A small fraction of patients with nephrolithiasis form mixed stones containing calcium and uric acid or pass both calcium and uric acid stones; 23 of 539 patients we have studied fall in this category. These mixed stone formers tend to have unusually frequent stone recurrences. Although the patients are often considered to have a variant of uric acid nephrolithiasis, a high proportion harbor calcium as well as uric acid disorders. The usual treatment for uric acid lithiasis may fail to prevent calcium stone recurrence, unless concomitant calcium disorders are simultaneously corrected. Dual treatment may be very effective In preventing continued stone disease.
(Arch Intern Med 138:1090-1093, 1978)