Clear up Viral Load (pun intended)

Even though I'm on tx-2 there is much I dont know concernig all this HepCrud stuff. This forum has answered many of my Qs. This forum has also posed more Qs.

I thought I understood VL but,I find that there is another way to read VL. How many ways are there to interpret and display VL.
Please explain.

triggertime
keep the faith @don4get2giggle

T'aint mine but I like it.
   "Common sense is in spite of,
   not as the result of education"

[mremeet]

I'll tell you what I know about it. First there are many possible ways of representing viral load, but only two forms are commonly used today. One is to display viral load in copies/ml. What this means is that the actual number of individual viral particles are "counted up" in a certain volume of your blood (in this case a milliliter (ml), which is about 20 drops). When I was first diagnosed with HCV about ten years ago, my VL was measured using this format. Problem at that time was that there were other ways to measure VL and there was no consistency worldwide on how this was done. This resulted in confusion when attempting to interpret scientific research papers when the scientist A would use copies/ml and scientist B would use some other method of quanitification (a similar thing happens with the various liver fibrosis scales too). It would also cause confusion amongst pateints who may have gotten their blood tested at different labs at different times (making the results difficult to directly compare to one another). This problem was especially prevalant between common European and American test methods.

But since that time, a new "international" standard has been established in an attempt to standardize the way the virus is counted up in our blood. The most common method now is international units per ml, or IU/ml. If you want to display your viral load in IU/ml you take your raw VL in copies/ml and divide it by a number provided by the test manufacturer (usually 2.7 from what I've seen) to give you the same thing in IU/ml. Conversely, you multiply IU/ml by that same factor to convert to copies/ml. Each test manufacturer has a different coefficient depending on the technical specifics of their test. But the bottomline is to standardize your results so that when you see it in IU/ml, it means that the VL measured with that test should be the same as that measured on another manufacturer's test (despite their technical differences) as long as they're both converted to the standard IU/ml format.

Viral loads are usually reported not only in whole number format using IU/ml or copies/ml units, but are also represented logarithmically. By converting a whole number into log format, you're finding out what power that the number 10 would have to be raised to (exponentially) in order to get that same number. For example lets take the number 100 and convert it to a log value: we need to find out what value 10 has to be rasied by in order to get 100. Right off you might see that if you take 10 and multiply it by itself, it will be equal to 100. This is the same thing as "10 squared" or 10X10 or 10 to the second power. So the log of 100 would be 2. Lets do 10,000: what value does 10 have to be raised to to get 10,000? Lets see, 10x10x10 (or 10 to the third power) is 1000. And multiply 1000 by 10 one more time and you have 10,000. So if you multiply ten by itself 4 times (10x10x10x10), you're raising 10 by the fourth power, and you get 10,000. So the log of 10,000 is 4. Lets do it one more time, but this time for a more complicated number that's similar to an average viral load: find the log of 2,300,000. Break out your calculator (you can find it in windows under start-->programs-->accessories and under view select "scientific") and poke in 2,300,000. Then press the log button and you get 6.36 (rounded off). Once again what that means is that if you were to raise 10 by the 6.36 power you would get approximately 2,300,000. Try it on your calculator to see if it works out. And if 2,300,000 is your reported VL, then it will display it as 6.36 in log format.

Now, you might be asking yourself, what's the point of doing all this log cr@p anyway? Without getting too tedious about it, converting to log format can offer an advantage in convenience for the doctor or patient when interpreting your results during treatment. For instance, lets say you started out with a viral load of 2,300,000 IU/ml, or 6.36 log as described above. Now lets say you completed 4 weeks of IFN+riba therapy and had your blood tested. It came back as a VL of 15,500 IU/ml, or 4.19 log. You or your doctor can quickly see that you have lowered your viral load by more than 2 logs because if you subtract 4.19 from 6.36 you get 2.17. This is a greater than 2 log drop in only 4 weeks, which is considered a good response. It quickly tells your doctor that you are responding well to the drugs and things are chugging along nicely. How does your doctor know that? Because all the HCV scientific research papers are standardized and formatted this way. They report likelihood of treatment success by how many logs your VL drops over a given period of time. It's a way of standardizing viral response and taking some of the guesswork out of how a particular patient is responding to treatment when it comes to the varying viral loads of one person to another. It's a way of concentrating on the relative differences between pretreatment VL (whatever that might be) and treatment VL's taken at various intervals. Looking at the raw VL numbers themselves doesn't really give you a quick sense of just how well the treatment is working. But knowing what the log value reduction is over a predetermined (and standardized) period of time provides meaningful response data to your healthcare team.

Hopefully I haven't made it any more confusing, but that's the long and short of it.

[triggertime]

Hopefully I haven't made it any more confusing, but that's the long and short of it.

WOW   Thanx

That is def the long&short of it. Im gona try to save & print this coz I cant even remember the short let alone long of it. Thanx-a-mil

triggertime
keep the faith @don4get2giggle