Most people starting hemodialysis still produce some urine, typically around 500 to 700 milliliters per day, though the range varies enormously from person to person. That number tends to drop over the first year or two on dialysis, and many long-term patients eventually produce little or none. But “normal” in this context is less about hitting a target number and more about understanding that any remaining urine output carries real clinical value, and that the rate at which it declines is something you and your care team can influence.
Typical Numbers at the Start of Hemodialysis
When people first begin hemodialysis, most still have what nephrologists call residual kidney function. The kidneys are failing, but they haven’t shut down completely. A scoping review that pooled data from multiple studies found that the average urine volume at the start of hemodialysis was about 680 milliliters per day. By six months, that average dropped to roughly 560 milliliters, and by twelve months it was around 500 milliliters per day.1Frontiers in Nephrology. Residual Renal Function – How Fast Does the Residual Urine Output Function Decline in the First Year of Haemodialysis? – A Scoping Review Those are averages with wide variation. Some patients start dialysis producing well over a liter a day; others are already making very little.
Peritoneal dialysis patients tend to retain urine output somewhat longer than hemodialysis patients, though this advantage narrows over time. One study of peritoneal dialysis patients found a median 24-hour urine output of 560 milliliters, with the middle half of patients falling between 330 and 950 milliliters.2PubMed Central. Urine volume as an estimator of residual renal clearance and urinary removal of solutes in patients undergoing peritoneal dialysis So even on a different modality, the ballpark is similar: most dialysis patients who still make urine produce somewhere between a cupful and a liter in a day.
The trajectory matters as much as the starting point. Some patients hold steady for years. Others lose all urine output within months. The pace of decline depends on a combination of the underlying kidney disease, the dialysis prescription, blood pressure management, and medication choices.
Why Any Remaining Urine Output Is Clinically Important
It might seem like urine output is beside the point once you’re on dialysis. The machine is doing the work, so who cares if the kidneys contribute a little on the side? Researchers have found, repeatedly, that people should care quite a lot. In the CHOICE study, hemodialysis patients who still had urine output at the one-year mark had roughly a 30% lower risk of death compared with those who had lost all output.3PubMed Central. Association of residual urine output with mortality, quality of life, and inflammation in incident hemodialysis patients: the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease (CHOICE) Study A separate large study confirmed a graded relationship: the faster residual function declined during the first year of dialysis, the higher the mortality risk, and that pattern held across different ages, sexes, races, and whether or not the patient had diabetes.4PubMed Central. Residual Kidney Function Decline and Mortality in Incident Hemodialysis Patients
Preservation of residual kidney function has also been linked to better quality of life, not just longer life.5PubMed Central. Preserving residual renal function in dialysis patients: an update on evidence to assist clinical decision making Patients who still make urine tend to have fewer fluid restrictions, more dietary freedom, and lower inflammation markers. That makes daily life more manageable in ways that don’t always show up on a blood test.
What Residual Kidneys Do That Dialysis Cannot
The survival benefit isn’t just about extra fluid removal. Even a small amount of residual kidney function clears certain waste products that dialysis handles poorly. Standard dialysis is good at removing small molecules like urea. But protein-bound toxins, the kind that stick to proteins in your blood, are much harder for a dialysis membrane to pull out. Residual kidneys clear these bound solutes far more efficiently relative to their overall filtration rate. In hemodialysis patients, the residual kidneys removed a disproportionately large share of these protein-bound toxins compared to what you’d expect from their modest urea clearance alone.6PubMed Central. Contribution of residual function to removal of protein-bound solutes in hemodialysis A study in peritoneal dialysis patients found the same pattern: as dialysis duration increased, the kidneys’ percentage contribution to clearing these difficult solutes actually went up, because the kidneys were handling them so much better than the peritoneal membrane.7PubMed. Removal of middle molecules and protein-bound solutes by peritoneal dialysis and relation with uremic symptoms
Urine volume itself also correlates well with how much waste is being cleared. In peritoneal dialysis patients, urine output was strongly correlated with the mass of urea, creatinine, and phosphorus removed by the kidneys.2PubMed Central. Urine volume as an estimator of residual renal clearance and urinary removal of solutes in patients undergoing peritoneal dialysis So tracking your daily urine volume is a rough but useful window into how much your remaining kidneys are contributing.
