title: Phosphate and carbonate salts of calcium support robust bone building in osteoporosis.
abstract: BACKGROUND
  Calcium is an essential cotherapy in osteoporosis treatment. The relative effectiveness of various calcium salts for this purpose is uncertain. Many older women with osteoporosis have phosphorus intakes of <70% of the Recommended Dietary Allowance.
  
  
  OBJECTIVE
  Our objective was to test the hypothesis that calcium phosphate would better support anabolic bone building than would calcium carbonate.
  
  
  METHODS
  This study was a 12-mo, randomized, positive-comparator, 2-arm, single-blind clinical trial in 211 patients treated with teriparatide who consumed <1000 mg phosphorus/d. Participants were randomly assigned to receive, in addition to teriparatide and 1000 IU cholecalciferol, 1800 mg calcium/d as either tricalcium phosphate or calcium carbonate. The primary endpoints were changes in lumbar spine and total hip bone mineral densities (BMDs); secondary endpoints were changes in bone resorption biomarkers and serum and urine calcium and phosphorus concentrations.
  
  
  RESULTS
  In the combined group, the lumbar spine BMD increased by 7.2%, and total hip BMD increased by 2.1% (P < 0.01 for both). However, there was no significant difference between calcium-treatment groups, and there were no significant between-group differences in serum calcium and phosphorus concentrations or in urine calcium concentrations. Bone resorption biomarkers increased in both groups, as expected with teriparatide, but the increases in the 2 calcium groups did not differ significantly.
  
  
  CONCLUSIONS
  Tricalcium phosphate and calcium carbonate appear to be approximately equally effective in supporting bone building with a potent anabolic agent; phosphate salt may be preferable in patients with restricted phosphorus intakes. This trial was registered at clinicaltrials.gov as NCT00074711.
authors.affiliation: Osteoporosis Research Center, Creighton University, Omaha, NE, USA. rheaney@creighton.edu
authors.forename: Robert P
authors.initials: RP
authors.lastname: Heaney
authors.forename: Robert R
authors.initials: RR
authors.lastname: Recker
authors.forename: Patrice
authors.initials: P
authors.lastname: Watson
authors.forename: Joan M
authors.initials: JM
authors.lastname: Lappe
mesh_terms: D000284:Administration, Oral; D000368:Aged; D015992:Body Mass Index; D015519:Bone Density / Q000187:drug effects*; D001846:Bone Development / Q000187:drug effects*; D002118:Calcium / Q000097:blood; D002119:Calcium Carbonate / Q000008:administration & dosage / Q000627:therapeutic use*; D002130:Calcium Phosphates / Q000008:administration & dosage / Q000627:therapeutic use*; D002762:Cholecalciferol / Q000008:administration & dosage / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000188:drug therapy*; D018579:Patient Selection; D016037:Single-Blind Method; D013607:Tablets
chemical_list: D002130:Calcium Phosphates; D013607:Tablets; D002762:Cholecalciferol; D002119:Calcium Carbonate; C018392:tricalcium phosphate; D002118:Calcium