Does the presence of osteoporosis change the extent of workup that should be performed for an older patient with otherwise serologically low-risk MGUS?  

In brief - no, it shouldn't. While some previous studies have suggested that patients with MGUS are more likely to develop osteoporosis than those who don't, this is often related to confounders when MGUS is picked up clinically - in other words, patients with comorbidities that prompt a doctor to l...