I have been fairly faithful with my fosamax and calcium supplements for several years, since I was "cold-turkeyed" off estrogen due to breast cancer. I was dismayed to learn this year that my bone density had dropped to -2.9.
Then I read a suggestion for testing the absorption rate of your calcium supplement. Put your pill in vinegar for 30 minutes and see whether it will dissolve. I put a pill in vinegar, forgot about it, and saw three hours later that it had not dissolved.
I believe that my drop in bone density may be related to poorly absorbed calcium. I have switched to another form that is already liquid and "acidified". It is more expensive, but not nearly so expensive as bone loss!
So, friends, please check your calcium to be sure it is absorbing. I am no expert at this. Maybe another of you knows a better way to check this. If so please share it!