Infrared spectrometric analysis of endemic bladder stones in Niger.

The composition of 42 bladder stones from young children in Niger has been determined by infrared spectrometry. Nucleus and subsequent layers were analyzed separately. The major constituents of the stones were ammonium acid urate (AAU) and calcium oxalate monohydrate (COM). The nucleus consisted of nearly pure AAU in 17 stones (40%) and it was found to be the major constituent of the nucleus in 8 other stones (19%). Furthermore, it was present as a minor constituent of the center in another 9 stones (21%). In only 3 calculi (7%) the nucleus consisted of pure COM. This study suggests that (a) AAU is the initiating material for nucleation in this stone type in Niger, and (b) the incidence of endemic bladder stone disease is higher in Africa than previously reported.