Diurnal variations in the urinary excretion of calcium and phosphate in hyperparathyroidism.

The urinary excretion of calcium and phosphate during the day and night was studied in 20 patients with primary hyperparathyroidism and in the same number of controls with normal function of the parathyroids. A significant difference in TRP between day and night was found in the controls but not in the HPT group. In other respects there were no substantial differences between day and night. The higher excretion of calcium observed in the HPT group was largely attributable to the patients with remal calculi. The simplified sampling procedure when only night urine is analysed has no disadvantages-it is more likely to improve the diagnostic reliability as it reduces the influence of meals, for example.