Metabolic profile and impact of diet in patients with primary hyperoxaluria.

PURPOSE: The primary goal of this pilot study was to evaluate metabolic characteristics and to examine the impact of diet in patients with primary hyperoxaluria (PH) under controlled, standardized conditions. METHODS: Four patients with genetically confirmed PH collected 24 h urines on their habitual, self-selected diets and on day 1, 6, 7, 8, and 11 under controlled, standardized conditions. The [13C2]oxalate absorption, calcium, and ammonium chloride loading tests were performed. RESULTS: While none of the patients had abnormal findings from the calcium loading test, incomplete distal renal tubular acidosis (RTA) was diagnosed in each of the four patients. Dietary intervention resulted in a significant decrease in urinary oxalate expressed as molar creatinine ratio (mmol/mol) between 30 and 40% in two of four patients. The evaluation of dietary records revealed a high daily intake of oxalate-rich foods as well as gelatin-containing sweets and meat products, rich sources of hydroxyproline, under the habitual, self-selected diets of the two responders. Intestinal oxalate hyperabsorption of 12.4% in one of the two patients may have additionally contributed to the increased urinary oxalate excretion under the individual diet. CONCLUSIONS: Our pilot data indicate that patients with PH may benefit from a restriction of dietary oxalate and hydroxyproline intake. Further research is needed to define the role of distal RTA in PH and to evaluate the hypothesis of an acquired acidification defect.

Bifidobacterium animalis subsp. lactis decreases urinary oxalate excretion in a mouse model of primary hyperoxaluria.

Hyperoxaluria significantly increases the risk of calcium oxalate kidney stone formation. Since several bacteria have been shown to metabolize oxalate in vitro, including probiotic bifidobacteria, we focused on the efficiency and possible mechanisms by which bifidobacteria can influence oxalate handling in vivo, especially in the intestines, and compared these results with the reported effects of Oxalobacter formigenes. Bifidobacterium animalis subsp. lactis DSM 10140 and B. adolescentis ATCC 15703 were administered to wild-type (WT) mice and to mice deficient in the hepatic enzyme alanine-glyoxylate aminotransferase (Agxt(-/-), a mouse model of Primary Hyperoxaluria) that were fed an oxalate-supplemented diet. The administration of B. animalis subsp. lactis led to a significant decrease in urinary oxalate excretion in WT and Agxt(-/-) mice when compared to treatment with B. adolescentis. Detection of B. animalis subsp. lactis in feces revealed that 3 weeks after oral gavage with the bacteria 64% of WT mice, but only 37% of Agxt(-/-) mice were colonized. Examining intestinal oxalate fluxes showed there were no significant changes to net oxalate secretion in colonized animals and were therefore not associated with the changes in urinary oxalate excretion. These results indicate that colonization with B. animalis subsp. lactis decreased urinary oxalate excretion by degrading dietary oxalate thus limiting its absorption across the intestine but it did not promote enteric oxalate excretion as reported for O. formigenes. Preventive or therapeutic administration of B. animalis subsp. lactis appears to have some potential to beneficially influence dietary hyperoxaluria in mice.

An unusual cause of acute renal failure in systemic sclerosis.

BACKGROUND: Scleroderma renal crisis is one of the most life threatening complications of scleroderma. Enteric hyperoxaluria complicates extensive disease or resection of the small intestine in the presence of an intact colon, and is associated with calcium oxalate nephrolithiasis. This cause of renal failure may be underestimated and should be considered in all patients with malabsorption and renal failure. CASE REPORT: A 78 year old woman with systemic sclerosis affecting the bowel developed acute renal failure caused by oxalate nephropathy. RESULTS: The patient's renal failure improved on an oxalate free diet.

Selection of transplantation procedures and perioperative management in primary hyperoxaluria type 1.

This paper outlines the different options of transplant procedures in patients with primary hyperoxaluria type 1. Isolated kidney, isolated liver and combined liver-kidney grafting are discussed. Combined liver-kidney grafting appears to be the preferred treatment for patients already in end-stage renal failure. The potential value of the two other procedures is outlined. Guidelines for perioperative care are given. These involve fluid regime, pyridoxine supplementation, immunosuppression and administration of crystallization inhibitors such as phosphate and citrate. Special emphasis is put on selection of appropriate dialysis procedures and reasons why haemodialysis and continuous haemodiafiltration are the methods of choice.