Urinary calculus. A new method of determination: preliminary data

Introduction: The visualization of reactions used for the identification and quantification of substances in the urinary calculus presents significant problems. Methods: We describe a new laboratory procedure for the determination of the urinary calculus. The detection of carbonates and the concentrations of calcium, phosphorus, magnesium, ammonium, uric acid (quantitative dosages carried out on COBAS 6000 analyzer of the Roche company) and oxalate and cystine (determinations adapted by us on the Siemens Viva E instrument) are entered in an Excel sheet to obtain the main possible urinary calculations (calcium oxalate, uric acid, ammonium urate, cystine, struvite, brushite, apatite, carbonate apatite) and more generally "calcium phosphate". The clinical chemistry determinations are similar to those used for the metabolic study carried out on the 24h-urine in which the photometric dosage of cystine with phosphotungstic acid, not being marketed, was built and adapted on Viva E analyzer. The use of the rapid quantitative method, with non-commercial sulfosalicylic acid, built in our laboratory, is particularly useful for the determination of oxalate in the calculation. Results: The software proposed converts all concentrations of the above mentioned analytes to mmoles/dL and, starting from struvite, the possible presence of calcium oxalate, ammonium urate and different calcium phosphate, determined according to the Ca/P ratio. Conclusions: The data obtained, especially if referring to concretions formed by several components, show good results when compared with the FTIR technique.