Spinal bone mineral after 5 weeks of bed rest.
Patients put at bedrest for medical reasons lose 1-2% of spinal bone mineral per week. Losses of this magnitude during even short-term space flights of a few months would pose a serious limitation and require countermeasures. The spinal bone mineral (L2-L4) was determined in 6 healthy males (precision = 2%) before and after 5 weeks of complete bed rest. Only one individual had a significant loss (3%) and the -0.9% mean change for the 6, was not significant (P = 0.06). The average negative calcium balance during the 5 weeks was 4 g or 0.36% of total body calcium, similar to that reported in other bed-rest studies. Spinal bone loss, however, in healthy bed-rested males is significantly less than reported for bed-rested patients, suggesting that a large loss of spinal bone mineral does not occur during space flight missions lasting 5 weeks or less.
D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D001510:Bed Rest; D001842:Bone and Bones / Q000032:analysis*; D002118:Calcium / Q000032:analysis*; D006801:Humans; D007103:Immobilization; D008297:Male; D008903:Minerals / Q000032:analysis*; D013131:Spine / Q000032:analysis*
D008903:Minerals; D000469:Alkaline Phosphatase; D002118:Calcium