Kidney care guide
What the weight between two sessions is actually telling you
Over a few days the scale is measuring fluid, not body mass — which is why your unit cares about the difference between two weights rather than either one on its own.
The AEVONA care team7 min read
In short
- Between two sessions, almost everything the scale registers is fluid your kidneys are no longer removing.
- The figure that matters is the gain since your last session, not the weight itself.
- Same scale, same time of day, same clothing — otherwise the trend is measuring your habits, not your fluid.
- Dry weight is a clinical judgement that gets revised. It is not a fixed number you own.
Before you read this
AEVONA is a self-management diary and a booking service. It is not a medical device, it does not diagnose, and it never replaces your nephrologist or dialysis team. Always follow the advice of your treating clinician.
Most people on maintenance haemodialysis are told their weight matters more than other patients', and then left to work out why. Here is the short version. Over three or four days your muscle and fat do not change in any way a bathroom scale can detect. Almost everything the scale registers between two sessions is fluid — water and salt that working kidneys would have passed out, and yours no longer do.
That reframes the number completely. A weight reading on a Monday morning is not a verdict on your body. It is a measurement of how much fluid is currently waiting to be removed.
The number that matters is a difference, not a weight
Your unit is not especially interested in 62.4 kg. It is interested in what 62.4 kg is compared with the weight you walked out at after your last session. That difference is your interdialytic weight gain, and it is what the machine has to take off in the hours you are on it.
How much has to come off, and how fast, is a large part of why one session feels fine and the next leaves you flattened. Cramping, dizziness on standing, a headache afterwards, a long afternoon of exhaustion — these are often the cost of removing a lot of fluid in a short time. The same four hours, with less to remove, is a different four hours.
Why dry weight keeps moving
Dry weight is the weight your team aims to leave you at when the excess fluid has been taken off. It is an estimate arrived at clinically — from your blood pressure during and after sessions, from swelling, from breathlessness, from how you say you feel — and it is revised over months.
It has to be revised, because real body weight does change. Someone whose appetite improves and who puts on genuine muscle and fat will find an old dry weight is now set too low: sessions start pulling them below where they should be, and the cramps and thirst that follow look like a fluid problem when they are actually a stale target. The reverse happens too, after an illness or a long hospital stay.
Ask your unit
Your dry weight, and any gain your team wants you to stay under, are set by your unit and reviewed by your unit. Nothing here is a target. If your sessions have started to feel different — more cramping, more dizziness, more breathlessness lying flat — that is a conversation to have with your unit before your next session, not a number to adjust yourself.
Weighing yourself so the number is worth recording
A home weight is only useful if it is comparable with the last one you took. Most of the noise people see in their own records is method, not fluid.
- Use the same scale every time. A domestic scale and your unit's scale will disagree, and that is fine — you are tracking change, not trying to match the unit.
- Put the scale on a hard floor. A mat or carpet will read differently, and will read differently again depending on where you stand on it.
- Weigh at the same point in the day. First thing in the morning, after passing urine and before eating or drinking, is the easiest to repeat.
- Wear roughly the same amount of clothing, and note it if you could not.
- Write down the number you actually saw. Rounding 62.4 to 62 throws away exactly the change you were trying to see.
What a trend shows that one reading cannot
A single gain tells you almost nothing — everyone has a heavy day. A month of gains side by side tells you something you cannot get any other way, and it is the kind of thing worth bringing to a review appointment rather than trying to interpret alone.
| What you might see across a month | Why it can be worth mentioning |
|---|---|
| Gains creeping upward session after session | Could be fluid, could be salt in the diet, could be a dry weight due for review. Your unit can tell these apart; a scale cannot. |
| One much larger gain, then back to normal | Usually a single identifiable day — a wedding, a fever, a hot day of travel. Worth noting alongside the reading so the outlier is explained. |
| Gains falling while cramps get worse | Tell your unit before the next session rather than after it. |
| The gain after the long gap always the largest | Expected on a Monday–Wednesday–Friday schedule. Three days between sessions is longer than two, so more accumulates. |
What AEVONA deliberately does not do is tell you what your numbers mean. It keeps your record legible so that you and the people treating you are reading the same thing. The reading is yours; the interpretation is your nephrologist's.
Sources for the AEVONA claims above
PRS §5.2 FR-2.1–FR-2.6PRS §4.2PRS §5.10
The clinical explanation in this article is general orientation prepared by the aevona care team. It cites no protocol and sets no targets, because the targets that apply to you are the ones your own dialysis unit has given you.