Hyperoxaluria in Patients with Recurrent Calcium Oxalate Calculi: Dietary and Other Risk Factors

Abstract

The presence of mild hyperoxaluria in recurrent calcium oxalate stone formers is controversial. The aim of this study was to identify recurrent stone formers with mild hyperoxaluria and to classify them further by assessing their response to a low oxalate diet. In addition, the prevalence of other risk factors for stone formation in this group of patients was investigated. A total of 207 consecutive patients with recurrent renal calculi were screened and 40 (19%) were found to have mild hyperoxaluria. Of these, 18 (45%) responded to dietary oxalate restriction by normalising their urinary oxalate. The remaining 22 patients were classified as having idiopathic hyperoxaluria and were subdivided into those in whom urinary oxalate excretion was consistently elevated in all specimens measured and those in whom the elevation was intermittent in nature. Dietary oxalate restriction had a partially beneficial effect in lowering oxalate excretion in the patients with persistent hyperoxaluria. No difference in urinary oxalate excretion was found after dietary restriction in the patients with intermittent hyperoxaluria. Other risk factors, including dietary, absorptive and renal hypercalciuria and hypocitraturia, were documented, the prevalence of which (65%) was not significantly different from that (62.5%) found in 40 age- and sex-matched calcium stone formers without hyperoxaluria. The prevalence of hyperuricosuria was significantly greater in patients with hyperoxaluria when compared with stone controls. Further studies are required to elucidate the underlying mechanisms of hyperoxaluria in recurrent stone formers.

Evidence for net renal tubule oxalate secretion in patients with calcium kidney stones

“…Despite similarly low daily dietary oxalate intake in the GCRC, patients, most of whom were stone formers, excreted significantly more oxalate throughout the day. This is not surprising, as previous investigators have noted a 20 -50% prevalence of at least mild hyperoxaluria in the general stoneforming population (2,5,23). Unlike previous studies, however, our data demonstrate a critical role of secretion in accounting for the increased excretion in this population, as approximately one-third of patients were found to be secreting oxalate, with a strong correlation between the highest oxalate excretions and renal tubule secretion.…”

Ethylene Glycol Induced Hyperoxaluria Increases Plasma and Renal Tissue Asymmetrical Dimethylarginine in Rats: A New Pathogenetic Link in Hyperoxaluria Induced Disorders

“…26 Since even mild hyperoxaluria that can easily be controlled with dietary restrictions may cause recurrent calcium oxalate stones, obese individuals, of whom most have moderate hyperoxaluria, are more prone to the effects on the renal vascular epithelium and the tubular epithelium. 27,28 At this point it is not wrong to say that calcium oxalate renal stone disease is part of a systemic disease.…”

Recent advances in the pathophysiology of nephrolithiasis

“…The estimated intake of oxalate ranges between 50 and 1000 mg/day 77,78,89. Oxalate-rich foods primarily include seeds, such as chocolate that is derived from tropical cacao tree, and leafy vegetation, including spinach, rhubarb, and tea.…”