What is it used for?
A CD4 count may be used to:
See how HIV is affecting your immune system. This can help your health care provider find out if you are at higher risk for complications from the disease.
Decide whether to start or change your HIV medicine
Diagnose AIDS (acquired immunodeficiency syndrome)
	
The names HIV and AIDS are both used to describe the same disease. But most people with HIV don't have AIDS. AIDS is diagnosed when your CD4 count is extremely low.
AIDS is the most severe form of HIV infection. It badly damages the immune system and can lead to opportunistic infections. These are serious, often life-threatening, conditions that take advantage of very weak immune systems.
You may also need a CD4 count if you've had an organ transplant. Organ transplant patients take special medicines to make sure the immune system won't attack the new organ. For these patients, a low CD4 count is good, and means the medicine is working.
