Patients with a clone of B lymphocytes secreting free immunoglobulin light chains filter these freely into the urine. This may occur in amyloidosis and plasma cell dyscrasias, but is particularly important as a marker for myeloma.
This was all in brief about Bence Jones Proteinuria. Now know about Microalbuminuria here-
Microalbuminuriaand about Sodium depletion here- Sodium Depletion