High Dose Interval Vitamin D Supplementation in Patients With Inflammatory Bowel Disease Receiving Biologic Therapy

Who May Qualify: - Existing diagnosis of IBD, including Crohn disease, ulcerative colitis, and indeterminate colitis - Receiving treatment with Infliximab or Vedolizumab every 4-8 weeks - Age 5-25 years old, at study entry - Measured serum level of 25-OHD of less than 40 ng/mL in the last 4-8 weeks and no changes in vitamin D supplementation in the interim. Of note, 25-OHD levels are evaluated routinely as part of standard clinical care for IBD Who Should NOT Join This Trial: - History of any underlying kidney disease - History of preexisting liver disease - History of granulomatous disease - Inability to take oral vitamin D3 as a pill - History of hypercalcemia or hypercalciuria - Currently, or within the past 3 months, taking an anti-epileptic medication or Lasix Always talk to your doctor about whether this trial is right for you.