A rare type of multiple myeloma in which the plasma cells synthesize but do not secrete immunoglobulins. As a result, none of the immunoglobulins appear out of the normal range. The symptoms are generally the same with those of immunoglobulin-secreting myeloma; however, the incidence of renal insufficiency is lower in non-secretory myeloma. The diagnosis can be missed because of the absence of monoclonal immunoglobulin in the serum or urine.