[Monoclonal free light-chain immunoglobulins: their clinical interpretation]

23 cases of free light chains (FLC) occurrence in the blood and/or urine in the absence of monoclonal gammopathy are reported. Of them 15 cases were attributed to renal diseases associated with deranged catabolism of low-molecular proteins including FLC. In the rest cases FLC hyperproduction in autoimmune diseases was suspected to cause FLC appearance. No correlation was found between the amounts of FLC, creatinine, beta 2-microglobulin, light chains, kappa/lambda proportions.