Osteoporosis and urolithiasis.

Several studies have indicated that up to 60% of idiopathic calcium stone formers present hypercalciuria. Many authors have described reduced bone mineral density (BMD) in stoneformers with hypercalciuria, but osteopenia has also been found in normocalciuric patients. Moreover, Jaeger's group found that bone mass was reduced in all patients with calcium stone disease, independently of hypercalciuria. Many factors may contribute to the pathogenesis of osteopenia in stone formers. A predominant role has been given to the low-calcium diet that is still prescribed in nephrolithiasis. Also slight metabolic acidosis, which is frequently present in stone formers eating a diet rich in animal protein, can contribute to bone loss. Finally, some authors described a pathogenetic role for cytokines, prostaglandins and vitamin D receptor gene polymorphisms.