Fasting and Post-Calcium Load Serum Calcium, Parathyroid Hormone, Calcitonin, in Male Idiopathic Calcium Urolithiasis - Evidence for a Basic Disturbance in Calcium Metabolism

In male healthy controls (n = 12), male renal calcium stone patients with either normocalciuria (NC; n = 12) or idiopathic hypercalciuria (I-HC; n = 12), all ideally matched for age and body weight, the response of variables of mineral metabolism to a calcium-rich oral test meal was evaluated. In all groups the postprandial urinary cyclic AMP is decreased as compared with fasting urine, indicating that the parathyroid glands are suppressible by oral calcium. However, in I-HC serum total calcium was significantly higher than in controls both basally and in the postprandial period; the associated mid-regional (bioinactive) serum parathyroid hormone was also elevated, but serum parathyroid hormone recognizing the amino terminal (bioactive) region of the molecule was significantly decreased. Also in I-HC, serum alkaline phosphatase is elevated, whereas urinary hydroxyproline in both fasting and postprandial urine is unchanged. The NC group holds an intermediate position between I-HC and controls. It can be concluded that I-HC subjects may suffer from a more basic disturbance of calcium metabolism which may help explain the nature of their hypercalciuria.