Paraproteinemia is a frequent laboratory feature in the course of many organ specific or systemic autoimmune diseases. It can be persistent or transient. Autoimmune diseases are secondary to chronic activation of the immune system by antigenic stimuli on a genetic predisposing background. Various pathogens, drugs, and toxins have been implicated as putative etiological agents. Due to hyperactivity of the immune system, individuals with autoimmune disorders may, in occasional cases, be predisposed to the development of paraproteinemia. In this context, paraproteinemia is more likely linked to the biological activity of the underlying disease rather than to an overt neoplastic disorder. Thus, there is growing interest also in studying the role of free light chains (FLCs) as biomarkers of disease activity with the aim of disclosing their exact biological role and their potential use in clinical routine. Moreover, secondary amyloidosis due to chronic inflammation is a well-known late manifestation of several systemic autoimmune disorders. Targeting the pathogenic mechanisms of the disease or the downstream inflammation is the best approach to avoid this complication.
