Do You Continue to Make Urine After Starting Dialysis?

Residual Renal Function (making urine after starting dialysis) is a good thing!

Residual Renal Function rules!. Getty Images/Thomas Barwick

DO KIDNEY DISEASE PATIENTS MAKE URINE AFTER STARTING DIALYSIS

To paraphrase Obama, yes you can. Unless your kidneys have completely shut down and the GFR has gone down to absolute zero, many patients will continue to produce urine even after starting dialysis. However, just because you make urine does not necessarily mean that you don't need dialysis.  The decision to initiate and maintain dialysis is based on multiple factors including lab tests and patient's symptoms and not necessarily on the volume of urine one makes.

In simple terms, kidney function that remains after one starts dialysis is called residual renal function.  It could be a very small fraction of what normal kidney function is

Factors that determine whether one might preserve residual renal function could include :

  • In general, patients on peritoneal dialysis will tend to make urine from their kidneys longer than patients on hemodialysis. 
  • Cause of kidney failure makes a difference
  • Blood pressure control: Drops in blood pressure will tend to accelerate the loss of one's residual renal function
  • Medications: certain ones could help your cause, while others could hurt (see below)
  • Nonwhite race is associated with a faster loss of residual kidney function
  • Female sex

For details statistics regarding the above factors, take a look at this table.

DOES IT MATTER WHETHER A PATIENT MAKES URINE EVEN AFTER STARTING DIALYSIS? WHY IS IT IMPORTANT TO PRESERVE RESIDUAL RENAL FUNCTION 

As insignificant as it might seem, residual renal function is a big deal and maintaining it is of utmost importance.

These are some reasons why maintaining even a little kidney function after someone gets started on dialysis could make a big difference:

  1. Patients who have significant residual renal function tend to live longer.  Multiple studies have corroborated this. Take a look at some examples here, and here.
  2. Patients with intact residual renal function are more likely to receive adequate dosage of dialysis (yes, like any other medication, there is a certain minimum amount/dose of dialysis that one needs to receive to get its benefits).
  1. Quality of life is better.  This is partly related to patient's ability to get away with less strict dietary restrictions.  They can also be a little more liberal with their fluid intake.

WHAT CAN YOU DO TO PRESERVE RESIDUAL RENAL FUNCTION FOR LONGER

This is an active area of research in nephrology.  What we do know so far is that certain interventions can help preserve residual renal function better and longer, and therefore might translate into a longer lifespan and a better quality of life for dialysis patients.  Some of these interventions are:

  • Good blood pressure control
  • Tight blood sugar control
  • Use of certain medications, called ACE inhibitors has been shown to help
  • Conversely, avoiding certain medications that are known to be toxic to the kidneys makes sense; like NSAIDs (or nonsteroidal anti-inflammatory drugs), aminoglycosides, Amphotericin B, etc.
  • Considering starting kidney failure patients preferentially on peritoneal dialysis (the so-called peritoneal dialysis-first strategy. However, this remains a subject of debate).

​CONCLUSION 

Consider yourself lucky if you still continue to make some urine after starting dialysis.  Even though it might seem insignificant, having even a little bit of urine output could make a big difference to your life expectancy as well as a quality-of-life.  So if you are on dialysis but still make some urine, please do not have an "I have nothing to lose" attitude when it comes to maintaining your residual kidney function.  

And the next time, anybody says, "It doesn't matter.  Ms/Mr. X is already on dialysis.  Hence, they can get NSAIDs or intravenous radiocontrast"...ask them to talk first to your friendly nephrologist.

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