title: Determinants of osteopenia in male renal-stone-disease patients with idiopathic hypercalciuria.
abstract: OBJECTIVE
  Bone demineralization is frequent in renal-stone formers with hypercalciuria. Although this pathologic link has been recognized for decades, the underlying mechanisms and risk factors associated with osteopenia/osteoporosis in this population remain partially understood.
  
  
  METHODS
  This study retrospectively analyzed determinants of low bone mineral density (BMD) in 65 idiopathic hypercalciuric male renal-stone formers. Clinical and biologic evaluation included BMD measurement, bone-remodeling markers, analysis of calcium metabolism with oral calcium load test, and dietary inquiry.
  
  
  RESULTS
  Patients with osteopenia (n=23, 35% of the population) presented significantly higher fasting calciuria as compared with normal bone density patients (n=42) (calcium/creatinine ratio was 0.32 versus 0.24 mmol/mmol; P=0.006). Analysis of the whole population revealed a negative association between fasting hypercalciuria and BMD (P = 0.003), independent of confounding variables including body-mass index and tobacco consumption. The fasting calcium/creatinine ratio above 0.25 mmol/mmol was associated with a 3.8-fold increase in the risk of low BMD.
  
  
  CONCLUSIONS
  In our study, fasting hypercalciuria after a 2-day calcium-restricted diet appears as the only biologic factor associated with low BMD, suggesting a bone-calcium efflux. Our results support the view of a parathyroid-independent pathologic process that remains to be identified. Hypercalciuric patients with low BMD do not excrete more calcium in 24-hour urine samples than patients without low BMD.
authors: Service des Explorations Fonctionnelles Multidisciplinaires, Hôpital Tenon, 4 Rue de la Chine, 75020 Paris, France. emmanuel.letavernier@tnn.aphp.fr
authors: Emmanuel
authors: E
authors: Letavernier
authors: Olivier
authors: O
authors: Traxer
authors: Michel
authors: M
authors: Daudon
authors: Mohammed
authors: M
authors: Tligui
authors: Jérôme
authors: J
authors: Hubert-Brierre
authors: Dominique
authors: D
authors: Guerrot
authors: Aline
authors: A
authors: Sebag
authors: Laurent
authors: L
authors: Baud
authors: Jean-Philippe
authors: JP
authors: Haymann
mesh_terms: D000328:Adult; D001851:Bone Diseases, Metabolic / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism; D002113:Calcification, Physiologic; D002118:Calcium / Q000097:blood / Q000652:urine; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics; D006801:Humans; D053565:Hypercalciuria / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism; D007669:Kidney Calculi / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D002136:Calcium, Dietary; D002118:Calcium