The bone marrow biopsy is used rarely enough that it reveals whatever the hematologist says it reveals. I prefer the "serum Free Light Chain" (sFLC). I have had several of each, and the sFLC seems to be considerably more consistent, although both can easily be ignored by various specialists. The more meaningful question is whether your urine in the toilet makes a foam. I track mine by how large the bubbles get, and how thick the foam is. Lots of foam often means lots of protein, which means Amyloidosis. Mine is Gelsolin and MGUS. oldkarl