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Module 01

Why does cirrhosis cause renal failure?

Follow the circulation from increased intrahepatic resistance to portal hypertension, splanchnic vasodilation, effective arterial underfilling, neurohumoral activation and renal vasoconstriction.

Explore mechanismChange the physiologyEvidence & guidance

Clinical frame

The organising problem.

HRS-AKI is best understood as a severe circulatory phenotype arising in decompensated cirrhosis, often destabilised further by infection, inflammation, bleeding or other acute insults. Structural kidney injury may coexist.

Mechanism

Follow the haemodynamic story.

The classical arterial-underfilling pathway is the organising model. It remains clinically useful, but it is not the whole explanation for AKI in advanced cirrhosis.

Normal circulation

A low-resistance portal circuit

01 / 05
Splanchnic bednormal resistanceLiverlow resistanceArterial circulationadequately filledKidneysperfusion maintained
What changes?

Portal blood crosses the hepatic sinusoids and returns to the systemic circulation. Effective arterial volume and renal perfusion are maintained.

Mechanism

The liver receives a high-flow, low-pressure portal inflow while the systemic arterial circulation remains appropriately filled.

Clinical meaning

Use this state as the reference point: adequate mean arterial pressure does not require major neurohumoral compensation.

Beyond the classical model

HRS-AKI is not one pathway.

The arterial-underfilling model remains useful, but contemporary ICU physiology also has to account for systemic inflammation, cardiac reserve, venous congestion and overlapping structural kidney injury.

Haemodynamics

Arterial underfilling remains central

Portal hypertension and splanchnic vasodilation reduce effective arterial filling, driving RAAS and sympathetic activation, renal vasoconstriction and loss of renal autoregulatory reserve. This remains the physiological basis for vasoconstrictor therapy.

Inflammation

Systemic inflammation can amplify organ failure

Bacterial translocation, pathogen-associated molecular patterns and damage-associated molecular patterns can intensify endothelial dysfunction, nitric-oxide signalling, vasoplegia, immunopathology and metabolic stress. In advanced decompensation and ACLF, inflammation is not simply a precipitant sitting outside the haemodynamic model.

Congestion & reserve

Renal filtration can also fail from the venous side

Cirrhotic cardiomyopathy, right-sided pressure, tense ascites and intra-abdominal hypertension can raise renal venous or interstitial pressure and reduce the filtration gradient. Arterial underfilling and venous congestion can therefore coexist in the same patient.

These mechanisms are complementary rather than mutually exclusive. A patient can have HRS physiology, sepsis-associated vasoplegia, tubular injury and congestion at the same time.

Arroyo V, et al. J Hepatol. 2021;74:670–685 — systemic inflammation hypothesis ↗Velez JCQ, et al. Adv Kidney Dis Health. 2024;31:87–99 — contemporary HRS pathophysiology ↗
Change the physiology

Same creatinine rise. Different circulation.

Choose a physiological stressor and compare its effects with a compensated reference state.

Increase vasodilation. Splanchnic vasodilation progresses in a patient with ascites.

  1. 01

    Arterial filling

    ReferencePressure supported

    Selected scenarioEffective filling falls

  2. 02

    Renal vascular tone

    ReferenceAutoregulation available

    Selected scenarioVasoconstrictor drive rises

  3. 03

    Venous / tissue pressure

    ReferenceOutflow unobstructed

    Selected scenarioMay already be elevated

  4. 04

    Kidney response

    ReferenceFiltration maintained

    Selected scenarioFiltration can fall

Why this happens

Reduced arterial stretch drives sympathetic, renin–angiotensin–aldosterone and vasopressin responses. Sodium and water retention may worsen ascites without correcting the primary vasodilatory problem.

What to look for

Low arterial pressure and avid sodium retention can coexist with obvious extracellular fluid excess.

Limit of the model This explains a circulatory component of AKI. It does not establish HRS-AKI as the diagnosis.

Sources and context: ADQI–ICA consensus (2024) ↗CONFIRM trial (2021) ↗

Go deeper

Mechanisms beneath the model.

Open the topics you need. Keep several explanations visible to compare mechanisms.

