Do Diuretics ever play a role in dialysis patients? I understand that they get rid of extra fluid by making you urinate more so does this mean little benefit for dialysis patients who have little or no urine production? Can this process translate into easier fluid removal during dialysis and help alleviate conditions like ascites in dialysis patients? Thank you.

Dear Unregistered,

The use of diuretics may still have value in many patients even after starting dialysis if they have residual renal function. The US uses less diuretics than in Japan and Europe. Some studies have shown reduced interdialytic weight gains as well as lower levels of potassium thus reducing episodes of hyperkalemia. However, in anuric dialysis patients, it has no means of action to work any longer, but it can be an effective treatment to augment dialysis treatments in those patients that still have enough renal function. There is also a suggestion of benefit with reduced cardiac specific mortality by as much as 14% in some studies in those patients continued on diuretics. As in all aspects of medical therapy, it must be considered in conjunction with all of the medications and conditions that a patient has while under the care of a multidisciplinary team headed by a nephrologist. As with all patients on diuretics, controlling salt intake is paramount in maximizing the effectiveness of any diuretic used. Nevertheless, the majority of American nephrologists appear to discontinue diuretics within 90 days of starting dialysis, but in patients with residual renal function, continuing diuretics may have a significant benefit on a case by case basis.

Ascites is a complex condition based on many factors especially that of protein/calory malnutrition where patients have very low albumin levels. This is quite common in many dialysis patients and leads to high mortality especially from sudden cardiac death. Ascites in dialysis patients is fortunately not common and can be further controlled with more frequent dialysis as well as improving albumin levels to increase plasma oncotic pressures. Since ascites has many different conditions that can cause this third space fluid retention, a complete examination of the ascitic fluid is usually performed to eliminate any secondary causes of ascites beyond that of fluid overload from poorly controlled ESRD. That is the world of medicine to always consider what other processes may be masquerading as a common complication. In general, in well dialyzed patients, there should never been any patient with ascites.

Ascites can be a symptom of the uremic syndrome but fluid around the heart sac called a pericardial effusion is more common and more dangerous in that it can cause a condition called cardiac tamponade which is a medical emergency. Fortunately, with effective chronic and emergency treatments for ESRD, the incidence of developing pericardial effusions or ascites is becoming very uncommon. It should never occur in a well managed dialysis patient monitored for proper dry weights, dietary salt restrictions and adequate protein intake to keep albumin levels higher than 4.0. While diuretics may have a place in patients with residual renal function, proper dialysis prescriptions and dietary compliance is the most important factors in maintaining fluid hemostasis in dialysis patients.

Re Diuretics

Again … Peter Laird is doing my job for me! He has said it all … well, most of it.

But … for what it’s worth, let me add the following … my answer to your question is … YES … I do use diuretics in selected dialysis patients … and let me tell you the reasons why!

One of the greatest boons for a patient who has started dialysis is to still pass some urine.Why? Because more urine ‘out’ means more fluids ‘in’.

OK … lets follow this through …

Pee an extra litre on any given day … and that then means that there is an extra litre that you can drink on that day!

The amount of fluid a dialysis patient can ‘safely’ drink from one dialysis to the next (well, that means for most dialysis patients as there sometimes are some exceptions) is the amount you pee + your daily ‘insensible losses’ + maybe (again, for most) about 500 ml or 'metabolic need.

So, let’s look at all fo that. Firstly, what are ‘insensible losses’.

(1) Look at a crowd on a chilly morning … you will see lots of ‘breath’ puffs … visible clouds of what looks like steam when they are breathing out. I will probably look just like that when I land in Seattle on Thursday! This is water of condensation … moisture lost in every breath from the lungs as we breath out. And, as that moisture is at body temperature (37C) when it hits the cold atmosphere, it condenses like a barely but just visible mist. We see it as those little puffs of mist when we breath out. This is happening every breath, evry minute, every day, even hot days. But, when the outside temperature is warm, it doesnt condense as mist as it hits air or equal and not lower temperature … and so we just dont see it - but it is still happening and the losses are still there!.

(2) We all feel uncomfy in humidity or heat … we sweat. Patches under the arms, a trickly down the back. Sweat is obvious during heatwaves or hot days or when we exert. But, even when we are unaware, we are losing water from the skin every minute of every day. It is wafted away (and sometime a bit ‘woofily’, too, if we havent washed well or arent wearing a dedorant) by air currents, it is absorbed by our clothing or it is evaporated bysurrounding warmth or heat … but, all the same, the losses are ongoing.

(3) We lose fluid in our motions - they are soft and goey and carry quite a bit of water within them as a moistener … and, in addition, we all know the significant losses we can have if we have a tummy bug with copious diarrhoea! Every time we pass a motion, we lose some fluid too. Maybe not much - but maybe more than you think.

