What is relapsed and refractory myeloma? | Experts Explain

[@geomancer6371]

In the graph at 0:30, the y-axis says M-proteins in g/L. I assume these proteins are the free light chain (either kappa or gamma) which determine myeloma? And how come the units in our hospital uses are mg/L, with 19 mg/L being the threshold for Kappa? Is the graph unit wrong or is our hospital's units wrong?