Kidney Stones

Overview of Kidney Stones in ADPKD

The prevalence of kidney stones in ADPKD patients is approximately 15-20%, significantly higher than in the general population (about 5-10%). Contributing factors include altered urinary tract anatomy due to cyst compression, urinary stasis, and metabolic abnormalities (such as low citrate excretion and hyperuricemia). Kidney stones can cause pain, hematuria, obstruction, and infection, all of which can worsen kidney damage — making prevention and management essential.

Stone Types

• Uric acid stones: Relatively common in ADPKD patients, associated with uric acid metabolism abnormalities and acidic urine
• Calcium oxalate stones: Also fairly common, related to dietary and metabolic factors
• Infection stones (struvite): Patients with recurrent urinary tract infections may develop magnesium ammonium phosphate stones
• Mixed stones: Some patients have stones composed of multiple materials

Common Symptoms

• Flank or back pain: May be dull ache or severe colic; pain may suddenly worsen when a stone moves
• Hematuria (blood in urine): Visible or microscopic blood in the urine, caused by the stone irritating the urinary tract lining
• Obstruction: A stone blocking the urinary tract can cause difficulty urinating or reduced urine output
• Associated infection: May present with fever, chills, and frequent, urgent, or painful urination
• No symptoms: Some small stones cause no noticeable symptoms and are discovered incidentally during imaging

Diagnostic Methods

• Non-contrast CT scan: The primary method for diagnosing kidney stones; shows stone size, location, and degree of obstruction
• Ultrasound: Radiation-free, useful for initial screening, but has limited sensitivity for small stones
• Abdominal X-ray: Can detect radiopaque stones, but will miss radiolucent stones such as uric acid stones
• Urinalysis: Evaluates hematuria and signs of infection
• Stone composition analysis: Passed or surgically retrieved stones can be analyzed to guide prevention
• Metabolic evaluation: Blood uric acid, 24-hour urine biochemistry, and other tests to assess underlying causes

Management Principles

Management of kidney stones should be evaluated by a urologist, with decisions based on stone size, location, symptoms, and kidney function. This page does not provide specific treatment plans — do not attempt to pass stones on your own.

• Conservative observation: Small, asymptomatic stones may be monitored with follow-up, arranged by your doctor
• Medication-assisted passage: Some stones may be helped to pass with medication, requiring a doctor's prescription
• Extracorporeal shock wave lithotripsy (ESWL): Suitable for certain qualifying stones, evaluated by a urologist
• Minimally invasive surgery: Such as ureteroscopic lithotripsy or percutaneous nephrolithotomy; cyst impact must be assessed
• Associated infection: Infection must be controlled before stone treatment; urgent situations require immediate intervention

Prevention Measures

Adequate Hydration

• Aim for 2-3 liters of fluid intake per day to maintain adequate urine output (at least 2 liters per day)
• Distribute fluid intake evenly throughout the day, including moderate amounts at night
• Patients with declining kidney function should follow their doctor's guidance on fluid intake to avoid excess

Uric Acid Control

• Patients with high uric acid levels should have their doctor assess whether uric acid-lowering treatment is needed
• Reduce high-purine foods: organ meats, seafood, rich meat broths
• Limit sugary drinks, especially those high in fructose

Low-Sodium Diet

• Aim for less than 5g of salt per day; reduce processed foods
• A low-sodium diet helps reduce urinary calcium excretion, lowering the risk of calcium oxalate stones

Other Prevention

• Adequate calcium intake: Do not blindly restrict calcium — dietary calcium helps bind oxalate in the gut
• Reduce high-oxalate foods: Such as spinach, strong tea, and chocolate — consume in moderation
• Citrate supplementation: Patients with low citrate excretion may be evaluated by their doctor for supplementation
• Regular follow-up: Patients with a history of stones should have regular imaging follow-up at intervals determined by their doctor

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