blood calcium and colonoscopy.....

Hi, I am 2 years out of surgery and saw my regular doctor.  He ordered a colonoscopy, I am 57, and a blood level for calcium when I asked about my bone density.  He is somewhat familiar with gastric bypass and will do what he can, however, i remember some cautions given on the board about drinking a lot of  fluids--I will be taking the "half-litely", less water....and also remembered something about blood calcium not being a good indicator of over all calcium....can anyone refresh or enlighten me? Thanks! Betty

Blood calcium tells you how much calcium is floating around in your body right now.  The main storage of calcium is in the bone (not the blood).  Calcium is carried through the body by proteins - many factors can affect these numbers including poor protein status and altered fluid balance (that is dehydration or over-hydration).  If you want to know about bone density, the best test is a DEXA scan.  This test can also evaluate your calcium by measuring if you are losing calcium in areas of the bone prone to losses.  A serum (blood) calcium is not a good indicator of total body stores/status. Good luck with your scope!

thank you so much, I will speak to my doctor about that! Betty