The remodeling transient and the calcium economy.
The remodeling transient describes a change in bone mass that lasts one remodeling cycle following an intervention that disturbs the calcium economy. We demonstrated the transient in a study of the response of bone density to calcium/vitamin D3 supplementation and show the hazards of misinterpretation if the transient is not considered.


BACKGROUND
The remodeling transient describes a change in bone mass that lasts for one remodeling cycle following an intervention that disturbs the calcium economy.


METHODS
We report an intervention with calcium and vitamin D supplementation in 208 postmenopausal African-American women where the remodeling transient was considered a priori in the study design. Both groups (calcium alone vs. calcium + 20 microg (800 IU) vitamin D3) were ensured a calcium intake in excess of 1200 mg/day.


RESULTS
There were no differences between the two groups in changes in BMD over time. These BMD changes were therefore interpreted to reflect increased calcium intake in both groups but not any influence of vitamin D. A transient increase in bone mineral density was observed during the first year of study, followed by a decline. The remodeling period was estimated at about 9 months, which is similar to histomorphometric estimates.


CONCLUSIONS
It is problematic to draw conclusions concerning interventions that influence the calcium economy without considering the remodeling transient in study design. Studies of agents that effect bone remodeling must be carried out for at least two remodeling cycles and appropriate techniques must be used in data analysis.
Aloia
J F
JF
Bone Mineral Research Center, Winthrop University Hospital, Mineola, NY, USA. jaloia@winthrop.org
Arunabh-Talwar
S
S
Pollack
S
S
Yeh
J K
JK
D015502:Absorptiometry, Photon; D001741:Black or African American; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000187:drug effects* / Q000502:physiology; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D016723:Bone Remodeling / Q000502:physiology*; D002118:Calcium / Q000097:blood / Q000494:pharmacology*; D002762:Cholecalciferol / Q000097:blood / Q000494:pharmacology*; D024042:Collagen Type I / Q000097:blood; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D006801:Humans; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging / Q000188:drug therapy*; D010281:Parathyroid Hormone / Q000097:blood; D010455:Peptides / Q000097:blood; D011884:Radius / Q000000981:diagnostic imaging
D015415:Biomarkers; D050071:Bone Density Conservation Agents; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D002762:Cholecalciferol; D002118:Calcium