Laboratory diagnosis of Bence Jones proteinuria in a patient with plasma cell leukemia.

Kappa Bence Jones proteinuria was found by immunoelectrophoretic techniques in a patient with plasma cell leukemia, who presented with no M-proteins either in serum or urine. However, a significant decrease in normal immunoglobulins was observed. On microscopic examination of kidney sections obtained a autopsy, protein casts were seen in the distal tubules. Bence Jones protein was not detected by the conventional heat test.