The composition of catheter encrustations, including the effects of allopurinol treatment.

The composition of encrustations precipitated on long-term indwelling urethral catheters was analysed using a newly developed wet chemical method that allows determination of small sample volumes. In contrast to earlier studies, the major portion of the encrusted material could be identified; ammonium magnesium phosphate and calcium phosphates (brushite and apatite) were the major components. The effect of allopurinol was also investigated and it was found to decrease significantly the amounts of urate and calcium phosphate but not to lower significantly the total amount of material precipitated on the catheters.