#cd4 percent

[hivforum]

The 4 CDC Stages of HIV Disease use both CD4 and % according to what I'm reading. What I don't understand is if a person's CD4 nadir was 350, but had a % <14, does that make him Stage 3?

No, the CDC staging system carries this important footnote: “The stage is based primarily on the CD4+ T-lymphocyte count; the CD4+ T-lymphocyte count takes precedence over the CD4 T-lymphocyte percentage, and the percentage is considered only if the count is missing.”

[hivforum]

I came across a discussion about CD4 and CD4% disparities. While they didn't say, I assumed they were discussing those not on meds yet. The discussion was about someone with a CD4 of 500-800, for example, but a CD4% in the 20's. Some were saying a CD4% of 25 would be expected to have an absolute in the 300's. So, they were saying the labs can "lie," and be giving a false story to the state of the immune system. This had me thinking about those living where they still have CD4 requirements.

This is an good question that I should have answered earlier—my apologies.

It’s true that there is a typical correlation between CD4 count and CD4 percent. For example, a CD4 count of 200 generally corresponds with a CD4 percent of 14%, and someone is defined as having AIDS if either the absolute count or percent are lower than those thresholds.

However, like all biological phenomena, this is just an average. It’s not unusual to be an outlier in either direction: you can have a high CD4 count with a lower CD4 percent, or vice versa.

Conditions (e.g. some infections) or drugs (e.g. Bactrim) that lower your white blood cell count or lymphocyte count will also lower your absolute CD4 count but will not affect your CD4 percent. On the other hand, your CD4 count may be unusually high—and out of proportion to your CD4 percent—if you’ve had your spleen removed or if you’re also infected with HTLV-I. But by far the most common reason for CD4 count/percentage disparity is just normal variation.

These disparities raise the obvious question: Which number should you believe? Many years ago, I wrote a paper showing that in the Moore Clinic database at Johns Hopkins, the CD4 percent added little useful information (in terms of predicting the risk of opportunistic infections) above and beyond the information you got from the absolute count. However, other studies have suggested that the CD4 percent is sometimes a more reliable indicator of immune function than the CD4 count. Also, the percent is less variable than the count, so it can be helpful when your CD4 count is fluctuating or inconsistent with previous values. Knowing that the CD4 percent is stable is reassuring in those cases.

Fortunately, I would like to think that we’re moving into a “post-CD4 era,” in which people are diagnosed early, start effective treatment while they still have high baseline CD4 counts, and maintain undetectable viral loads. In such cases, no one should care about either the CD4 count or percent. When things go that way, continued CD4 monitoring is now considered “optional” in the U.S. treatment guidelines.

[hivforum]

Is that the absolute % of the lymphs" ?

The CD4 count is roughly the absolute lymphocyte count multiplied by the CD4 percent.  But don’t try to do the math yourself and expect it to come out that exactly right…it just doesn’t work that way.

[hivforum]

In ur book it says to look at your cd4 percent vs your cd4 count is this the same as ratio?

No, not the same.  The CD4 percent is the percent of lymphocytes that are CD4 cells.  When you order a CD4 count, you always get a CD4 percent as well.  The CD4 percent tends to be a little less variable than the CD4 count.

The “ratio” is the ratio of CD4 cells to CD8 cells (CD4/CD8).  It is not a recommended test, but used to be commonly ordered.  It’s more expensive, but provides no additional information that’s useful.