[Diurnal variation in plasma oxalate concentration and oxalate clearance in calcium oxalate stone formers with special reference to the effect of oxalate loading].
The diurnal variations in the plasma oxalate concentration and oxalate clearance were examined at the state of oxalate restriction and loading on 6 normal subjects and 11 calcium oxalate stone formers. The oxalate-restricted diet contained 44.5 mg of total oxalate, 32.2 mg of soluble oxalate, and for oxalate loading, spinach (100 g: total oxalate 429 mg, soluble oxalate 156 mg) was added to the oxalate-restricted diet at breakfast. Normal subjects showed a diurnal variation in plasma oxalate at oxalate restriction and loading. The plasma oxalate concentration showed the highest level under the fasting condition, gradually dropped and was then fixed at the lower level during the day. The oxalate clearance during the day was significantly higher (p less than 0.05) than that during the night in normal subjects taking the oxalate restricted diet, and after they were oxalate loaded, it increased significantly (p less than 0.05) for 6 hours, but returned to the level at oxalate restriction during the night. Meanwhile, there was no significant difference in oxalate clearance between day and night in calcium oxalate stone formers. As compared with the control group, there were no significant differences in the diurnal variation in the plasma oxalate concentration, oxalate clearance at oxalate restriction, or in the diurnal variation of the plasma oxalate concentration at oxalate loading. However, the oxalate clearance during the night after oxalate loading increased significantly (p less than 0.05) compared with the control group. Based on the pattern of urinary oxalate excretion during the night compared with the control group, the stone formers were divided into two groups. The first group showed significantly (p less than 0.01) higher oxalate clearance during the night both during oxalate restriction and loading. The oxalate clearance increased significantly up to 8 hours after oxalate loading (p less than 0.01) and during the night (p less than 0.05) compared with the level during oxalate restriction. The plasma oxalate concentration did not increase after loading. The second group showed a significantly (p less than 0.05) lower oxalate clearance during the day after oxalate loading. The oxalate clearance (p less than 0.05) was significantly increased for 4 hours after the loading compared to the during oxalate restriction. The plasma oxalate concentration increased at 6 hours after oxalate loading. There was no significant difference in oxalate clearance during the night. The diurnal variation in plasma oxalate level, a decrease during the day and an increase during the night, was shown in both normal subjects and stone formers.(ABSTRACT TRUNCATED AT 400 WORDS)
Department of Urology, Mie University School of Medicine.
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Kinoshita
D000328:Adult; D002129:Calcium Oxalate / Q000652:urine*; D002940:Circadian Rhythm; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D010070:Oxalates / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D014545:Urinary Calculi / Q000378:metabolism*
D010070:Oxalates; D002129:Calcium Oxalate