 2. If the participant is treated with active vitamin D in conjunction with calcium supplements, the participant must be taking 0.25 mcgday of calcitriol or 0.5 mcg of alfacalcidol with 1000 milligram mgday of calcium supplement. If the participant is treated with 0.25 mcgday of calcitriol or 0.5 mcg of alfacalcidol or 1000 mgday of calcium supplement, the participant must have a history of inability to be successfully managed on higher doses of at least one of these supplements. 