Defining hypercalciuria in nephrolithiasis

The classic definition of hypercalciuria, an upper normal limit of 200mg/day, is based on a constant diet restricted in calcium, sodium, and animal protein; however, random diet data challenge this. Here our retrospective study determined the validity of the classic definition of hypercalciuria by c...

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Published in:Kidney international Vol. 80; no. 7; pp. 777 - 782
Main Authors: Pak, Charles Y.C., Sakhaee, Khashayar, Moe, Orson W., Poindexter, John, Adams-Huet, Beverley, with Colleagues
Format: Journal Article
Language:English
Published: Basingstoke Elsevier Inc 01-10-2011
Nature Publishing Group
Elsevier Limited
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Summary:The classic definition of hypercalciuria, an upper normal limit of 200mg/day, is based on a constant diet restricted in calcium, sodium, and animal protein; however, random diet data challenge this. Here our retrospective study determined the validity of the classic definition of hypercalciuria by comparing data from 39 publications analyzing urinary calcium excretion on a constant restricted diet and testing whether hypercalciuria could be defined when extraneous dietary influences were controlled. These papers encompassed 300 non-stone-forming patients, 208 patients with absorptive hypercalciuria type I (presumed due to high intestinal calcium absorption), and 234 stone formers without absorptive hypercalciuria; all evaluated on a constant restricted diet. In non-stone formers, the mean urinary calcium was well below 200mg/day, and the mean for all patients was 127±46mg/day with an upper limit of 219mg/day. In absorptive hypercalciuria type I, the mean urinary calcium significantly exceeded 200mg/day in all studies with a combined mean of 259±55mg/day. Receiver operating characteristic curve analysis showed the optimal cutoff point for urinary calcium excretion was 172mg/day on a restricted diet, a value that approximates the traditional limit of 200mg/day. Thus, on a restricted diet, a clear demarcation was seen between urinary calcium excretion of kidney stone formers with absorptive hypercalciuria type I and normal individuals. When dietary variables are controlled, the classic definition of hypercalciuria of nephrolithiasis appears valid.
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ISSN:0085-2538
1523-1755
DOI:10.1038/ki.2011.227