ADPKD

• Autosomal dominant polycystic kidney disease is a common genetic disorder characterised by multiple renal cysts
• Autosomal dominant polycystic kidney disease (ADPKD) is due to inheritance of the abnormal genes PKD1 or PKD2
• The disease is characterised by development of multiple renal cyst and progressive renal impairment, which leads to end-stage renal disease (ESRD) in around 50% of patients by 60 years of age. It accounts for up to 10% of patients with ESRD.
• Symptoms:

  • Abdominal, flank or back pain - due to large size or cyst complications (rupture/infection)
  • Haematuria - ruptured cyst
  • Dysuria and fever - suggestive or UTI or infected cyst
  • Renal colic - stones more common
  • Constitutional features of CKD
  • Polyuria, polydipsia and nocturia - excess urine due to poor concentrating ability e.g. not responding to anti-diuretic hormone
• Signs:

  • Bilateral flank masses
  • Hepatomegaly - if polycystic liver disease
  • Hypertension - seen in most patients
• Cyst complications:

  • Ruptured cyst
  • Haemorrhagic cyst - visible haematuria
  • Infected cyst
• Extra-renal manifestations:

  • Polycystic liver disease (>80% of patients)
  • Pancreatic cysts
  • Cerebral aneurysms
  • Cardiac valve disease - most commonly MR and AR
  • Diverticulosis and hernias more common
  • Seminal vesicle cysts and infertility
• Ultrasound and genetic testing are used for diagnosis
• The diagnosis of ADPKD is primarily made on imaging with identification of multiple bilateral renal cysts.
• Patients with a family history of ADPKD should be identified and offered screening. This involves investigating asymptomatic patients. 
• Bedside

  • Protein:creatinine ratio (ACR)
  • Urinalysis and MC&S: infection or haemorrhage
• Bloods

  • Full blood count: anaemia if CKD or haemorrhagic cysts
  • Urea & electrolytes: assessment of renal function
  • Liver function tests: any hepatic impairment from cysts
  • Bone profile: calcium/phosphate handling in CKD
  • CRP: infected cysts
• Imaging

  • Ultrasound: principle investigations, especially in screening
  • CT KUB: if presenting with suspected renal stone
  • Renal MRI/CT: high sensitivity and good for assessing progression (e.g. kidney size). Useful if concern regarding renal cell carcinoma (RCC)
  • Cerebral imaging (e.g. MRA): screening for cerebral aneurysms
• General management:

  • Blood pressure control essential (<130/80) - ACEi most effective
  • Regular renal function tests and USS
  • Maintain adequate hydration (unless CKD and overloaded)
• High risk patients:

  • Vasopressin receptor antagonists e.g. Tolvaptan
  • At risk of hypernatraemia
• If recurrent/concerns with haematuria - investigate for RCC
• treat urinary tract infections and infected cysts. Analgesia for abdominal pain or cyst rupture (avoid NSAIDs). Rarely, cyst decompression and/or nephrectomy may be needed if recurrent infections or pain that significantly impacts on quality of life
• Screening for cerebral aneurysms is generally reserved for patients with a personal or family history of intracerebral haemorrhage, patients who require anticoagulation (e.g. develop deep vein thrombosis), patients with high-risk occupations or patients needing major surgery (e.g. renal transplant). 
• MR angiography is the principle imaging tool for cerebral aneurysms (CT angiography if MRI contraindicated). Patients with small aneurysms may have sequential screening 2-3 yearly and those with no aneurysm 5-yearly.
• Complications:

  • ESRD
  • Massive cyst haemorrhage
  • Cerebral haemorrhage
  • Sepsis
  • progressive liver disease