What is the role of medical therapy in the dissolution of calculi in nephrolithiasis?

Updated: Jun 21, 2018
  • Author: Chirag N Dave, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
  • Print
Answer

Urinary calculi composed predominantly of calcium cannot be dissolved with current medical therapy; however, medical therapy is important in the long-term chemoprophylaxis of further calculus growth or formation.

Uric acid and cystine calculi can be dissolved with medical therapy. Patients with uric acid stones who do not require urgent surgical intervention for reasons of pain, obstruction, or infection can often have their stones dissolved with alkalization of the urine. Sodium bicarbonate can be used as the alkalizing agent, but potassium citrate is usually preferred because of the availability of slow-release tablets and the avoidance of a high sodium load. In patients with recurrent calcium stones and low urinary citrate levels, potassium citrate therapy should be offered. For patients with obstructing uric acid stones in the collecting system that do not require surgical intervention, a combination of alkalinization with tamsulosin can increase the frequency of spontaneous passage of distal ureteral uric acid stones as shown in one RCT for stones > 5 mm. [93]

The dosage of the alkalizing agent should be adjusted to maintain the urinary pH between 6.5 and 7.0. Urinary pH of more than 7.5 should be avoided because of the potential deposition of calcium phosphate around the uric acid calculus, which would make it undissolvable. Both uric acid and cystine calculi form in acidic environments.

Even very large uric acid calculi can be dissolved in patients who comply with therapy. Roughly 1 cm per month dissolution can be achieved. Practical ability to alkalinize the urine significantly limits the ability to dissolve cystine calculi.


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!