Short answer: Kidney replacement therapy (KRT, historically called renal replacement therapy or RRT) can be lifesaving in severe acute kidney injury (AKI), but starting it earlier or delivering a more intensive dose has not been shown to improve survival when urgent indications are absent. Modern practice is individualized: guidelines support prompt KRT when life-threatening fluid, electrolyte, acid-base or uremic complications are present, while other cases depend on the whole clinical trajectory rather than a creatinine number alone.
Scope note: this article summarizes trials and guidelines; it is not nephrology or intensive-care advice. AKI severe enough to require KRT is a medical emergency managed by critical-care and nephrology teams, and treatment decisions require patient-specific clinical data.
What is kidney replacement therapy in acute kidney injury?
AKI is a sudden decline in kidney function. In severe cases the kidneys may no longer be able to control fluid balance, potassium, acid-base status or the accumulation of waste products. KRT temporarily replaces part of those functions while clinicians treat the underlying illness and wait to see whether kidney function recovers.
Common ICU modalities include intermittent hemodialysis, continuous kidney replacement therapy (CKRT/CRRT), and prolonged intermittent treatments such as SLED. They use different schedules and rates, but the goal is the same: achieve the fluid, electrolyte, acid-base and solute balance that the patient needs.
When should KRT be started?
The clearest indication is when AKI causes a problem that cannot safely wait.
KDIGO guidance states that KRT should be initiated emergently when there are life-threatening changes in fluid, electrolyte or acid-base balance. Examples in clinical practice can include refractory severe hyperkalemia, severe metabolic acidosis, pulmonary edema or fluid overload causing respiratory compromise, and serious uremic complications.
KDIGO also emphasizes that the decision should be based on the broader clinical context, potentially reversible complications and trends in laboratory values rather than a single blood urea nitrogen or creatinine threshold.
KDIGO guidance on dialysis for AKI.
Does starting dialysis earlier improve survival?
Not routinely.
The largest modern trial addressing this question was STARRT-AKI. More than 3,000 critically ill patients with severe AKI were randomized to an accelerated strategy, in which KRT was started soon after eligibility, or a standard strategy, in which clinicians generally waited unless conventional indications developed or AKI persisted.
At 90 days, mortality was essentially identical: 43.9% with accelerated initiation versus 43.7% with the standard strategy.
Among survivors, continued dependence on KRT at 90 days was more common in the accelerated group, 10.4% versus 6.0%. Adverse events were also more frequent with accelerated treatment.
The practical message is not “wait as long as possible.” It is that pre-emptive KRT simply because AKI is severe is not automatically better when no urgent indication is present. The patient’s trajectory, volume status, electrolytes, acid-base balance, catabolic load, comorbidities and likelihood of recovery all matter.
Does more intensive dialysis improve outcomes?
This was one of the major questions in the VA/NIH Acute Renal Failure Trial Network, or ATN, study.
The original design compared a more intensive strategy with a less intensive strategy by increasing the frequency of intermittent dialysis and increasing the effluent dose of continuous therapy.
The completed randomized trial found no survival advantage. Death by day 60 occurred in 53.6% of the intensive group and 51.5% of the less-intensive group. More intensive therapy also did not improve recovery of kidney function or nonrenal organ failure.
ATN trial: Intensity of renal support in critically ill patients with AKI.
The RENAL trial reached a similar conclusion for continuous therapy: increasing CRRT intensity beyond a standard dose did not improve mortality.
Current KDIGO guidance recommends delivering an effluent volume of about 20–25 mL/kg/hour for CRRT, while recognizing that a somewhat higher prescription may be needed to ensure that the delivered dose reaches that target.
Continuous or intermittent dialysis: which is better?
There is no single best modality for every ICU patient.
Continuous and intermittent therapies are generally treated as complementary options. Continuous KRT is commonly preferred when a patient is hemodynamically unstable because fluid and solute removal can occur more gradually. It is also often favored when acute brain injury or elevated intracranial pressure makes rapid fluid and osmotic shifts undesirable.
For a stable patient who needs rapid correction of a severe electrolyte abnormality, intermittent hemodialysis may be appropriate. SLED and other prolonged intermittent approaches occupy the middle ground and can be useful depending on staffing, equipment and patient physiology.
Importantly, trials have not established that continuous KRT universally improves survival or kidney recovery compared with intermittent KRT. The modality is selected mainly for the clinical situation and treatment goals.
Continuous Kidney Replacement Therapies: Core Curriculum 2025.
What do newer ICU guidelines say?
A 2025 multidisciplinary guideline from German and Austrian intensive-care societies produced 73 evidence-based statements covering when to start KRT, modality, anticoagulation, dose, drug treatment and stopping criteria.
Its overall direction is consistent with the major trial evidence: immediate KRT for life-threatening and refractory complications; otherwise an individualized strategy rather than automatic early treatment. Continuous or prolonged modalities are favored in hemodynamic instability, while the treatment dose and modality should be matched to the clinical goal.
2025 multidisciplinary ICU KRT guideline.
KDIGO is also updating its AKI guideline. A 2026 draft went through public review and includes revised sections on KRT timing, modality selection, dosing and discontinuation. As of September 2026, KDIGO states that the Work Group is preparing the final guideline for publication, so the draft should not be treated as the final recommendation set.
When can KRT be stopped?
KRT is stopped when native kidney function has recovered enough to maintain acceptable fluid, electrolyte, acid-base and metabolic balance without extracorporeal support.
There is no single laboratory number that proves readiness. Clinicians look at urine output, the trajectory of kidney function, fluid balance, potassium, acid-base status and whether the underlying illness is improving.
Recent ICU guidance identifies return of spontaneous urine output as one of the most useful practical signs when considering weaning, but the decision remains individualized.
Does stress or a psychological conflict cause acute kidney injury?
No evidence supports the claim that acute kidney injury, kidney cancer or Wilms tumor is caused by a psychological “territory conflict,” “feeling like a fish out of water,” or a healing phase after such a conflict.
An older version of this article repeated claims from German New Medicine that linked kidney-cell proliferation and acute renal failure to specific emotional conflicts. Those claims are not supported by renal physiology, pathology or clinical evidence and have been removed.
Psychological distress is nevertheless very real in severe kidney disease. Critical illness, ICU admission, dialysis, uncertainty and loss of independence can contribute to anxiety, depression and post-ICU psychological problems. Mental-health support can therefore be an important part of care, but it should not be confused with a causal explanation for AKI.
Bottom line
Kidney replacement therapy saves lives when severe AKI produces complications that the kidneys can no longer control.
But two intuitive ideas have not survived randomized testing:
Starting KRT earlier is not automatically better. In STARRT-AKI, accelerated initiation did not reduce mortality.
Giving a more intensive KRT dose is not automatically better. The ATN and RENAL trials found no survival benefit from higher-intensity strategies.
The modern approach is therefore individualized: treat urgent complications promptly, choose the modality that fits the patient’s physiology, deliver an evidence-based dose, and reassess continuously as kidney function and critical illness evolve.
References
1. KDIGO. Acute Kidney Injury and Acute Kidney Disease guideline resources.
2. VA/NIH Acute Renal Failure Trial Network. Intensity of renal support in critically ill patients with acute kidney injury. N Engl J Med. 2008.
3. STARRT-AKI Investigators. Timing of Initiation of Renal-Replacement Therapy in Acute Kidney Injury. N Engl J Med. 2020.
4. Continuous Kidney Replacement Therapies: Core Curriculum 2025.
5. Multidisciplinary guidelines on renal replacement therapy in intensive care medicine. 2025.