@sassysaveur, i think any of the doctors can order a DXA scan for monitoring, but for Glucocorticoid-Induced Osteoporosis (GIOP), the "who" matters. Since your rheumatologist prescribed prednisone and will manage the taper, they seem to be in the best position to coordinate this, and i believe there are guidelines for bone protection. However, if your endocrinologist has a specific sub-specialty in metabolic bone disease, they may be better suited to manage the actual pharmacotherapy. In any case, make sure at least one of them is actively tracking your bone status so nothing falls through the cracks. Whichever doctor you choose, you can always use the other for a second opinion, as drug therapy for osteoporosis can get complicated quickly.