La determinazione delle catene leggere libere nel siero può sostituire la ricerca e quantificazione della proteinuria di Bence Jones nella pratica clinica?

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ABSTRACT

Can serum free light chain determination replace detection and quantitation of Bence Jones proteinuria in clinical practice?

Serum free light chain (FLC) determination became available for clinical laboratories 12 years ago. Since its introduction, it has been postulated that the urine study (i.e. Bence Jones proteinuria detection and quantitation) could have been abandoned due to the higher sensitivity and better practicability of the serum FLC assay. This paper investigates this hypothesis, presenting the evidence derived from the literature so far. Primary studies show some results in favour of the urine study discontinuation; however, a correct evaluation of this evidence is hampered by the lack of information about the sensitivity of the immunofixation method used as comparison. A number of guidelines and recommendations has been published on plasma cell dyscrasias, examining different clinical settings where the two tests can be used (screening, diagnosis, risk stratification, monitoring and response to treatment). Serum FLC measurements should be preferred in the screening and risk stratification subsets [apart from amyloidosis and POEMS (Polineuropathy, