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ukmla 2026

Polycystic Kidney Disease

Autosomal dominant (ADPKD) or recessive inherited disorder characterised by progressive bilateral renal cyst development, leading to renal enlargement and ESRD — the commonest inherited cause of kidney failure

Review date
reviewed 2026-04-05
Reading time
5 min read
Author
Dr Kola Tytler MBBS CertHE MBA MSt MRCGP
Renal & Urologyless-commonchronic
On this page
Condition details
Renal & Urology
less-common
5 min read
reviewed 2026-04-05
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About This Page

This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.

Key points

  • ADPKD: autosomal dominant, commonest inherited renal disease (~1 in 1000). PKD1 (chromosome 16, ~85% — more severe) or PKD2 (chromosome 4, ~15% — milder)
  • Progressive bilateral renal cyst growth → massively enlarged kidneys → ESRD (median age ~55 for PKD1, ~75 for PKD2)
  • Extrarenal manifestations: hepatic cysts (~70%), intracranial (berry) aneurysms (~8%), mitral valve prolapse, colonic diverticulae
  • Diagnosis: USS showing bilateral renal cysts (age-dependent criteria). Genetic testing if USS equivocal or family planning
  • Tolvaptan (vasopressin V2 receptor antagonist): slows cyst growth and renal function decline in rapidly progressing ADPKD (NICE-approved)

Overview

Autosomal dominant polycystic kidney disease (ADPKD) is the commonest inherited renal disorder, caused by mutations in PKD1 (85%, encoding polycystin-1) or PKD2 (15%, encoding polycystin-2). These transmembrane proteins are involved in cell signalling and tubular morphogenesis. Mutations lead to unregulated tubular cell proliferation, fluid secretion into cysts, and progressive cyst growth. Kidneys can become massively enlarged (>20 cm). The disease is slowly progressive, with most patients maintaining normal renal function until their 30s-40s, with median age of ESRD at ~55 years for PKD1. Autosomal recessive PKD (ARPKD) is much rarer, presents in infancy/childhood, and is caused by PKHD1 mutations.

Epidemiology

ADPKD has a prevalence of approximately 1 in 400–1000 and accounts for ~7–10% of patients on dialysis/transplant. It is the fourth most common cause of ESRD in the UK. The condition is fully penetrant (all carriers develop cysts), although severity varies between PKD1 and PKD2. Approximately 10% of cases arise from de novo mutations (no family history). Intracranial aneurysms occur in ~8% (compared with 2% in the general population), with risk of subarachnoid haemorrhage.

Clinical Features

Symptoms
Often asymptomatic until 30–50 years (detected on screening or incidentally)
Flank or abdominal pain (cyst expansion, haemorrhage, or infection)
Visible/palpable abdominal mass (enlarged kidneys)
Haematuria (cyst haemorrhage or rupture)
Hypertension (often the earliest clinical manifestation — affects 60% by age 30)
UTIs and infected cysts
Renal colic (stones form in ~20% due to urinary stasis)
Subarachnoid haemorrhage (ruptured berry aneurysm)
Signs
Bilateral ballottable kidneys (massive, irregular palpable kidneys)
Hypertension
Hepatomegaly (hepatic cysts — present in ~70% but rarely symptomatic)
Signs of CKD in advanced disease

Investigations

First-line
Renal ultrasoundDiagnostic: bilateral renal cysts. Unified Ravine criteria (age-dependent): e.g. ≥3 cysts total in at-risk individual aged 15–39. Kidneys typically enlarged with multiple cysts
U&Es, eGFRMonitor renal function — may be preserved until late in the disease
Blood pressureHypertension is common and should be treated aggressively (target <130/80 mmHg)
Second-line
MRI kidneys (total kidney volume)Prognostic — total kidney volume (TKV) predicts rate of progression. Used to assess eligibility for tolvaptan
Genetic testing (PKD1/PKD2)If USS equivocal, family planning, potential living kidney donation from at-risk relative, or very early-onset disease
Specialist
MRA brain (intracranial aneurysm screening)Offer MRA to patients with family history of intracranial aneurysm or SAH. Not routinely screened in all ADPKD patients (controversial — discuss with patient)
UrinalysisHaematuria (cyst haemorrhage), proteinuria (progressive disease)

Management

NICE TA877 (Tolvaptan for ADPKD) and UK Kidney Association Guidelines
1
Blood pressure control
  • Target <130/80 mmHg (HALT-PKD trial)
  • First-line: ACEi or ARB (also reduces proteinuria)
  • Early aggressive BP control slows cyst growth and renal function decline
2
Tolvaptan
  • Vasopressin V2 receptor antagonist: inhibits cAMP-driven cyst growth and fluid secretion
  • NICE-approved for ADPKD with rapidly progressing disease (eGFR 25–65, evidence of rapid progression by TKV or eGFR decline)
  • Slows eGFR decline by ~1 mL/min/year and reduces TKV growth
  • Side effects: polyuria, polydipsia, nocturia (aquaretic effect), hepatotoxicity (monitor LFTs monthly for 18 months then 3-monthly)
  • Patients must maintain high fluid intake and have access to water at all times
3
Complication management
  • Cyst infection: lipophilic antibiotics that penetrate cyst wall (ciprofloxacin, trimethoprim) — standard beta-lactams do not penetrate well
  • Cyst haemorrhage: usually self-limiting (bed rest, analgesia, hydration). Avoid anticoagulants during acute episode
  • Renal stones: manage per standard stone guidelines
  • Pain: avoid NSAIDs (nephrotoxic). Paracetamol, weak opioids, consider renal denervation or cyst aspiration for severe pain
4
Renal replacement therapy
  • When ESRD reached: haemodialysis, peritoneal dialysis, or kidney transplant
  • Transplant is treatment of choice — may require bilateral nephrectomy if kidneys too large for transplant space
  • Living donor assessment: screen at-risk relatives with USS ± genetic testing

Complications

  • ESRD: Median age ~55 for PKD1, ~75 for PKD2. Accounts for 7–10% of dialysis patients
  • Intracranial aneurysm and SAH: ~8% have berry aneurysms. Family history of SAH increases risk further. Screen with MRA
  • Cyst infection: Difficult to treat — requires lipophilic antibiotics that penetrate cyst wall
  • Cyst haemorrhage: Presents with acute flank pain ± visible haematuria
  • Renal stones: ~20% — from urinary stasis within distorted collecting system
  • Hepatic cysts: ~70% of ADPKD patients. Rarely symptomatic unless massive
UKMLA Exam Tips
  • 1ADPKD = autosomal DOMINANT, PKD1 (chr 16, severe) and PKD2 (chr 4, milder). ARPKD = autosomal RECESSIVE, presents in infancy
  • 2Bilateral ballottable kidneys = ADPKD until proven otherwise
  • 3Intracranial berry aneurysms: screen with MRA if family history of SAH/aneurysm. Not all ADPKD patients are screened
  • 4Tolvaptan: aquaretic (massive polyuria) — patients MUST drink large volumes of water. Monitor LFTs for hepatotoxicity
  • 5Cyst infection: use ciprofloxacin or trimethoprim (penetrate cyst wall). Beta-lactams do NOT penetrate cysts well
  • 6ADPKD is the commonest INHERITED cause of ESRD

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Verified Sources & References

NICE TA877 — Tolvaptan for ADPKD
UK Kidney Association ADPKD Guidelines
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