A wet chemistry method for the analysis of urinary calculi.

A procedure for the routine investigation of urinary calculi is described. The investigation scheme was based on existing methods in the routine laboratory for calcium(II), magnesium(II), phosphate and urate in serum. The substance content of oxalate was calculated as non-phosphate-bound calcium(II). Furthermore the test for cystine in urine was utilized. Two specially designed tests were used, one for carbonate apatite and one for verification of the presence of oxalate. The scheme was applied to 30 specimens of human origin. The sum of the mass fractions of identified and calculated components in the calculi was found to be 0.88 on the average (s = 0.05). Low values for this sum may serve as an indication of the presence of rare components that are not included in this analytical programme. A few calculi containing rare components required special methods for the investigation and are most conveniently investigated in a specialized laboratory using X-ray diffraction or infra-red spectrometry. In this paper, however, we describe wet chemistry methods, suitable for reliable cystine determinations and for oxalate in calculi containing, for example, brushite, where the calculated oxalate value is uncertain. These methods may be used as an alternative to the physical methods for many of the rare calculi.