Does the presence of kidney stones constitute kidney damage in the context of Chronic Kidney Disease (CKD)?

Does the Presence of Kidney Stones Constitute Kidney Damage in CKD?

The presence of kidney stones does not automatically constitute kidney damage in the context of CKD, but there is emerging evidence linking nephrolithiasis to increased risk of CKD development and progression. 1

Understanding the Relationship Between Stones and CKD

The distinction between kidney stones as a risk factor versus actual kidney damage is critical:

• Kidney stones themselves are not classified as structural kidney damage in the traditional definition of CKD, which requires abnormalities present for >3 months with health consequences 1

• However, the 2025 EAU guidelines explicitly state there is emerging evidence linking nephrolithiasis to the risk of chronic kidney disease 1

• Stone-related risks arise from obstruction, infection, genetic conditions, metabolic disorders, and urological treatments, all of which may impact renal function 1

When Stones Indicate or Cause Kidney Damage

Stones can lead to actual kidney damage through several mechanisms:

• Recurrent kidney stones predispose to CKD and CKD progression, as demonstrated in multiple epidemiological studies 2

• In patients with cumulative stone size <20 mm, each 1-mm increase in stone size is associated with a 20% increased risk of having CKD (OR 1.24,95% CI 1.02-1.52) 3

• Stone formers show markers of renal injury in urine even when asymptomatic, and direct evidence of renal tissue injury on histopathology 4

• Following kidney donation, stone disease in the remaining kidney could have serious consequences, including acute kidney injury from obstructive nephropathy and severe pyelonephritis 1

Clinical Assessment Framework

When evaluating whether stones constitute damage in a CKD patient:

1. Assess for structural abnormalities on imaging (hydronephrosis, renal scarring, nephrocalcinosis) which would qualify as CKD-defining kidney damage 1

2. Measure proteinuria/albuminuria - abnormalities in urine composition are markers of kidney damage independent of stone presence 1

3. Calculate eGFR - GFR <60 mL/min/1.73 m² for ≥3 months defines CKD regardless of whether kidney damage is present 1

4. Evaluate stone burden - cumulative stone size, number, location, and recurrence pattern correlate with degree of renal dysfunction 3

5. Consider stone composition - certain stone types (cystine, infection stones, genetic causes) have higher pathogenic potential for kidney injury 1, 4

Important Clinical Pitfalls

Common mistakes to avoid:

• Do not dismiss the long-term CKD risk in recurrent stone formers - stones should be prevented not only for immediate symptoms but also for their predisposition to CKD progression 2

• Do not assume all stone formers have the same risk - renal function varies by stone type, with genetic abnormalities like cystinuria and primary hyperoxaluria contributing significantly to disease burden 4

• In the general population with stone disease, there is significant risk of stone recurrence and patients may have increased risk of CKD and kidney failure 1

• Holistic evaluation should always consider CKD, end-stage kidney disease (ESKD), and metabolic bone disorder when assessing stone-related risks 1

Practical Implications

For risk stratification:

• Patients with nephrocalcinosis have higher risk of kidney failure after adjustment for stone numbers 1

• The number of stones alone does not correlate with kidney function over time or risk of kidney failure 1

• Stone formers with cumulative stone size up to 20 mm show linear decline in eGFR with increasing stone size 3