Effects of Calcium Infusion on Urinary Hydroxyproline and Phosphorus: Evaluation as a Diagnostic Test

The effects of calcium infusion (15 rag Ca/kg body wt) on urinary hydroxyproline and phosphorus have been studied in 4 patients with hyperparathyroidism, 3 patients with hypoparathyroidism, 7 normal subjects, 13 stone formers, 4 patients with chronic renal insufficiency, 2 patients with acromegaly, 1 patient with sarcoidosis, 1 with hyperthyroidism, 1 with Paget's disease, 1 with milk-alkali syndrome and 1 with pseudohypoparathyroidism. Calcium infusion lowered urinary hydroxyproline and phosphorus 14% or more below control levels in all subjects except those with hyperparathyroidism, hypoparathyroidism or pseudohypoparathyroidism. The decreases in urinary hydroxyproline and phosphorus occurred on the day of infusion in all subjects except 2 with chronic renal insufficiency, in whom they occurred on the day after infusion. The results indicate that the test may be of value in evaluating parathyroid function.