Muldowney F P, Freaney R, Ryan J G
Q J Med. 1980 Winter;49(193):87-94.
A standard oral calcium loading test has been employed in a group of idiopathic hypercalciuria (IH) subjects and in a group of marginally hypercalcaemic subjects with primary hyperparathyroidism (PHPT) in whom the diagnosis was revealed by careful combined measurements of serum ionized calcium and immuno-reactive parathyroid hormone (iPTH). Initial values for serum ionized calcium and creatinine clearance were similar in IH and in a control group of normal subjects, whereas iPTH levels were normal or low. Following oral loading, serum ionized calcium rose to similar levels in both IH and control subjects, with no suggestion of relative hypercalcaemia due to a postulated intestinal hyperabsorption in the IH group. A renal tubular calcium 'leak' was however clearly evident in the IH group, in both the fasting and post-absorptive phase. In the marginally hypercalcaemic PHPT subjects on the other hand, a relative post-absorptive hypercalcaemia was clearly apparent, as well as a gross renal tubular calcium leakage. Thus careful preliminary separation of masked PHPT from IH subjects is an essential step before evaluation of response to oral calcium challenge in stone-forming subjects. When this is done, no evidence of a relative post-absorptive hypercalcaemia can be seen in the residual IH group, and hypercalciuria appears to be 'renal' rather than 'absorptive' in origin.
对一组特发性高钙尿症（IH）患者和一组原发性甲状旁腺功能亢进症（PHPT）的轻度高钙血症患者进行了标准口服钙负荷试验，后者的诊断是通过仔细联合测量血清离子钙和免疫反应性甲状旁腺激素（iPTH）得出的。IH患者与正常对照组的血清离子钙初始值和肌酐清除率相似，而iPTH水平正常或偏低。口服钙负荷后，IH患者和对照组的血清离子钙均升至相似水平，没有迹象表明IH组因假定的肠道钙吸收过多而出现相对性高钙血症。然而，在禁食期和吸收后期，IH组均明显存在肾小管钙“渗漏”。另一方面，在轻度高钙血症的PHPT患者中，吸收后期相对性高钙血症明显，肾小管钙渗漏也很严重。因此，在评估结石形成患者对口服钙激发试验的反应之前，仔细将隐匿性PHPT与IH患者初步区分开来是至关重要的一步。当做到这一点时，在剩余的IH组中未发现吸收后期相对性高钙血症的证据，高钙尿症似乎起源于“肾脏”而非“吸收”。
