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- Title
Sensitivity to meat protein intake and hyperoxaluria in idiopathic calcium stone formers.
- Authors
Nguyen, Quan-Vinh; Kälin, Agnes; Drouve, Uschi; Casez, Jean-Paul; Jaeger, Philippe; Nguyen, Q V; Kälin, A; Drouve, U; Casez, J P; Jaeger, P
- Abstract
Sensitivity to meat protein intake and hyperoxaluria in idiopathic calcium stone formers. Background. High protein intake is an accepted risk factor for renal stone disease. Whether meat protein intake affects oxaluria, however, remains controversial in healthy subjects and in stone formers. This study was designed (1 ) to test the oxaluric response to a meat protein load in male recurrent idiopathic calcium stone formers (ICSFs) with and without mild metabolic hyperoxaluria (MMH and non-MMH, respectively), as well as in healthy controls, and (2 ) to seek for possible disturbed vitamin B6 metabolism in MMH, in analogy with primary hyperoxaluria. Methods. Twelve MMH, 8 non-MMH, and 13 healthy males were studied after five days on a high meat protein diet (HPD; 700 g meat/fish daily) following a run-in phase of five days on a moderate protein diet (MPD; 160 g meat/fish daily). In both diets, oxalate-rich nutrients were avoided, as well as sweeteners and vitamin C-containing medicines. Twenty-four–hour urinary excretion of oxalate was measured on the last day of each period, along with 4-pyridoxic acid (U4PA ) and markers of protein intake, that is, urea, phosphate, uric acid, and sulfate. Serum pyridoxal 5′ phosphate (SP5P ) was measured after protein loading. Results. Switching from MPD (0.97 ± 0.18 g protein/kg/day) to HPD (2.26 ± 0.38 g protein/kg/day) led to the expected rise in the urinary excretion rates of all markers of protein intake in all subjects. Concurrently, the mean urinary excretion of oxalate increased in ICSFs taken as a whole (+73 ± 134 μmol/24 h, P = 0.024) as well as in the MMH subgroup (+100 ± 144 μmol/24 h, P = 0.034) but not in controls (-17 ± 63 μmol/24 h). In seven ICSFs (4 MMH and 3 non-MMH) but in none of the healthy controls (P = 0.016, chi square), an increment in oxaluria was observed and considered as significant based on the intra-assay coefficient of variation at our laboratory (8.5%). There was no difference in SP5P and U4PA between the groups after protein loading. Conclusion. Approximately one third of ICSFs with or without so-called MMH are sensitive to meat protein in terms of oxalate excretion, as opposed to healthy subjects. Mechanisms underlying this sensitivity to meat protein remain to be elucidated and do not seem to involve vitamin B6 deficiency.
- Subjects
OXALURIA; PROTEINS; CALCIUM; KIDNEY stones; VITAMIN B6 metabolism; CLINICAL trials; COMPARATIVE studies; DIET in disease; DIET therapy; RESEARCH methodology; MEAT; MEDICAL cooperation; METABOLIC disorders; OXALIC acid; DIETARY proteins; PYRIDINE; RESEARCH; SULFATES; VITAMIN B complex; HYDROXY acids; EVALUATION research
- Publication
Kidney International, 2001, Vol 59, Issue 6, p2273
- ISSN
0085-2538
- Publication type
journal article
- DOI
10.1046/j.1523-1755.2001.00744.x