STRUVITE STONES - LONG-TERM FOLLOW-UP UNDER METAPHYLAXIS

This study presents the results of a 10-year metaphylaxis of 19 former struvite stone formers, each having had 2-3 stone operations. In thes e patients, urine was acidified with L-methionine (Acimethin(R)) using a dose of three to six tablets 500 mg/day. Every three months, 11 lab oratory parameters were checked in 24-hour urine. 6 parameters were de termined in serum. In addition, urine samples were tested for infectio n. Statistical analysis of analytical data, which was supported by com puter graphs, provided the results for the urinary parameters. They we re described by geometric means and 95% confidence intervals using ANO VA (analysis of variance). During therapy, the mean pH values decrease d significantly from 7.5 to 5.5. Significant increases were found in t he excretion of citrate, magnesium, potassium and uric acid. An increa se was also found for calcium, which, however, could not be confirmed to be statistically significant (p = 0.08). In serum, changes of param eters could only be registered for calcium and phosphate. However, at all times, total serum concentrations stayed within their normal limit s. Three patients suffered occasional infections (16 %), only two of t hem formed recurrent stones (10 %). In assessing the efficacy of L-met hionine therapy, the drop in urinary pH to acidic values was the most relevant factor for metaphylaxis.