title: Vitamin B6 metabolites in idiopathic calcium stone formers: no evidence for a link to hyperoxaluria.
abstract: Vitamin B6 metabolites and their potential correlates to urinary oxalate excretion in idiopathic calcium stone formers (ICSF) compared with healthy subjects were investigated. This clinical study was performed in a population of male ICSF with (Hyperoxalurics, n=55) or without hyperoxaluria (Normooxalurics, n=57) as well as in 100 healthy male control subjects. Pyridoxal 5'-phosphate serum concentration (S-pyridoxal 5'P) and 24-h urinary excretion of 4-pyridoxic acid (U-4pyridoxic acid) were measured using HPLC; 24-h urinary excretion of oxalate (U-oxalate) was measured concurrently. A subgroup of subjects (40 Hyperoxalurics, 15 Normooxalurics and 50 controls) underwent the same measurements before and after 7-day pyridoxine loading per os (pyridoxine hydrochloride, 300 mg/d). Under usual conditions, U-4pyridoxic acid was similar in the three groups, whereas mean S-pyridoxal 5'P was significantly lower ( p<0.0001) in the Hyperoxalurics (59.6+/-21.2 nmol/L) and in the Normooxalurics (64.9+/-19.7 nmol/L) than in the controls (86.0+/-31.0 nmol/L). No correlation could be found between U-oxalate and U-4pyridoxic acid or S-pyridoxal 5'P. After B6 loading, S-pyridoxal 5'P was still significantly lower in the Hyperoxalurics (415+/-180 nmol/L, p<0.001) and in the Normooxalurics (429+/-115 nmol/L, p=0.036) than in the controls (546+/-180 nmol/L), although there was no difference between groups for U-4pyridoxic acid. No correlation in any group could be found between changes in U-oxalate and changes in U-4pyridoxic acid or S-pyridoxal 5'P. Although there is no vitamin B6 deficiency in ICSF with or without hyperoxaluria, these patients, on average, have lower levels of S-pyridoxal 5'P than healthy subjects. However, this slight decrease does not seem to account for idiopathic hyperoxaluria.
authors: Department of Nephrology, University Hospital, P.O. Box 69, 06002, Nice cedex 1, France.
authors: Agnes
authors: A
authors: Kaelin
authors: Jean-Paul
authors: JP
authors: Casez
authors: Philippe
authors: P
authors: Jaeger
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid; D003430:Cross-Sectional Studies; D006801:Humans; D006959:Hyperoxaluria / Q000097:blood / Q000150:complications* / Q000652:urine; D007669:Kidney Calculi / Q000097:blood / Q000150:complications* / Q000378:metabolism* / Q000652:urine; D008297:Male; D008875:Middle Aged; D010070:Oxalates / Q000652:urine; D011732:Pyridoxal Phosphate / Q000097:blood; D011735:Pyridoxic Acid / Q000652:urine; D011736:Pyridoxine / Q000494:pharmacology; D025101:Vitamin B 6 / Q000378:metabolism*
chemical_list: D010070:Oxalates; D011735:Pyridoxic Acid; D011732:Pyridoxal Phosphate; D025101:Vitamin B 6; D011736:Pyridoxine