Intestinal Oxalate and Calcium Absorption in Recurrent Renal Stone Formers and Healthy Subjects

Abstract

The fractional intestinal absorption of oxalate and calcium was investigated by isotope techniques in 20 normal subjects and in 12 idiopathic calcium oxalate stone formers. The greatest amount of 14C-oxalate was excreted during the first six hour period in controls as well as in stone formers. The stone formers had a greater intestinal uptake of oxalate (11 +/- 5.1%) than the controls (6.2 +/- 3.7%; p less than 0.01). There was no significant relationship between the fractional absorption of oxalate and the total urinary oxalate excretion. The stone formers also had a higher fractional uptake of calcium compared to the controls (55 +/- 11% vs. 47 +/- 9.1%; p less than 0.05). There was a positive relationship (r = 0.47) between the urinary excretions of calcium and oxalate in the stone formers. During these conditions no correlation could be demonstrated between the fractional absorptions of oxalate and calcium, neither in the stone formers nor in the controls. In conclusion, patients with recurrent formation of calcium oxalate containing stones appear to have an enhanced intestinal uptake of both oxalate and calcium. This disturbance could be of primary pathogenic importance for their stone forming propensity.

Use of a probioitic to decrease enteric hyperoxaluria

“…Factors known to influence the percentage of this dietary oxalate that is absorbed include the availability of free calcium and magnesium ions that can complex with oxalate and decrease its rate of absorption, and the presence of free fats in the distal colon, which can form soaps with calcium and thereby increase concentration of free oxalate [20]. Recent [21,22] and older [23][24][25] studies also support the hypothesis that increased gastrointestinal absorption of oxalate due to factors independent of diet could mediate hyperoxaluria in a subgroup of calcium oxalate stone formers. There is evidence that specific energy-dependent transporters might mediate both net oxalate absorption, as well as oxalate excretion [26].…”

No Contribution of Ascorbic Acid to Renal Calcium Oxalate Stones

“…The daily oxalate intake from a normal diet ranges between 80 and 100 mg (890 and 1,100 pmol/day). How ever, because most of the oxalate seems to be bound by calcium in the small intestine, which is then excreted as insoluble calcium oxalate complex, absorption usually does not exceed 10-20% of the amount present in food [15], Other investigators [16,17] have deter mined values of 8.3 or 6.2 ± 3.7% in normals and 14.6 or 11 ± 5.1% in stone formers. However, Heckers et al [18] believe that the contribution of dietary oxalate is generally underestimated: they indicated that with high intakes of oxalate-rich food, such as choco late, the urinary oxalate values can be in creased by up to 50%.…”

Apocynin-Treatment Reverses Hyperoxaluria Induced Changes in NADPH Oxidase System Expression in Rat Kidneys: A Transcriptional Study

“…More commonly, however, higher concentrations of Ox in human fluids can cause a variety of pathological disorders, including hyperoxaluria, cardiomyopathy, cardiac conductance disorders, renal failure and, in particular, calcium oxalate (CaOx) nephrolithiasis [1]–[3]. Although oxalate can be absorbed by all segments of the intestinal tract, the large intestine appears to be where greatly enhanced oxalate absorption occurs in patients with enteric hyperoxaluria due to ileal disease [4], [5], chronic inflammatory bowel disease [6], as well as fat malabsorption, steatorrhea and sprue [5]. Enteric hyperoxaluria is also a well-documented entity observed in gastrointestinal diseases, such as colitis or Crohn's disease or following ileal resection in jejuno-ileal bypass surgery, and now certain bariatric surgeries for obesity [6]–[10].…”