Analysis of urinary calculi formed by Nigerians

50 stones formed by Nigerians were analysed using a combination of qualitative chemical analysis, and petrographic analysis with the Reichert Model NR 333 254, polarization microscope. The Bausch and Lomb binocular dissecting microscope was used for macroscopic examination of the specimens and for taking samples from the 'nucleus', inner and outer surfaces of the stones, for analysis. The results showed that calcium phosphate and magnesium ammonium phosphate accounted for 64% of the stones, calcium oxalate for 28% while uric acid accounted for 8%. This is in contrast to modern times Caucasian stones which are predominantly calcium oxalate. There appears to be a greater tendency for Nigerians to form large staghorn calculi than small stones that can passed spontaneously. The phosphate stones are known to be related to infection in the urinary tract. The findings on the composition of these calculi correlate with the previous findings of a high incidence of obstruction and infection in Nigerian patients with urinary calculi.