you can avoid those drugs if it's low.
Although there are a number of recommended vaccinations, don't rush out to get them as soon as you're diagnosed. They're much more likely to work if your immune system is healthy and your viral load is undetectable. If you'll soon be starting ART, postpone the vaccinations until your viral load is undetectable and your CD4 count has gone up.
Pneumococcal vaccine (Pneumovax): Helps prevent pneumococcal pneumonia, caused by a common bacteria. Recommended at baseline, with a booster after 5 years.
Influenza (flu) vaccine: Recommended every year, usually in October, or November, before flu season.
Hepatitis A vaccine series: Recommended for people who aren't already immune, especially if they have hepatitis C.
Hepatitis B vaccine series: Recommended for people who aren't already immune.
Tetanus toxoid (dT): Recommended for everyone every 10 years.
Vaccines for international travel: People with HIV should generally avoid live vaccines, such as measles-mumps-rubella (MMR), yellow fever, or the live typhoid vaccine. However, the benefit of the vaccine may outweigh the risk in some cases, especially if you have a high CD4 count -- when in doubt, consult your HIV doc or a travel medicine specialist.
There's more to health (and wellness, for that matter) than lab tests and vaccinations, but having a list like this is a good start. For more detailed information on these and other related topics, see my book 100 Questions and Answers about HIV and AIDS and the archived questions in the Q&A Forum of the Johns Hopkins HIV Guide at http://hopkins-hivguide.org.
Joel Gallant, M.D., M.P.H., is Professor of Medicine and Epidemiology at the Johns Hopkins University School of Medicine's Division of Infectious Diseases, and Associate Director of the Johns Hopkins AIDS Service.