Chemolysis

Chemolysis is clinically employed in several specific scenarios within urological practice for the management of kidney stones:

Primary Treatment

Chemolysis serves as a primary treatment option for select patients with specific stone compositions, particularly uric acid stones.¹ Oral chemolysis through urinary alkalization is the standard approach for patients with uric acid calculi, as these stones are uniquely amenable to dissolution therapy.² The European Association of Urology (EAU) guidelines recommend oral chemolysis for uric acid stones but not for sodium or ammonium urate stones.³

Adjunctive Therapy

Chemolysis is frequently utilized as an adjunctive treatment following other stone removal procedures such as shock wave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL), or ureteroscopy.⁴ This approach helps dissolve residual stone fragments, thereby reducing the risk of stone recurrence and the need for additional interventions.⁵

Patient Selection Criteria

Candidates for chemolysis are selected based on several factors:

• Stone composition (primarily uric acid, certain phosphate stones)⁶
• Stone size and location⁷
• Patient’s overall health status and renal function⁸
• Presence of urinary tract infection (which may contraindicate certain approaches)⁹
• Previous treatment history and stone recurrence patterns¹⁰

Procedural Approaches

Chemolysis can be administered through different routes:

1. Oral chemolysis: Systemic administration of agents that alter urinary pH, typically used for uric acid stones.¹¹ This involves medications such as potassium citrate, sodium bicarbonate, or magnesium bicarbonate to achieve a target urinary pH of 6.5-7.2.¹²
2. Direct chemolysis: Local irrigation of dissolution agents directly to the stone via percutaneous nephrostomy tubes, ureteral catheters, or through endoscopic approaches.¹³ This method is more commonly used for phosphate-containing stones.¹⁴

Expected Outcomes

The effectiveness of chemolysis varies based on multiple factors:

• Complete dissolution rates for uric acid stones with oral chemolysis range from 40-60% after 3 months of treatment.¹⁵
• Factors associated with higher success rates include smaller stone size, lower stone density, and consistent maintenance of target urinary pH.¹⁶
• Partial dissolution is achieved in an additional 10-15% of cases, which may facilitate subsequent stone removal by other means.¹⁷

Complications and Limitations

Potential complications include:

• Sepsis (with direct chemolysis if proper sterile technique is not maintained)¹⁸
• Electrolyte imbalances¹⁹
• Systemic acidosis or alkalosis²⁰
• Mucosal irritation and bleeding (with direct chemolysis)²¹

The use of chemolysis requires careful monitoring, including regular assessment of urinary pH, renal function, and stone dissolution progress through imaging studies.²²