PA27.12-13 | Cystic Kidney Disease, Renal Stones & Obstructive Uropathy — Summary & Reflection

REFLECT

Take five minutes to answer these without looking back:

1. List three extrarenal manifestations of ADPKD and identify which carries the highest mortality risk.
2. Why is struvite stone formation self-perpetuating without surgical intervention?
3. A patient with a long-standing partial ureteric obstruction now has a serum creatinine of 4.2 mg/dL. Which histological features explain the impaired function, and is it reversible?

Compare your answers to the preceding sections. Identify the one concept you found hardest to articulate — that gap is your revision priority before the MCQ assessment.

KEY TAKEAWAYS

Cystic Kidney Disease
- ADPKD (PKD1/PKD2, AD) — adult onset, bilateral massively enlarged kidneys, berry aneurysms/SAH + hepatic cysts + MVP extrarenally; ESRD by 5th–6th decade.
- ARPKD (PKHD1, AR) — perinatal/infantile, sponge-like collecting duct cysts, congenital hepatic fibrosis, Potter sequence in severe forms.
- Simple cysts — sporadic, benign; acquired cysts (dialysis) — ↑RCC risk.

Renal Stones
- Calcium oxalate/phosphate (70–80%, radiopaque, hypercalciuria/hyperoxaluria)
- Struvite (urease bacteria, staghorn, alkaline urine, radiopaque)
- Uric acid (gout, acid urine, radiolucent, dissolve with alkalinisation)
- Cystine (cystinuria, AR, hexagonal crystals, childhood onset)

Obstructive Uropathy
- Back-pressure → tubular ischaemia → atrophy → interstitial fibrosis → cortical thinning → ESRD if prolonged.
- Complications: pyelonephritis/pyonephrosis, AKI/CKD, stones, hypertension, post-obstructive diuresis.
- Commonest causes: stones (young adults), BPH (older men), PUJ obstruction (children).