Fluid Balance and What Happens When Output Drops
One of the most practical consequences of losing urine output is the effect on fluid management between dialysis sessions. Hemodialysis patients accumulate fluid between treatments, and the weight gained during that interval (interdialytic weight gain) is a risk factor for cardiovascular problems. A study of incident hemodialysis patients found that gaining 4% or more of body weight between sessions roughly doubled the risk of cardiovascular events. That risk was especially pronounced in patients with lower urine output, defined as below about 900 milliliters per day.8American Journal of Nephrology. Interdialytic Weight Gain and Cardiovascular Outcome in Incident Hemodialysis Patients
When your kidneys still produce urine, they help manage the fluid you take in between sessions, which reduces how aggressively the dialysis machine needs to pull fluid off during treatment. Rapid fluid removal during dialysis can cause blood pressure drops, cramping, and dizziness, and may itself accelerate the loss of remaining kidney function by reducing blood flow to the kidneys. It’s a feedback loop: losing urine output makes dialysis harder, and harder dialysis may speed the loss of whatever output remains.
What Drives the Decline in Urine Output
The kidneys’ remaining function doesn’t decline at the same rate for everyone, and the causes are a mix of the unavoidable and the modifiable. The underlying disease (diabetes, hypertension, glomerulonephritis) continues to damage kidney tissue whether you’re on dialysis or not. But several dialysis-related factors also play a role.
Repeated episodes of low blood pressure during dialysis sessions are a recognized contributor. When blood pressure drops sharply during treatment, blood flow to the kidneys falls, and over time this can injure the remaining functional tissue. Minimizing these hypotensive episodes is one of the practical strategies recommended for preserving residual function.9PubMed Central. Preservation of residual kidney function in hemodialysis patients: reviving an old concept Aggressive fluid removal during dialysis compounds the problem. Patients who needed higher ultrafiltration rates (meaning more fluid pulled off per session) were progressively less likely to recover kidney function, with the highest rates associated with less than half the odds of recovery compared to the lowest rates.10PubMed Central. Predictors of kidney function recovery among incident ESRD patients
Exposure to nephrotoxic substances, including certain contrast dyes used in imaging and some antibiotics, also accelerates the decline. Even the choice of dialysis membrane may matter, though the evidence on biocompatible versus older membranes is less definitive than for the factors above.
Incremental Dialysis as a Preservation Strategy
Standard hemodialysis in most countries means three sessions per week. But for patients who start dialysis with meaningful residual function, there’s growing interest in an incremental approach: beginning with two sessions per week and adding more only as kidney function declines. The logic is straightforward. If your kidneys are still contributing, you don’t need three full sessions worth of clearance from the machine, and subjecting the body to fewer sessions may be gentler on whatever kidney function remains.
A review of twelve observational studies found that incremental hemodialysis was associated with better preservation of residual function and longer usable life of vascular access sites.11PubMed Central. Incremental dialysis for preserving residual kidney function-Does one size fit all when initiating dialysis? A cohort study comparing incremental and conventional hemodialysis found that incremental patients retained about 15-16% more kidney clearance and urine volume at the second quarter of treatment, an advantage that persisted over subsequent quarters.12PubMed Central. Incremental Hemodialysis, Residual Kidney Function, and Mortality Risk in Incident Dialysis Patients: A Cohort Study
Incremental dialysis does require regular monitoring of residual function to ensure adequate clearance. If your kidneys decline faster than expected, your team needs to bump up the frequency promptly. This approach is more common in peritoneal dialysis programs and in certain countries (parts of Europe, for instance), while U.S. practice has traditionally defaulted to three-times-weekly hemodialysis from the start. That is slowly changing.
Medications That May Help
Two classes of blood pressure medications have shown the most consistent benefit for slowing the decline in residual function: ACE inhibitors (like ramipril) and angiotensin receptor blockers (ARBs, like valsartan). In peritoneal dialysis patients, a meta-analysis of randomized trials found that those treated with an ACE inhibitor or ARB retained significantly more residual kidney filtration at twelve months compared to those on placebo or other blood pressure drugs.13PubMed Central. Effects of ACEIs and ARBs on the Residual Renal Function in Peritoneal Dialysis Patients: A Meta-Analysis of Randomized Controlled Trials A randomized trial of ramipril in peritoneal dialysis patients showed that the drug group lost about two-thirds as much kidney filtration over a year as the control group.14PubMed. Effects of an angiotensin-converting enzyme inhibitor on residual renal function in patients receiving peritoneal dialysis. A randomized, controlled study Valsartan showed similar preservation of both kidney filtration and urine volume over two years in another trial.15American Journal of Kidney Diseases. Effects of an angiotensin II receptor blocker, valsartan, on residual renal function in patients on CAPD
Loop diuretics, especially furosemide at high doses, are sometimes used to boost urine volume in dialysis patients who still have some output. In peritoneal dialysis patients, high-dose furosemide increased urine volume and electrolyte excretion, though it didn’t change actual kidney clearance of urea and creatinine.16PubMed. Acute effects of high-dose furosemide on residual renal function in CAPD patients A pilot study in hemodialysis patients found that about a third met the target for increased urine output at five weeks on oral furosemide, but the response was variable and didn’t translate into measurable improvements in blood pressure or interdialytic weight gain.17Kidney International Reports. Clinical Research Efficacy, Safety, and Tolerability of Oral Furosemide Among Patients Receiving Hemodialysis: A Pilot Study In short, furosemide can squeeze out more fluid, but it doesn’t appear to make the kidneys filter waste better. Its value is mostly in easing fluid overload for patients who respond to it.
