Mineral Metabolism and Bone Mineral Content in Calcium Nephrolithiasis with and without Hyperparathyroidism
We undertook this study to compare different parameters of mineral metabolism and bone mineral content (BMC) in a population of patients affected by hypercalciuria and recurrent calcium nephrolithiasis (RCN) in the presence or absence of histologically-proven primary hyperparathyroidism (pHPT). We evaluated 20 patients (15 males and 5 females, age 24–68 years) with idiopathic hypercalciuria (381±123 mg Ca/day) and RCN. All but two patients had normal iPTH values (224±113 pg/ml), while the TmPO4/GFR was reduced in eight patients. In 11 patients, 1,25(OH)2D (48±19 pg/ml) was at the high-normal level. Urinary calcium excretion was directly related to urinary phosphate excretion (p<0.005) and iPTH (p<0.01). No correlation was found between hypercalciuria and ionized calcium, serum phosphate, alkaline phosphatase, 1,25(OH)2D, blood pH, FECa, and TmPO4/GFR. The BMC, measured by dual photon absorptiometry of the lumbar spine, was 0.88±0.15 g/cm2, which represents 88% of our control values. We compared these patients with a group of 13 patients affected by pHPT and RCN (10 males and 3 females, age 20–70 years) characterized by iPTH and 1,25(OH)2D values of 613±276 pg/ml and 26±10 pg/ml, respectively, and a slightly higher degree of hypercalciuria (436±146 mg Ca/day). The BMC (0.79±0.18 g/cm2) was 84% of the control value. Urinary calcium excretion was increased in males as compared to females as far as the hypercalciuric group was concerned (414±125 vs. 281±23 mg Ca/day, p<0.05), while no difference was found in the pHPT group (461±150 vs. 429±156 mg Ca/day).