Analysis of free serum light chains in patients suffering from multiple myeloma complicated by light-chain amyloidosis.

BACKGROUND AL amyloidosis is an acquired systemic disease in which a pathologic amorphous substance produced as a result of abnormal protein metabolism is deposited in the extracellular space of various tissues. OBJECTIVES The aim of the study was to investigate the relationship between the kappa and lambda serum free light chains (sFLCs) and the development of AL amyloidosis in patients suffering from multiple myeloma (MM). MATERIAL AND METHODS The investigations included 70 MM patients, 40 females and 30 males, aged 28-83 years. In 37 persons, MM was had been diagnosed recently; 33 patients had been undergoing treatment. Amyloidosis was diagnosed in 18 patients (25.7%), including nine females, nine males; six had newly diagnosed disease. Fifteen patients developed kidney failure. The control group consisted of 10 healthy donors. The concentration of sFLC ls were determined using the immunonephelometric method and expressed in mg/L. RESULTS In 18 MM patients with amyloidosis the concentration of κ sFLCs ranged from 0.3 to 4780 (x = 854.5, SD = 1289), and was significantly higher (p = 0.039) than in the group without amyloidosis, where the range was from 0.3 to 426.0 (x = 68.9, SD = 98.1). The highest concentration of κ sFLCs was observed in the group of five patients with amyloidosis and renal failure. The concentration of λ sFLCs in patients with amyloidosis ranged from 0.5 to 41600 (x = 3035.7, SD = 9735) and was higher than in MM patients without amyloidosis, where it ranged from 0.5 to 834.0 (x = 79.3, SD = 193). In amyloidosis patients, the concentration of λ sFLCs was significantly higher (p = 0.05) in cases of renal failure as compared with the patients with normal renal function. CONCLUSIONS The concentration of sFLCs is a strong indicator of amyloidosis development in MM patients.