 The hypothesis underlying this study is that nasally administered calcitonin will stabilize or improve bone mineral density in young patients with ulcerative colitis or Crohns disease. Patients who participate will receive either calcitonin or placebo and will have their bone mineral density measured at the start, at nine months, and at 18 months of study. Participants will also receive age appropriate doses of vitamin D and calcium supplements. Other serological measures of vitamin D status will be obtained every 3 months during the study. 