Renal acidification defects in patients with recurrent calcium nephrolithiasis

Area of Science:

• Nephrology
• Urology
• Acid-Base Balance

Background:

• Recurrent calcium nephrolithiasis is a common condition.
• The role of renal tubular acidosis in stone formation is not fully understood.

Purpose of the Study:

• To evaluate the frequency of renal tubular acidosis in adult patients with recurrent calcium nephrolithiasis.
• To investigate the association between bicarbonate reabsorption defects and nephrolithiasis.

Main Methods:

• Studied 28 adult patients with recurrent calcium nephrolithiasis.
• Assessed renal bicarbonate reabsorption using fractional excretion of bicarbonate and TmHCO3/GFR.
• Evaluated urine pH and pCO2 to identify acidification defects.

Main Results:

• 42% of hypercalciuric patients had defective bicarbonate reabsorption.
• A proximal tubular defect in bicarbonate reabsorption was common in patients with calcium nephrolithiasis.
• This defect was associated with increased stone activity and mixed calcium oxalate and phosphate stones.

Conclusions:

• Defective tubular reabsorption of bicarbonate is highly prevalent in patients with calcium nephrolithiasis and hypercalciuria.
• Proximal acidification defects play a significant role in the pathogenesis of calcium nephrolithiasis.