To evaluate the adequacy of simple calcium restriction for patients with idiopathic calcium stones the effect of 5 days of calcium restriction without oxalate restriction on renal excretion of calcium and oxalate, and the corresponding probability of stones were assessed in 50 controls and 48 patients. Renal excretion of calcium decreased and that of oxalate increased significantly in all groups but the importance of the changes was critically dependent upon the underlying pathophysiological condition. The probability of stones decreased only in patients with absorptive hypercalciuria type II owing to the usual excessive calcium intake and increased in those with absorptive hypercalciuria type I and renal hypercalciuria, which are associated with true hyperabsorption of calcium and represent the 2 forms of idiopathic hypercalciuria. We believe that simple calcium restriction is beneficial for patients with idiopathic calculi only when the hypercalciuria is caused by exaggerated intake of calcium, since it increases the probability of stones in patients with idiopathic hypercalciuria. Calcium restriction always is associated with an increase in oxalate excretion, suggesting that simultaneous oxalate restriction should be added in all cases to decrease the probability of stones.
The probability of being a stone former (PSF) was calculated in 3 groups of idiopathic calcium stone formers [with normocalciuria (NC), dietary hypercalciuria (DH) and idiopathic hypercalciuria (IH)] in 4 conditions: while (1) on a free diet; (2) on a calcium- and oxalate-restricted diet during 4 days; (3) after an oxalate load, while on a 1.5-gram calcium diet, and (4) after an oxalate load while on a calcium-restricted diet. Combined calcium and oxalate restriction significantly decreased PSF only in NC and DH whereas the decrease was not significant in IH because of a concomitant significant increase in oxalate excretion. Increase of PSF with the oxalate load was significantly greater during a calcium-restricted diet than during the 1.5-gram calcium diet in all groups of patients (4,6 and 12 times greater in NC, DH and IH, respectively). These data show the critical role of oxalate restriction when calcium is restricted in order to decrease the PSF. This combined restriction is however not sufficient in idiopathic hypercalciuric patients to decrease their PSF.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.