Pathophysiology
Mechanism
- Portal hypertension → splanchnic vasodilation (NO mediated)
- Effective arterial blood volume falls
- Activation of RAAS, SNS, ADH
- Intense intra-renal vasoconstriction
- Reduced renal blood flow → AKI without structural damage
KEY: The kidneys are histologically normal. If transplanted into a non-cirrhotic recipient, an HRS kidney functions normally.
Precipitants
- Spontaneous bacterial peritonitis (SBP) — commonest
- GI bleed (variceal)
- Large-volume paracentesis WITHOUT albumin cover
- Sepsis (any source)
- Aggressive diuresis
- Nephrotoxins (NSAIDs, contrast, aminoglycosides)
Who's At Risk
- Cirrhosis with ascites (especially refractory)
- Low MAP
- Hyponatraemia
- High Child-Pugh / MELD scores
Diagnosis
INTERNATIONAL CLUB OF ASCITES (ICA) CRITERIA — HRS-AKI: 1. Cirrhosis with ascites 2. AKI per KDIGO (rise in creatinine ≥26 µmol/L in 48 h or ≥50% within 7 days) 3. No improvement after 48 h diuretic withdrawal AND albumin challenge (1 g/kg/day, max 100 g) 4. No shock 5. No nephrotoxin exposure 6. No macroscopic structural kidney disease (USS normal, no proteinuria, no haematuria)
Investigations
- Bloods: U&E, LFT, FBC, clotting, lactate, ammonia, ABG
- Septic screen — blood + urine + ascitic fluid (DIAGNOSTIC PARACENTESIS in every cirrhotic with AKI to look for SBP)
- Urine: ACR (usually <50 mg/mmol), microscopy (bland sediment)
- Renal ultrasound (normal-sized kidneys, no obstruction)
- Echocardiogram if cardiac involvement suspected (cirrhotic cardiomyopathy)
- Consider: ANA, complement, cryoglobulins if features of underlying GN
Differential
- Pre-renal AKI (volume responsive)
- Sepsis-induced ATN (doesn't respond to albumin challenge)
- Drug-induced AIN
- Cardiorenal syndrome (cirrhotic cardiomyopathy)
- IgA nephropathy (common in cirrhosis)
- Cryoglobulinaemic GN (hep C)
- HBV-related membranous
Kidney Vitality is a daily multivitamin developed by a UK Consultant Nephrologist using renal nutrition principles. It contains no added potassium, magnesium, phosphorus or iron, and no herbal blends. See the formulation.
Treatment
General
- ICU/HDU level care
- Stop diuretics + beta-blockers if hypotensive
- Stop NSAIDs, nephrotoxins, ACE/ARB
- Manage encephalopathy (lactulose, rifaximin)
- Cover sepsis broadly while results awaited
- Cautious fluid replacement — albumin preferred over crystalloid
Specific Treatment
1. Iv Albumin
- 20% human albumin, 1 g/kg on day 1 (max 100 g)
- Then 20-40 g/day
- Continue for duration of vasoconstrictor therapy
2. VASOCONSTRICTOR (in addition to albumin):
- TERLIPRESSIN (UK first-line):
- 1-2 mg IV every 4-6 h (or continuous infusion 4-12 mg/24 h)
- Aim for MAP rise ≥10 mmHg, creatinine fall
- Continue for up to 14 days or until creatinine improves
- Side effects: ischaemic (digital, mesenteric, cardiac), pulmonary oedema (CONFIRM trial), hyponatraemia
- Avoid in significant cardiac/peripheral vascular disease
- NORADRENALINE (alternative in ICU):
- Continuous infusion titrated to MAP
- Useful if terlipressin contraindicated
- MIDODRINE + OCTREOTIDE (lower-resource setting): less effective
3. Renal Replacement Therapy
- Bridge to liver transplant or recovery
- Continuous (CVVHDF) better tolerated than intermittent in unstable patients
- Not curative without liver therapy
4. TIPS (transjugular intrahepatic portosystemic shunt):
- Considered in HRS-NAKI with refractory ascites
- Avoid in encephalopathy, severe liver dysfunction
5. Liver Transplant
- Definitive cure
- Combined liver-kidney transplant if HRS prolonged >4 weeks or pre-existing CKD
- Refer early — UK transplant centres prioritise via MELD-Na score
Prevention
Albumin Cover For Paracentesis
- Any large-volume tap (>5 L) — give 8 g albumin per litre removed
- Significantly reduces post-paracentesis circulatory dysfunction and HRS
Sbp Management
- Treat promptly with cefotaxime or piperacillin-tazobactam
- Add IV albumin 1.5 g/kg day 1 + 1 g/kg day 3 — reduces HRS incidence (Sort study)
- Long-term prophylactic norfloxacin/ciprofloxacin to prevent recurrence
Non-selective Beta-blockers
- Reduce variceal bleeding risk but withhold if hypotensive or in established HRS
Avoid Nephrotoxins
- NSAIDs absolutely contraindicated
- IV contrast — minimise, hydrate
- Aminoglycosides — avoid unless no alternative
- Cautious ACE/ARB — risk hypotension
Multidisciplinary Care
- Hepatology + Nephrology + Transplant team
- Early discussion if first AKI episode in cirrhosis
- Frailty assessment, nutrition, vaccination, prehabilitation
- Realistic conversations about prognosis and ceiling of care if transplant ineligible
