If you are taking Calcium, you should also be taking Vitamin D, too.
I take about 1500 mgs of Calcium and about 2600 IUs of Vitamin D (counting what's in my multivitamin). The D has been shown to help absorb calcium better. Since Vitamin D is absorbed in the lower GI (colon) people with UC have a higher chance of being vitamin D deficient.
Please have your GI or GP check your vitamin D levels. If you are low, you'll need a prescription strength supplement even, maybe.
Suebear is right, you could be taking Fosamax or a number of other osteoporosis meds, but Celebrex is not for osteoporosis, but arthritis instead.
To put it in perspective I am 34 and my Z-score is -1.8. The Z-score matches you with other people of the same age, gender, ethnicity, and something else that I forget. A Z-score of less than minus-1.5 generally means that factors other than aging are contributing to osteoporosis (UC???). I am trying to get it higher with the Calcium, Vitamin D (and exercise). Will have another DEXA scan in December to see how it looks.
I eat plenty of dairy, etc. Had only been on pred once at the time of my first DEXA scan. My grandmother had osteoporosis pretty bad, and she maybe had UC, too, so that is probably my predisposition.
Age 34, Diagnosed with UC September 2008
Started Azathioprine 100 mgs 6/22/2009 and Apriso 4 tabs daily 6/11/2009
Biotin 5 mg
Vitamin D 2,000 IU per day
Calcium 1500 mg per day
Flaxseed Oil 2000 mg per day
Also tried: Remicade, Asacol, Rowasa, Cantasa, Prednisone 2 times for about 3 months each