Evidence key: Established: broadly supported. Nuanced: context affects interpretation. Evolving: evidence or definitions remain unsettled. These labels describe physiological certainty, not a formal GRADE rating.

01SinusoidStructural and dynamic resistance coexistEstablished

Cirrhotic portal hypertension is not purely scar-related. A potentially modifiable dynamic component sits on top of fixed architectural distortion.

  • Fibrosis and regenerative nodules distort vascular architecture.
  • Activated stellate cells acquire contractile behaviour.
  • Sinusoidal endothelial dysfunction reduces local vasodilator capacity.
Evidence and source context ↓
02KidneyHRS is more than ‘pre-renal AKI’Nuanced

The classic functional model remains useful, but modern ICU patients frequently have inflammation, tubular injury, congestion or sepsis layered on top of cirrhotic haemodynamics.

  • Renal blood flow falls as systemic dysfunction advances.
  • Creatinine is an imperfect marker in sarcopenic cirrhosis.
  • Biology and phenotype may sit on a continuum between functional and structural injury.
Evidence and source context ↓
03HeartCardiac reserve mattersEvolving

A hyperdynamic circulation can mask impaired cardiac reserve. Infection, vasopressors, TIPS or transplantation can expose systolic or diastolic limitations.

  • High resting cardiac output does not guarantee adequate reserve.
  • Venous congestion can worsen renal function.
  • Cirrhotic cardiomyopathy complicates a purely arterial-underfilling model.
Evidence and source context ↓
04VolumeEffective arterial filling is a functional stateEstablished

Total body water, circulating blood volume and effective arterial filling describe different things. Arterial baroreceptors respond to stretch and pressure; they do not measure ascites. A vasodilated circulation can therefore activate sodium-retaining systems even when extracellular fluid is already expanded.

  • Aldosterone promotes sodium retention; non-osmotic vasopressin release promotes water retention. Water retention out of proportion to sodium contributes to dilutional hyponatraemia.
  • The relevant question is whether an intervention improves perfusion at tolerable filling pressures. A rise in central pressure alone does not establish improved renal blood flow.
  • Oedema does not establish either fluid responsiveness or fluid tolerance. These require assessment in the current haemodynamic context.
ADQI–ICA consensus (2024) ↗
05InterpretationA creatinine rise is the output of several possible mechanismsNuanced

GFR depends on renal blood flow, glomerular pressure and the filtration barrier. Severe vasoconstriction can reduce filtration; high venous or interstitial pressure can oppose it; tubular injury may coexist. A single creatinine value cannot separate these processes.

  • Low muscle mass and reduced creatinine generation can make substantial renal dysfunction look modest in absolute terms. Follow change from baseline and urine output.
  • Improvement in arterial pressure without renal recovery should reopen the physiological differential, including congestion and structural injury.
  • The modern HRS-AKI framework allows overlapping kidney disease. It does not require a routine 48-hour albumin challenge in every patient.
ADQI–ICA consensus (2024) ↗
Interventions

What are we trying to change?

Therapy makes more sense when its physiological target is explicit. These are mechanism summaries, not prescribing guidance.

TargetEffective circulation / plasma expansion

Albumin

Can improve circulatory filling in selected contexts and is paired with vasoconstrictor therapy for HRS-AKI.

TargetVascular tone

Terlipressin / noradrenaline

Raise effective arterial pressure and counter severe vasodilation, with renal improvement in responders.

TargetAcute destabiliser

Treat precipitant

Reversing infection, bleeding or another insult may restore a fragile haemodynamic equilibrium.

TargetUnderlying liver failure

Transplantation

Removes the driver of advanced portal and systemic circulatory dysfunction.

Check your reasoning

Apply the mechanism.

Arterial pressure improves during HRS treatment, but oliguria persists and pulmonary congestion increases. Which interpretation best fits the physiology?
Common physiology traps

What not to conclude.

  • Equating ascites with intravascular volume excess.
  • Calling all AKI in cirrhosis HRS-AKI.
  • Using a single MAP value without considering trajectory, congestion and organ perfusion.
  • Assuming high cardiac output means normal cardiac function.
Take it to the bedside

Four things to keep.

