Kratak sadr`aj: Kvantitativno odre|ivanje monoklonskih imunoglobulina i njihovih fragmenata koristi se za pra}enje toka i terapijskog odgovora kod plazmaproliferativnih bolesti. Cilj odre|ivanja slobodnih lakih lanaca imunoglobulina u seru mu bolesnika jeste provera zna~aja njihovog koli~nika (k/l indeks) kao prognosti~kog faktora remisije, progresije i pre `ivlja vanja. Koncentracije imunoglobulina i slobodnih lakih lanaca odre|ivane su imunonefelometrijskom metodom na analizatoru SIEMENS DADE Behring II sa reagensima (FREELITE, The Binding Site, UK). U ispitivanje je uklju~en 151 bolesnik tokom perioda od 7 godina, koji su razvrstani u 3 grupe: 1. bolest lakih lanaca ili Bence Jones mijelom (37); 2. biklo nalna gamapatija sa slobodnim lakim lancima (23) i 3. mo no klonska gamapatija neutvr|enog znaaja (91). Referen tnim intervalom za k/l indeks smatraju se vrednosti 0,26-1,65. Prema Internacionalnom progno znom indeksu za multipli mijelom, kao patolo{ki uzet je k/l indeks <0,03 ili >32. Bolesnici iz prve dve grupe sa pato lo{kim k/l inde ksom i kombinacijom nepovoljnih faktora rizika (76,7%) imali su prose~no vreme pre`ivljavanja 22-30 meseci, nasuSummary: Quantitation of monoclonal immuno globulins and their fragments is used for moni to ring the plasmaproliferative disease course and the effect of therapy. The aim of free light chains examination was to evaluate the significance of the FLC ratio as a prognostic factor for remis sion, progression and survival in different disease groups. The concentrations of immunoglobulins and free light chains were measured by an immunonep he lometric method on a »SIEMENS« DADE BN II analyser with reagents (Freelite, The Binding Site, UK). In this examination 151 patients from 3 different disease groups: 1. Light chain disease or Bence Jones myeloma (37), 2. Biclonal gammopathy with FLC (23) and 3. Mono clonal gam mo pathy of undetermined significance (91), were investi gated during a period of 7 years. The reference interval for FLC ratio is 0.26-1.65. According to the Inter national Staging System for multiple myeloma, a serum FLC ratio of <0.03 or >32 was taken as abnormal. The patients with light chain disease and biclonal gammopathy with FLC with an abnormal FLC ratio and a combination of adverse risk factors (76.7%) had median survival times of 22-30 months, versus patients with a normal or slightly varied