Occurrence of monoclonal components in general practice: clinical implications.

We report on the occurrence of monoclonal components observed in a provincial hospital in northern Italy from 1987 to 1990. The monoclonal components were detected by visual inspection of high-resolution acetate serum electrophoreses and typed by immunofixation. The percentage of monoclonal components increases steeply with age, and reaches a plateau of 7-8% in individuals over 55 years old. Besides the high percentage of monoclonal component, the other relevant finding of this study is that approximately 80% of monoclonal components are of low concentration (less than 5 g/l). Most of these subjects with small monoclonal component passed undetected in the previous studies on the prognostic significance of monoclonal gammapathy. These findings indicate the need for a revision of the current concepts on the biological and clinical significance of MC discovered by chance.