Urinary tract stones at the University Hospital of the West Indies: a retrospective analysis

ABSTRACT

OBJECTIVE: To determine the proportional distribution in the composition of urinary tract stones seen at the University Hospital of the West Indies (UHWI). METHODS: Between July 1993 and October 1997, urinary tract stones submited to the chemical pathology laboratory at the UHWI for stone analysis by qualitative chemical methods were reviewed retrospectively. Demographic data recorded included the name, age, gender, hospital registration number, parish of origin of the patients and the date of receipt of the stone by the laboratory. Stone data recorded included the size, number and location of the stones within the urinary tract. The stones were analyzed for calcium, oxalate, phosphate, carbonate, uric acid, cystine and magnesium and each stone's composition was recorded under these headings. RESULTS: Mixed calcium oxalate stones accounted for 48.8 percent of cases seen, while pure calcium oxalate stones accounted for only 9.2 percent. Mixed uric acid and pure uric acid stones accounted for 32.8 percent and 4.6 percent of cases, respectively. Stones with calcium phosphate accounted for 56.5 percent of total cases, while pure calcium phosphate stones accounted for 6.1 percent. Struvite stones accounted for 15.3 percent of cases, of which 35 percent were mixed with uric acid. There was one cystine stone (0.8 percent of cases) and it was mixed with uric acid. CONCLUSION: The composition of urinary tract stones seen at the UHWI is quite different from that in other countries, with this series demonstrating a relatively high proportion of both pure and mixed calcium phosphate stones, mixed uric acid stone and relatively few calcium oxalate stones.(Au)