P.d and fluid overloadingmy son whos 11 is on p.d he has a 600ml fluid

my 11 year old son is on p.d with a 600ml fluid restriction , i have locks on the doors to the kitchen and bathroom and keep a very close eye on him so i know hes not pinching fluid and yet he keeps gaining weight, his consultant says the only way for his fluid overloading is that hes taking extra drink as his u.f is good . they wont listern to me that i know hes not going over his limit, can you tell me if youve heard of this before, and is there any other reason for this … thanks

While we do have a PD expert, Judith Bernardini, at this site … and it might be useful for you to put the same question to Judith as she may also wish to comment (or correct my answer) … I will have a shot at it as we also have a significant PD program at my service where 15% of out total dialysis population are at home on PD (mainly APD).

Firstly, there is much I cannot be sure of from your question:

  1. You do not not say if he is on CAPD or APD (for example, most of our patients on PD are now on APD).

This can matter – especially if he is on APD and is dry during the day when, incidentally, he is likely to be at school and out of your sight. If on APD, he may be UF’ing well at night but, by morning, be relatively ‘dry’ when he comes off. This can initiate thirst - a potent primal reflex in any animal (we are but animals after all) - so that when he gets to school, he is forced by an urge that is irresistible to ‘slake his thirst’ at the tap … in much in the same way an over-fast ‘drying’ on HD turns on the thirst mechanism in HD patients … see previous discussions of thirst at the HD site) and he is ‘urged’ by his thirst mechanisms to drink.

  1. While you note his ‘problem’ weight gain and you say that your nephrologist has said told you that “the only way for him to become fluid overloaded is if he is drinking extra fluid” … it is not clear to me from your post if the weight gain is truly fluid – or whether he might be gaining weight as body weight rather than fluid, or gaining fluid in an ‘inaccessible compartment’.

While I generally deal with adults and not paediatric patients … and an 11 year old boy is still in the child-on-dialysis category … a 600 ml restriction is quite a severe restriction. Whilst I am not saying that your son is – though some kids (and adults) can be a little devious regarding fluid intake and while you may be able to (as in (1) above) be diligent at home and be guarding the home fires against water-consumption, his ‘escape’ to school may be his chance to correct (out of your sight) what he sees as unquenchable thirst.

But, as I’d like to give your lad all due credit for doing his best and accepting that he is fully complying with his fluid restriction, there are other important ‘unknowns’ in your post that may be significant factors out of his control and yet which may be causing unremitting weight gain.

  1. What is his serum albumin? Albumin is a normal blood protein that serves to ‘hold’ salts and water within the circulation, sustaining a normal blood volume. Should his serum (blood) albumin be low - and it is commonly lower in PD compared to HD - then two things happen over which he has no control and for which fluid restriction doesn’t work …

If the blood albuimn is low, salt and water will ‘leak’ out of his capillaries into tissue fluid, leading to a lower blood volume and a higher tissue fluid volume. Albumin is needed within the circulation to ‘hold’ salt and water within the blood compartment and thereby sustain the blood volume. If the blood albumin falls, this is no longer possible. This leads to a loss of ‘volume’ (salt and water) within the blood compartment (circulation) and a gain of ‘volume’ (salt and water) in the tissue compartment.

Here, you may want to read the post discussion back at ‘Dehydration: April 7th 2010’ where I discuss thirst and volume … though it comes in to many of the discussions we have had along the way in the challenging Q&A exercise I try to provide answers for … it may help you understand more.[/SIZE]
This ‘compartmental mismatch’ is a common dialysis situation … where two of the main body fluid compartments – the intravascular (blood) volume and the extracellular (tissue) volume – are out of balance … one having contracted (being too small) and the other expanded (being too big).

If this is the case, your son - and you, too – have no direct control over this.

Albumin is lost in PD patients into the PD fluid and this can be a significant loss. It would be important to know if his serum albumin is low. If so, this may be (1) for nutritional reasons and, if so, this can be corrected (ask how from our dietitian expert, Lee Ann Smith or (2) if his albumin losses are large (eg: from excess PD fluid albumin loss … and this can be measured) and, if this is the case, this can also be corrected for through nutritional supplementation(s).

Most commonly-used PD fluids are glucose-based fluids. These can subject the patient (and especially a growing lad) to a significant glucose load … the sugar being absorbed into the body across the peritoneal membrane, just as wastes and fluid are crossing the other way. This glucose load can be significant … and can be a potent source of body weight gain such that the weight your son is gaining maybe as much a gain in body weight as a failure to lose fluid through fluid retention. As you say, his UF rate is ‘good’ … though I don’t have the numbers and ‘good’ may not be quite ‘good enough’. To judge this, one has to be the lad’s physician.

In all this, I am presuming he has already had serial PET tests and that his PD regimen has been mathematically and computer-modeled against the many and varied different concentration and volume combinations of PD fluids available – including assessments regarding the use of the biocompatible solution choices (eg: physioneal, icodextrin and nutroneal) to ensure that the best fluid combinations are being used.

So, you see, it can be a bit more complex than just ‘fluid in, fluid out’ and putting weight gain down to sneaking fluid when you aren’t looking!

These (and other … yes, there are ‘other’) issues can only be sorted by seeing the boy, examining him, assessing his PD dynamics with a PET test, knowing and understanding the factors that impact on compartmental balance … and none of these can be adequately ‘informed’ through an internet Q&A site. You need to explore some of these ‘other potential contributors’ with your physician but … at the end of tha day, understand that the lad still maybe sneaking fluid, out of your sight, and just be too embarrassed by his inability to control an urge to drink that, frankly, can be beyond the ability of anyone to control … for thirst is (as the HD discussions on this attest) a primal, brutal and irresistible urge.

But, in your son’s defense, more may be happening here than meets the eye and these can be things that are beyond his (or your) immediate control. There is other ‘stuff’ to know about. Discuss this again with his physician. Continue to stand up for your lad - at least until some of these other potential issues can be (1) set aside or (2) grappled with and treated.