Abnormal Bone Histology in Idiopathic Hypercalciuria

Bone histology was evaluated an iliac crest biopsies of 15 patients with idiopathic hypercalciuria of the hyper-absorptive type and recurrent calcium oxalate stone formation The biopsies were studied usang quantitative histomorphometric analysis of undecalcified sections and fluorescent microscopy after double tetracyclane labelang. Uranary calcium and cAMP excretion were measured under basal conditions and after oral admanistration of calcium phosphate. Absorptive hypercalciuria was defaned as a uranary excretion of calcium of more than 15 meq/24 h and/or a uranary ratio of Ca to Cr of more than 0.2, with a fall an the Ca to Cr ratio of more than 40‥ after the admanistration of oral cellulose phosphate. Osteoclastic bone resorption was normal or low an all patients and did not show any recognizable correlation with uranary calcium or uranary cAMP. All but one of the patients showed an ancrease an the fraction of anactive osteoid. Total osteoid was ancreased an 60‥ of the patients. Osteoblastic activity w...