Quadric analysis in the preoperative distinction between patients with and without adrenocortical tumors in hypertension with aldosterone excess and low plasma renin

Retrospective assessment by means of computer-assisted quadric analysis of a series of 31 patients with aldosterone excess and low plasma renin permitted complete separation into two groups—those with, and those without adrenocortical adenoma. Application of these principles to 8 more patients was successful in all cases in correctly diagnosing the type of pathological lesion before operation. Study of four similar published series has shown that each of these could also be accurately differentiated into the two diagnostic categories by quadric analysis. However, probably because of interlaboratory variation, internal analysis using circumscribing quadrics established for each series individually was much more reliable than external analysis with reference to the quadrics of the original series. Quadric analysis, by enabling a confident prediction to be made before operation as to the presence or absence of an adrenocortical adenoma, has major value in the practical management of these patients. In particular, in the cases without adenoma, long-term or definitive spironolactone therapy may now be offered as a valid alternative to extensive bilateral adrenal resection. It is further suggested that the technique of quadric analysis is likely to have wide application in other diagnostic areas.