Critical appraisal of oral calcium load test for indirect assessment of intestinal calcium absorption

Two methods of oral calcium load or tolerance test for the indirect assessment of calcium absorption were compared. In 16 patients in whom the diagnosis of absorptive hypercalciuria was made independently, an exaggerated urinary total calcium excretion during four hours following calcium load, indicative of increased calcium absorption according to the method of Pak et al., was found in 15 patients. An abnormally high increment in urinary calcium during third and fourth hours post-calcium load, suggestive of enhanced calcium absorption by the criteria of Broadus et al., was encountered in 14 patients. However, an exaggerated urinary total calcium following calcium load was found in all 7 patients with renal hypercalciuria, whereas only 4 were shown to have an enhanced increment in calcium excretion. It is concluded that both methods are equally reliable in the detection of increased calcium absorption in absorptive hypercalciuria. However, the technique of Broadus et al. is probably superior to that of Pak et al. in the disclosure of increased calcium absorption in renal hypercalciuria.