I'm on nocturnal home hemodialysis. So I start my dialysis usually immediately or shortly after dinner. This means that my weight just before dialysis will always show a little more than what it actually is. This makes it very difficult to know what exactly has been my fluid weight gain between two treatments.
The extra weight that shows up because of the food you just ate is never constant. It depends on what you ate and how much and there is no way to tell the exact amount.
So, you never know how much fluid you need to pull of during a dialysis session.
For example, a few days back, my closing weight after a session was 78 kgs. At night, just before my next dialysis session, my weight was 81 kgs. But I had just had dinner. I usually remove 1 kg to account for dinner. So, I assumed my actual weight was 80 kgs. So, I set the ultrafiltration amount to 2.5 liters (to account for the 500 ml of water that I usually consume during dialysis). So, in effect the nett fluid removal would be 2 kgs.
But, in reality it is never so straightforward. The 1 kg that I assumed is the tricky part. It is very difficult to guage the exact amount.
Yesterday for instance, I assumed the 1 kg and ended up pulling off a lot more fluid. The first half of the day I felt like someone had squeezed me and put me up on a line with hangers to dry. I felt giddy, weak and totally drained. I had to drink a glass of fresh lime water and another glass of Thums Up to even begin to feel better.
Now that's the good part of getting too dry! You get to drink a lot of fluid!
I really wish there was a mechanism to measure the exact amount of extra fluid in the body that was not dependent on the weight. Maybe like measruingt he density of the blood? That should be fairly simple to integrate into the dialysis machine itself. But then, that wouldn't account for the extra fluid in the tissues which could be a significant portion.