Cowley D M, McWhinney B C, Brown J M, Chalmers A H
Department of Pathology, Mater Misericordiae Public Hospitals, South Brisbane, Queensland, Australia.
Clin Chem. 1989 Jan;35(1):23-8.
Studies in 24 recurrent oxalate stone-formers have shown that values for urinary calcium excretion for this group on at-home diets vary significantly (P less than 0.001) more than values for creatinine excretions. By placing stone-formers on controlled in-hospital diets and measuring their calcium excretions, we were able to predict probable outpatient hypercalciuria (greater than 7.5 mmol/day) with a sensitivity of 95% and a specificity of 95%. In this study, the renal loss of calcium during low-calcium diets was proportional to the absorptive hypercalciuria during high-calcium diets. Calcium loading experiments in fasted stone-formers and normal subjects indicated that citrate, at citrate:calcium molar ratios ranging from 0.12 to 1, stimulated urinary calcium excretion more than did calcium carbonate loading alone. In addition, citrate also significantly (P less than 0.05) increased the excretion of urinary oxalate by two normal subjects for a given load of calcium oxalate. Malabsorption of citrate and possibly other hydroxycarboxylic acids may thus predispose to oxalate nephrolithiasis by promoting calcium and oxalate absorption.
对24名复发性草酸钙结石患者的研究表明，该组患者在家饮食时尿钙排泄值的变化幅度显著大于肌酐排泄值（P小于0.001）。通过让结石患者采用医院控制饮食并测量其钙排泄量，我们能够预测门诊患者可能出现的高钙尿症（大于7.5 mmol/天），灵敏度为95%，特异度为95%。在本研究中，低钙饮食期间肾脏的钙流失量与高钙饮食期间的吸收性高钙尿症成正比。对禁食的结石患者和正常受试者进行的钙负荷实验表明，当柠檬酸与钙的摩尔比在0.12至1之间时，柠檬酸比单独的碳酸钙负荷更能刺激尿钙排泄。此外，对于给定负荷的草酸钙，柠檬酸也显著（P小于0.05）增加了两名正常受试者的尿草酸排泄量。因此，柠檬酸以及可能其他羟基羧酸的吸收不良可能通过促进钙和草酸的吸收而导致草酸钙肾结石。