  1. Portal hypertension begins with resistance but becomes a resistance-and-flow problem.
  2. Splanchnic vasodilation drives effective arterial underfilling despite total-body fluid excess.
  3. HRS-AKI is a severe circulatory phenotype, but ICU AKI is often mixed.
  4. Treatments work by changing the circulation while definitive correction requires recovery or transplantation.
Evidence & current guidance

Where the physiology meets current practice.

Clinical criteria and treatment recommendations change faster than core physiology. This layer keeps the module tied to current consensus and primary evidence.

2024 ADQI–ICA definition

HRS-AKI is a phenotype, not a mandatory 48-hour albumin test

The contemporary consensus defines HRS-AKI in cirrhosis with ascites using AKI criteria, failure to improve after adequate volume resuscitation when clinically indicated, and absence of a stronger alternative explanation as the primary driver. Structural kidney injury, proteinuria or pre-existing CKD do not automatically exclude an HRS component.

  • AKI: serum creatinine rise ≥0.3 mg/dL within 48 hours or ≥50% within 7 days, and/or urine output ≤0.5 mL/kg/h for ≥6 hours.
  • If volume depletion is present, response to adequate resuscitation should be assessed promptly — generally within 24 hours.
  • Routine albumin administration for 48 hours is no longer required simply to establish the diagnosis.
  • In ICU practice, HRS-AKI can coexist with tubular injury, sepsis-associated AKI, CKD or congestion.
Treatment physiology

Treat the circulation — but reassess the phenotype if the kidney does not respond

The 2024 consensus recommends vasoconstrictor therapy, with terlipressin first-line where appropriate, together with 20–25% albumin after HRS-AKI is established. Albumin is not a fixed-dose ritual: it should be adjusted to haemodynamic and volume status and stopped if overload develops.

  • Terlipressin dose escalation is guided by creatinine response; norepinephrine titration is guided in part by MAP response.
  • An increase in MAP without renal improvement should trigger renewed consideration of alternative or coexisting causes of AKI.
  • Transplantation remains the definitive treatment for the underlying syndrome in suitable patients.
  • Renal replacement therapy is supportive, not a treatment for the HRS mechanism itself.
Safety

More vasoconstriction and more albumin are not automatically better

Terlipressin can reverse HRS-AKI in some patients, but pulmonary oedema, respiratory failure and ischaemic complications matter — especially in advanced illness or volume overload. The clinical physiology therefore has to include preload, afterload, cardiac reserve and pulmonary consequences rather than treating HRS as a kidney-only problem.

  • The CONFIRM trial showed greater verified HRS reversal with terlipressin, but also more respiratory failure.
  • Volume status should be reassessed daily during albumin/vasoconstrictor therapy.
  • Cirrhotic cardiomyopathy and venous congestion can undermine a simple arterial-underfilling model.
Key sourcesPrimary guidance and landmark evidence
Reviewed 12 September 2026 · next scheduled review September 2027
Acute kidney injury in patients with cirrhosis: ADQI–ICA joint multidisciplinary consensus meetingNadim MK, et al. J Hepatol. 2024;81:163–183. doi:10.1016/j.jhep.2024.03.031.

Current consensus definition, diagnostic approach and treatment framework for AKI/HRS-AKI in cirrhosis.

View source ↗Terlipressin plus Albumin for the Treatment of Type 1 Hepatorenal SyndromeWong F, et al. N Engl J Med. 2021;384:818–828. doi:10.1056/NEJMoa2008290.

CONFIRM randomized trial: efficacy for HRS reversal and the important respiratory safety signal.

View source ↗Diagnosis, Evaluation, and Management of Ascites, SBP and Hepatorenal SyndromeBiggins SW, et al. Hepatology. 2021;74:1014–1048. doi:10.1002/hep.31884.

AASLD practice guidance providing the broader ascites/HRS clinical framework; some diagnostic details have since been updated by ADQI–ICA 2024.

View source ↗

Review policy: each module is reviewed at least annually and sooner after a major guideline, consensus statement or practice-changing study. A review date indicates editorial review, not that every linked source is open access.

Connect the mechanisms

Circulation

Portal pressure, varices & TIPS

What actually determines portal pressure — and what does TIPS change?

Explore module →Circulation

Cirrhotic cardiomyopathy

How can a high-output circulation hide cardiac dysfunction?

Explore module →
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