Prolonged weightlessness.
D001862:Bone Resorption; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000378:metabolism / Q000652:urine; D003720:Densitometry; D006801:Humans; D013026:Space Flight; D013997:Time Factors; D014893:Weightlessness
D002118:Calcium