The incidence and significance of pseudoparaproteins in a community hospital.

Pseudoparaproteins were observed in 129 (10.5%) of 1,229 high resolution protein electrophoretic fractionations of serum (N = 847), urine (N = 368), or cerebrospinal fluid (N = 14) performed in this laboratory during a 12-month period. The pseudoparaproteins identified in serum electrophoretic patterns included fibrinogen, C-reactive protein, hemoglobin-haptoglobin complex, elevated beta-globulins (transferrin and C3), lysozyme (muramidase), and an extended migration artifact. In the electrophoretic patterns of urine, the pseudoparaproteins consisted of nonspecific gamma zone bands of varying intensity. Gamma zone trace protein in the cerebrospinal fluid was often of sufficient intensity to cause potential confusion with oligoclonal bands. Awareness of the characteristic electrophoretic migration positions of these pseudoparaproteins helps to avoid unnecessary ancillary testing and expense.