The incidence and possible relevance of Bence-Jones protein in the sera of patients with multiple myeloma.

We present results showing that the detectable incidence of Bence-Jones protein in the sera of patients with multiple myeloma is equivalent to the highest detectable incidence of Bence-Jones protein in highly concentrated urine when tested by immuno-isoelectric focusing. In a series of 25 multiple myeloma patients, immuno-isoelectric focusing showed the incidence of Bence-Jones proteinemia to be 68% compared with a detectable incidence of Bence-Jones proteinuria of 32-64% by immunoelectrophoresis and immuno-isoelectric focusing depending upon the urine concentration factor. In view of the variability of factors governing urinary Bence-Jones protein levels, such as renal catabolism, reabsorption and losses during concentration, we suggest that monitoring of serum Bence-Jones protein by immuno-isoelectric focusing should be carried out in conjunction with measurements of urinary Bence-Jones protein in multiple myeloma.