CD4 units (absolute vs. %)

Question

I was wondering what the units are when reporting CD4 counts. When someone says the patient's cell count is 333 is that absolute no. of cells per mL or is that 333,000 cells per mL. I'm a little confused because I read somewhere that treatment should be started when the cell count is below 200,000 cells/mL so does this mean that the number reported as 333 is actually 333,000. Also, what does the % mean (percentage of what)?

Answer

Thanks for your post.

CD4 absolute counts are typically reported in cells per uL (microliter). Since there are 1000 microliters per milliliter (mL), a count of "333" cells/uL is equivalent to 333,000 cells per milliliter.

CD4% is a different way of reporting the quantity of CD4 cells. The value is unitless, and refers to the percentage of lymphocytes (CD3+ cells) that are CD4 positive. Knowing this percentage and the total amount of lymphocytes allows for the calculation of the total (or absolute) CD4 count.

Hope this helps, thanks for reading. BY