Seasonal variation in urinary excretion of calcium, magnesium and phosphate in manic-melancholic patients.

The 24-hr urinary excretion of calcium, magnesium and phosphate was measured in 76 normal control persons, 95 manic-melancholic patients not on lithium treatment and 74 lithium-treated manic-melancholic patients. The mean value of the urinary excretion for each of the four seasons during a 5-year period was calculated. The normal control persons had a higher excretion of calcium during the summer months than during the rest of the year; this seasonal variation was not present in the two groups of manic-melancholic patients. Previously reported changes in electrolyte metabolism during lithium treatment were confirmed, but some of the results varied with the season.