May 25, 2001
When I get my bloodwork back they are always quoting me a percentage. My Doctor tried to explain what it was "metaphoricly", but I still am clueless. He said that mine has stayed at about 34 for about 2 years. My CD4 counts have been anywhere from 450 to 750 in that time frame and viral load is undetectable. I have also been HIV+ for 17 years now, on meds for 4 (ziagen, 3tc, zerit if it matters for this question). If you could explain what this is (and you can be technical...its ok)I'd be grateful. He says 34 is good.
Response from Dr. Young
I'll assume that you are speaking about a CD4 percentage.
CD4 levels are actually calculated from blood by estimating the percentage of lymphocytes (a group of your white blood cells) that are CD4. This percentage is then multiplied by the total white blood cell amount to arrive at the absolute CD4 count.
CD4 percentages remain relatively stable over time and are less subject to day-to-day variations in the total white blood cell count. A CD4% of 34 is essentially normal; you can see that you have a relatively large variation in your total CD4 counts, but apparently have a lesser variation in the percentage.
A metaphor that I use to describe the differences is that the CD4 absolute count is like measuring the total number of purple cars on the highway at any one time- if measured at rush hour, there would be more than at midnight; however, the real question is how many purple cars are there in the city (or CD4s in your body); hence, the percentage of purple cars remains the same at rush hour and at midnight. Percentage is a way to smooth over variations in the traffic.
Hope this helps, BY
Is genotype a good idea?
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