Diurnal Variation in Urinary Oxalate

The diurnal variation in urinary oxalate concentration and output was measured in 10 catheterised males. There was an increase in urinary oxalate concentration and output during the day and evening and an early morning decrease. It is thought that the daytime increase is related to dietary oxalate. These data suggest an elevated urinary oxalate excretion is more likely to occur during the day and a 24-hour urine collection may mask this effect.