Discriminant functions in differential diagnosis of hypercalcaemia.

Abstract Since there is still no completely satisfactory method for the differential diagnosis of hypercalcaemia, a multivariate analysis of readily available biochemical data was investigated as a discriminating procedure. A fairly simple arithmetic treatment of the results for plasma inorganic phosphate, alkaline phosphatase, chloride, bicarbonate, and urea obtained from hypercalcaemic patients on admission to hospital led to diagnoses which coincided in 197 of 218 cases (90.4%) with the diagnosis reached after a long period of detailed clinical investigation. The two discriminant functions involved in the analysis may be determined accurately from nomograms and plotted on ordinary graph-paper, so that this guide to the diagnosis in any case of hypercalcaemia may be obtained quickly and simply in any centre. The discrimination may well be improved further by the inclusion of other simple tests such as the erythrocyte-sedimentation rate and more precise measures of renal function.