Optimal dialysis - beyond Kt/V

Dr. Agar includes in his discussion of solute removal (part 1; part 2) a wish for a more meaningful measure of dialysis effectiveness.

This is why many (me included) are disenchanted with Kt/V_urea and think it is hardly worth the paper it's printed on. The one thing Kt/V_urea has done is to set a minimum dialysis dose for all patients to achieve.

Do we need a Kt/V_phosphate, a Kt/V_{β2 microglobulin}, a Kt/V_whatever? Maybe, but that could get very messy. A better way to measure "good dialysis"—and this might include Kt/Vurea, measures of body fluid levels, and possibly of middle molecule removal too—is badly needed but sadly lacking. Is this so hard? I don't think so; it is simply that we have been so locked into Kt/Vurea that we have been blinded to better ways to assess "good" dialysis. So, watch this space!

I will be very interested in what he and his colleagues can come up with but any measure based on pre and post dialysis blood draws taken once a month will be limited because they are just two snapshots. I can see how better tests would give a more complete picture of the effectiveness of dialysis but it will still be suboptimal. It's frustrating when feeling unwell to hear from a doctor that based on the lab report I should be feeling great. The measure that would be optimal is one that would directly measure "health".

We'd have to agree on what we mean by health. I think when it gets right down to it we mean life span, specifically life span while living the life we mean to live. For obvious reasons mortality isn't an optimal measure for an individual but what if you looked at the cells instead of the whole? How are the "people" in Dr. Agar's city of the body?

I propose that measuring the average lifespan of the body's component cells would give a good indication of the effectiveness of what ever it is you're doing.  Just as people in the modern world have shortened lifespans when they live in an unhealthy environment, cells in the polluted environment of a chronically under dialyzed person would have a shortened lifespan. The health or ill health of the cells should directly correlate to the individual's personal sense of health.

If we could easily measure the average life span of cells, blood cells or even skin cells,if we were able to measure the cell's age at death, then we would have an indication of the environment in the interstitium and the environment in the intracellular fluid compartment. Or if we could measure the age of each cell in a sample then we could infer from the age distribution curve the health of the cells generally. Humans may be greater than the sum of their parts but the health of those parts must matter.

I think all of medicine would benift from an easy, routine way to measure the age of cells.