Background: in patients with multiple myeloma there is a raised level of a protein, named M-protein. This M-protein is normally used to monitor disease status and evaluate response to treatment, as a decrease in M-protein is taken as evidence of therapeutic efficacy. However, the M-protein has a long half life in serum, approximately three weeks, which tend to be a practical problem, since the investigators can first determine hereafter if the treatment is effective.

A new assay has the possibility only to measure part of this protein, namely "the light chains", which also is measured in a blood sample. The half life of these light chains is much shorter, namely 2-6 hours. In theory, this means a more rapid measure of the effect of a given treatment, thereby being able to determine earlier if the treatment should continue or changed to another strategy.

Purpose: the purpose of this study is to evaluate the clinical value of the use of the serum free light chain (sFLC) assay in comparison to the M-protein in monitoring patients under treatment for multiple myeloma.

Method: the investigators measure sFLC in patients receiving there 1st treatment, either at the time of diagnosis or in the relapse setting. sFLC is measured on a regular basis, and the results are compared to the M-protein.

Inclusion Criteria:

• diagnosis of multiple myeloma
• abnormal serum free light chains
• medical needs of anti-myeloma therapy
• receiving standard anti-myeloma therapy

Exclusion Criteria:

• dialysis
• normal serum free light chains
• dementia

Newly diagnosed patients with multiple myeloma, with medical needs and known patients with multiple myeloma at there 1st relapse and medical needs