Polycystic Kidney Disease

Question 1

Definition

Answer 1

Autosomal dominant inherited disorder characterised by the development of multiple
renal cysts that gradually expand and replace normal kidney substance, variably
associated with extrarenal (liver and cardiovascular) abnormalities

Question 2

Aetiology

Answer 2

• 85% caused by mutations in PKD1 on chromosome 16
o This is a membrane-bound multidomain protein involved in cell-cell and cellmatrix interactions

• 15% caused by mutations of PKD2 on chromosome 4

Question 3

Pathophysiology

Answer 3

o Proliferative/hyperplastic abnormality of the tubular epithelium

o Early on, the cysts are connected to the tubules from which they arise and the fluid content is glomerular filtrate
o When cyst diameter >2 mm, they detach from the tubule and the fluid content is derived from secretion of the lining epithelium
o With time, the cysts enlarge and cause progressive damage to adjacent functioning nephrons

Question 4

Epidemiology

Answer 4

• MOST COMMON inherited kidney disorder

* Responsible for 10% of end-stage renal failure

Question 5

Presenting symptoms

Answer 5

• Present at 30-40 yrs
• 20% have no family history
• May be asymptomatic

• Flank Pain - may result from cyst enlargement/bleeding, stone, blood clot migration,
infection

• Haematuria
• Hypertension
• Associated with berry aneurysms and may present with subarachnoid haemorrhage

Question 6

Signs on physical examination

Answer 6

• Abdominal distension
• Enlarged cystic kidneys
• Palpable liver
• Hypertension
• Signs of chronic renal failure (at late stage)
• Signs of associated AAA or aortic valve disease

Question 7

Investigations

Answer 7

US or CT

o Will show multiple cysts bilaterally in enlarged kidneys
o Liver cysts may also be seen