Serum lysozyme in multiple myeloma

SLL's were tested by turbidometric assay on 33 male patients with multiple myeloma with three to 58 tests (mean 11) for each patient over a 7-year period. The age of the patients ranged from 31 to 83 years, with a median age of 58 years. SLL's in the normal controls were 14.4 +/- 3.5 microgram/ml. Patients with myeloma had a median lysozyme level of 16 microgram/ml and mean of 16.5. The SLL's in patients with lgG1,2,3,4, Iga, and kappa and lambda light-chain myeloma were similar. Slightly higher mean SLL'S were noted in older patients. Patients with severe renal disease also had higher SLL'S. No significant changes in SLL's were seen during infections or during mild granulocytopenia (granulocyte count greater than 500 cells/mm3). In severe granulocytopenia (granulocyte count less than 500 cells/mm3) the SLL's decreased and returned to normal levels when the white blood cell counts improved. In eight patients surviving for more than 5 years, the SLL's were not different from those of the other patients. SLL values in patients with multiple myeloma did not differ significantly by statistical test from those of controls when those patients with impaired renal function are excluded.