Easy-to-use equations for the estimation of urine relative saturation in the assessment of risk of recurrence in urinary stones formers

It is a fact that recurrence of urinary stones is a common medical problem. One of the key factors used in determining the risk of urinary stone-formation is the urine relative saturation in the major constituents of lithiasis. Nomograms were developed in the 1970's to estimate the relative saturation of urine. We present here easy-to-use mathematical equations derived from these nomograms. These equations can be integrated directly in the LIS of any laboratories, and can be used as a tool in the treatment and prevention of recurrent stone-formation. •Mathematical equations were derived from nomograms developed by Marshall et al.•These equations can be integrated directly in the LIS of any laboratories.•These equations prevent mistakes associated with the use of the nomograms.•These equations can be use in the treatment/prevention of recurrent stone-formation.