(4) If we have open wounds, fevers, burns, drain-tubes after surgery of have an operation where blood loss happens - all these can add to the losses of fluid from the body.

All these, (1) + (2) + (3) +/- (4) = our insensible losses. Insensible losses therefore = ‘those losses which we cannot easily measure’.

But … we CAN measure urine - easily - by peeing into a measuring cup! And, our urine losses, normally, are our major losses.

Thus, we humans lose fluid, daily, as a composite of urine + all manner of insensible loss.

Insensible losses, in effect, at the ‘normal’ temperatures of a temperate climate, have been estimated at ~500ml a day. They can be measured with very careful weighing techniques combined with the measuring of fluid intake and measured urine output but, for all intents and purposes, you can figure on about 500 ml/day in normal circumstances.

So … our daily losses are 500ml (insensible) PLUS whatever volume of urine we pass on that day (a day means 24 hrs)! Just think to when you have been hospitalised - all that measuring and weighing! it is actually one of the most important records we keep of a patient in hospital - and I am a stickler for good ward measurements and weights … but maybe that’s just my obsessive/compulsive side briefly dominating my excentricity and extroversion!

Our daily intake can (generally and safely) be our measured and unmeasured losses PLUS the water we need, daily, to feed our metabolic factories - our cells. That is, give or take, another 500 ml (or thereabouts)!

Pee NIL … then intake is 500 ml insensible + 500 ml daily metabolic need + measured losses (0) = 1 litre daily.
Pee 1 L … then inatke is 500 ml insensible + 500 ml daily metabolic need + measured losses (1L) = 2 litres daily
Pee 1.5 L (you wish!) … then intake is 500 ml insensible + 500 ml daily metabolic need + measured losses (1.5L) = 2.5 litres daily

Its simple maths!

Back to diuretics. Yes … I do use them in dialysis patients - to a point. As Peter observed, for reasons I do not fully comprehend, US practices seem not to. European, Japanese (and Australian and New Zealand) … all ‘the rest’ … do! Another oddity of 'the rest of us" … or another oddity of the US? I’ll leave that one hang!

But, it is a fact that, especially in the 1st year or two (or three or even sometimes four) after the onset of advanced CKD and the need to start dialysis, many patients do retain a urine output (of sorts). That urine doesnt contain much (or enough) wastes (urea, creatinine, phopshate, etc etc) - but it does still have a volume - and that volume is salt (some) and water (sometimes significant water)!

If a diuretic can enhance (or maximize) that water and salt component (and loss) - even if it is by a few hundred mls a day, that frees up the patients’ allowed intake by the same amount. Diuretics wont enhance waste clearance to any significant degree, so don’t think they might ‘get you off dialysis’ … sadly, not a chance … but they can, and do, drive higher volume losses in some (though not in all) patients.

It comes down to a comfort thing! Again, the diuretic wont keep you off (or get you off) dialysis … no way … but it will (or may) help you be more comfortable within your fluid restriction - and lift your fluid restriction partially or even fully.

Some patients get no diuretic response. That is a sad but true fact. If not, there is no benefit in pushing and pushing. No response = no response! Move on to something else. In others, however, a diuretic can mean the difference between draconian and tolerable fluid restriction.

Over time, the ‘response’ of the still failing, still shrinking, still dying kidneys to a diuretic (and this is commonly a ‘loop’ diuretic like frusemide … or in the US, furosemide) tends to lessen. There will come a time. sooner or later, when it becomes clear that the urine output is drying up, despite the diuretic. There is no advantage, then, of flogging more and more diuretic beyond that point - rather, the patient and I have to accept graceful defeat and withdrawal of the diuretic is then the sensible decision.

Clearly, as the diuretic response fades and fails, so, too, will fluid intake restrictions need to be correspondingly tightened! I hate doing this to a aptient, but if what is happening is explained clearly, I usually find no problems with compliance and with acceptance. But, till that point …?

I’ll let you think on that one …

So, for all the reasons Peter gave - and they were all correct and I agree entirely … yes … I do use diuretcs where I think there is a response. Not in all, but where it seems the diuretic is making an intake difference for the patient.

One more thing … some diuretics (like frusemide) also can act as veno-dilators … they expand venous capacitance and reduce what is called the ‘pre-load’ on the heart. Not by much - but by a little. And, for that reason, too, thay can play a useful role - but I wont muddy the water with that issue now. It is more complex, but it is another little ‘string’ to the diuretic ‘bow’ which can be useful in patients with wonky hearts.

The ‘fluid in, fluid out’ value of diuretics in a dialysis patient is their key advantage - and I, for one, still use diuretics in (selected) dialysis patients. I know what I have said may spark controversy with some - but, hey … you believe what you believe, right?

This is one area where US opinion can be at odds with those of others. I will let you make up your own mind.

John Agar