Risk Factors in Calcium Stone Disease of the Urinary Tract

Summary— The concept that calcium stone formation may be explained on the basis of a number of risk factors is developed. The main risk factors involved are shown to be calcium, oxalate, pH, acid mucopolysaccharides and uric acid. A method is described for calculating and combining the individual risk factors into a measure of the “relative probability” of forming stones (P SF ). P SF values are generally lower in normal subjects than in stone‐formers. Amongst the normals, P SF values are lower in children and women than in men. Recurrent stone‐formers have the highest P SF values and these correlate well with the severity of the disease as defined by the stone episode rate of the patient. Single stone‐formers have P SF values intermediate between those of normal men and those of recurrent stone‐formers.