Seasonal variation in urinary excretion of calcium, oxalate, magnesium and phosphate on free and standard mineral diet in men with urolithiasis.

Seasonal variations of urine volume and urinary excretion of calcium, oxalate, magnesium and phosphate were studied in 118 men with urolithiasis on a standard mineral diet and on free diet. The 24-hour urine volume did not vary by season. There was no significant seasonal variation in the excretion of urinary calcium, oxalate, magnesium or phosphate on a standard mineral diet. While on a free diet the patients' urinary excretion of calcium showed statistically significant seasonal differences between age groups. The seasonal variations in the excretion of urinary oxalate and phosphate were statistically significant on free diet, but did not differ by age. The urinary excretion of magnesium was not affected by season nor age. Dietary intake probably best explains seasonal changes in the urinary excretion of calcium, oxalate and phosphate.