How Residual Function Is Actually Tracked
The standard method for measuring residual kidney function is a 24-hour urine collection, which is exactly as inconvenient as it sounds. You collect all urine produced in a day (typically a non-dialysis day for hemodialysis patients), measure the volume, and send it to the lab to calculate clearances of urea and creatinine. The average of those two clearances gives a reasonable estimate of remaining kidney filtration.18PubMed Central. Prognostic Value of Residual Urine Volume, GFR by 24-hour Urine Collection, and eGFR in Patients Receiving Dialysis
Because 24-hour collections are burdensome, there’s ongoing interest in developing blood-test-based alternatives that could estimate residual function without requiring the collection.19PubMed. Measuring residual renal function in dialysis patients: can we dispense with 24-hour urine collections? None of the proposed formulas have replaced urine collection in routine practice yet, but urine volume itself, measured simply by having the patient report how much they produce, correlates well enough with actual clearance that it serves as a practical screening tool. If your urine output drops noticeably, it probably means your residual function is declining, even if you haven’t done a formal collection recently.
When Patients Stop Making Urine Entirely
Many long-term hemodialysis patients eventually become anuric, producing no urine at all. This is not a medical emergency in someone on adequate dialysis. The machine takes over the job. But complete loss of urine output has consequences beyond fluid and waste management.
When the bladder goes unused for months or years, it can shrink and stiffen. Research has shown that bladder capacity and compliance decrease with longer dialysis duration, particularly in patients who have been anuric for an extended period.20PubMed. Reduction of cystometric bladder capacity and bladder compliance with time in patients with end-stage renal disease This matters most for patients who later receive a kidney transplant. A shrunken, poorly compliant bladder can cause urological complications after transplant, including difficulty emptying, infections, and problems with the connection between the new kidney’s ureter and the bladder.21PubMed. Atrophic bladder in long-term dialysis patients increases the risk for urological complications after kidney transplantation If transplantation is a possibility in your future, preserving even a trickle of urine output helps keep the bladder functional and avoids the need for bladder augmentation surgery before or after transplant.
Can Kidney Function Actually Recover After Dialysis Starts?
Most people assume that once dialysis begins, it’s permanent. That is true for the majority, but not for everyone. Among a large U.S. cohort of over 370,000 people who started hemodialysis, about 4.5% recovered enough kidney function to stop dialysis.10PubMed Central. Predictors of kidney function recovery among incident ESRD patients Recovery was most likely in patients whose kidney failure was caused by an acute injury rather than a long-standing chronic disease. Having a higher estimated kidney filtration rate at the time dialysis started and lower ultrafiltration rates during treatment were both associated with better chances of coming off dialysis.
A separate analysis identified additional predictors of recovery within 90 days: higher baseline kidney function before the hospitalization, higher hemoglobin before admission, younger age, and absence of chronic liver disease.22PubMed Central. Predicting Renal Recovery After Dialysis-Requiring Acute Kidney Injury Other characteristics associated with eventual recovery include having been started on dialysis urgently in a hospital setting without prior nephrology follow-up, which suggests many recovery cases were patients who probably had acute or subacute kidney injuries rather than true end-stage disease.23Journal of Urology and Renal Diseases. Is Renal Function Recovery and Discontinuation of Long Term Hemodialysis Possible in Patients with Presumed End Stage Kidney Disease? The Role of Toprak’s Kidney Care
For someone with confirmed chronic kidney disease who has been on dialysis for years with no urine output, recovery is extremely unlikely. But for patients who started dialysis in a crisis, especially if they still produce some urine, the possibility is worth discussing with your nephrologist. Regular monitoring of urine output and residual function gives you the information needed to spot a trend toward recovery rather than assuming the situation is fixed.
Pediatric Patients and Dialysis Adequacy
Children on dialysis present a different picture from adults. Growth, nutrition, bone development, and puberty all add layers of complexity that don’t apply to a 60-year-old. Dialysis prescriptions for children are adjusted to account for body size, metabolic rate, and the need to support normal development, and residual kidney function plays an outsized role in that calculation. A child who still makes urine may need a less intensive dialysis regimen, which in turn means fewer hours hooked up to a machine and more time for school and play. The principles of preserving residual function are the same as in adults, but the stakes around quality of life during formative years make it an especially high priority in pediatric nephrology programs.