Kt/V is flawed Yes or No

[jester]

Hi

I've been reading more and more about Kt/V being flawed and if that's the case what about URR ? Richard  C/O  Jessie

[kitkatz]

From what I have read and heard the KT/V is a guess as to how well the blood may be being cleaned by dialysis.  It is a poor way of doing it, but it seems to be the only one the medical profession has come up with to use so far wth dialysis patients.

[BigSky]

Flawed?? What do you mean flawed.

I think the entire picture of Kt/V, URR, labs and how the patient feels brings a much better picture of adequate dialysis than just to rely on any one single thing.

[AlasdairUK]

I assume you are talking about Kt/V Urea. I think Kt/V is a good indicator as to how adequate your dialysis is and what changes need to be made in increasing your dialyzor size or increasing length to insure that you receive adequate dialysis.

I think Kt/V is a better measure than URR as your URR can be adequate while your Kt/V might be inadequate. This is because URR only measures the reduction of urea in the blood and urea being so small it dialysis out easily, but when you get to a certain point you will not remove any more urea from the blood while the tissue in your body might still have a high concentrate of urea and it will take time for the urea in the tissue to move into the blood before it has the chance to be dialyzed out. Kt/V measures the urea in the entire body not just in the blood.

When you say Kt/V is flawed I assume you mean that they do not meassure the removal of bigger particles so your Kt/V urea might be adequate while still receiving inadequate dialysis as you are not removing enough of the larger particles such as macroglobulin. It is safe to assume that if you are not removing the smaller particles well (urea) you are not removing the big particles either, if your Kt/V urea is inadequate the rest of your Kt/V's would also be inadequate . So if your Kt/V urea and the rest of your labs are good then you can assume your overall Kt/V is adequate.

How else would you measure adequate dialysis?

http://en.wikipedia.org/wiki/Kt/V

[kitkatz]

Beats the hell out of me how to measure it better, but I think there has to be a better way. The medical profession has not found it yet.

[Joe Paul]

Flawed?? What do you mean flawed.

I think the entire picture of Kt/V, URR, labs and how the patient feels brings a much better picture of adequate dialysis than just to rely on any one single thing.

I agree with BigSky 

[Bill Peckham]

I think a much better measure would be if we could find a way to routinely determin the average age of blood cells and by that determin the average lifespan of blood cells. I think that average blood cell lifespan would be a comprehensive measure of dialysis quality/dose. My understanding is that in a healthy body blood cells live around 120 days, while in a person dialyzing incenter that can be down to 60 days. I would bet that blood cell life span has a linear relationship with the HemoDialysis Product http://en.wikipedia.org/wiki/Hemodialysis_product i.e. as dose (length x frequency squared) increases average blood cell lifespan would increase.

I talked to some doctors about what it takes to measure the age of a blood cell - thinking that if you could say what the average age is then you could guess the average lifespan. The way they knew involved using some radioactive isotope which did not sound routine but maybe there is a way to it, there is some amazing diagnostic equipment out there, computer driven gene sequencing machines and such, maybe kt/v will some day be replaced by average blood cell lifespan.

One thing about kt/v besides it measures an easy to remove nontoxic molecule, it also ends up being a goal rather than a floor. kt/v targets are adequacy goals, you have to do at least that well. Our goal should be optimal dialysis or if we make compromises we should do so as a fully informed personal choice. It is easy to not mind if your kt/v goes from 1.40 to 1.26 but if your average blood cell lifespan went from 90 days to 81 days you might choose to dialyze a bit more.

[Zach]

Here's an old thread about Kt/V:

http://ihatedialysis.com/forum/index.php?topic=1271.0