There are multiple definitions:
- finite integration technique(English) 
- Fellow in Training(English) 
- fecal immunochemical test(English) 
- Fracture Intervention Trial(English) - trial of effect of alendronate continuation versus discontinuation in women with low BMD
- BMD, FLEX
- Clinical trials, Injury, Skeleton and bone (formation)
- https://doi.org…359/JBMR.040326