That elusive 'Dry Weight'

During our New Year celebrations at office on December 31, 2019, everyone was asked about what their New Year Resolution was. 3 out of 5 people said, 'to lose weight'. I wanted to tell them, "Hook up to a dialysis machine. It can remove 2 kg in 4 hours!"

Dialysis Patients almost always have excess water in their body because their kidneys are not working and removing excess water from the body as urine. This excess water is removed from the body during the Dialysis Session.

While healthy human beings have 24 hours in the day to expel excess water consumed in 24 hours, Dialysis Patients have to get rid of the water consumed in 48 hours in about 4 hours! And this is for those who get thrice-weekly dialysis. For those who get twice weekly, it is even more gruesome.

How do the technicians in your Dialysis Centre know how much water you have drunk between sessions? Even if you honestly told them (which of us really does that?), you could never calculate the indirectly consumed water. Like the water in rice, pasta or dal. 

Technicians rely on the Dry Weight. Dry Weight is your body weight in the absence of any excess water. That would be the weight if your kidneys were working.

How do you know what the Dry Weight is? Unless you use a machine like a Body Composition Monitor, which is an expensive machine and not easily available in Dialysis Centres, the Dry Weight can only be indirectly estimated.

If a Dialysis Patient is at their Dry Weight, then they will not have any symptoms related to fluid overload or dehydration. If they are below their Dry Weight, then they could have symptoms such as cramps, low Blood pressure, dizziness, weakness, etc. If they go too much above their Dry Weight, then they could have shortness of breath and cardiac discomfort, high blood pressure, swelling in the limbs, etc.

Technicians typically assess these symptoms and decide on the Dry Weight. Dry Weight can accurately be estimated over a few sessions and it is a very subjective assessment.

You yourself can use the guidelines above to estimate your Dry Weight. The target should be to return to your Dry Weight at the end of every Dialysis Session. (Remember: removing more than 10 ml/kg Dry Weight/hour of water during a Dialysis Session is not safe and removing more than 13 ml/kg Dry Weight/hour is a sure recipe for disaster).

Use the following thumb rules to adjust the Dry Weight:

- If you are experiencing symptoms such as cramps and dizziness, increase Dry Weight by 0.5 kg at a time

- If you are experiencing breathlessness and swelling, decrease Dry Weight by 0.5 kg at a time

Dry Weight adjustment is an art rather than an exact science. Have a discussion with your nephrologist or Dialysis Technicians to determine this together with them. Dialysis Treatments work best when they are looked as a collaborative exercise with your Centre Team.