Polycystic Kidney Disease

Question 1

What are the genetics of autosomal dominant polycystic kidney disease (ADPKD)?

Answer 1

• 85% have mutations in PKD1 (chromosome 16) + reach end stage renal failure by 50s
• Mutation in PKD2 (chromosome 4) has slower course, reaching ESR by 70s

Question 2

How does ADPKD present?

Answer 2

• May be clinically silent unless cysts get bigger/bleed
• Loin pain
• Visible haematuria
• Cyst infection
• Renal calculi
• Hypertension
• Progressive renal failure

Question 3

How is ADPKD diagnosed?

Answer 3

• USS
• Renal cysts increase in prevalence with age, so diagnostic criteria AGE specific:
  
  • 15-39yrs = >3 cysts
  • 40-59yrs = >2 cysts in each kidney
• Liver (90% by age 50) and pancreatic cysts support diagnosis
• Screening for intracranial aneurysms (MRI) recommended for age < 65yrs if personal/FHx of aneurysm or subarachnoid haemorrhage

Question 4

What is the treatment for polycystic kidneys?

Answer 4

• Water intake 3-4L/day (if eGFR >30) may suppress cyst growth
• HTN target < 130/80: (1) ACEi/ARB, (2) thiazide, (3) beta-blocker
• Plan for renal replacement therapy including pre-emptive transplantation
• Tolvaptain (vasopressor antagonist) if:
  
  • CKD stage 2 or 3 at start of treatment
  • evidence of rapidly progressing disease
  • company provides it with the discount agreed in the patient access scheme