@barbarian1 That is the purpose of a baseline biopsy, to show the initial health of your bone marrow cells. Normal kappa LC is around 3.3-19.4 mg/L and Lambda 5.7-26.3 mg/L. Normal range of kappa/lambda is 0.65 to 1.65, although if someone has reduced kidney function then the ratio may be higher. Biopsies can also be used to rule out diseases, which allows doctors to look for other causes. I had a biopsies last summer that ruled out amyloidosis, MGRS, and IgA nephropathy which gave me a lot of comfort because those come with a lot of risks. https://bloodcancer.org.uk/understanding-blood-cancer/mgus/what-is-mgus/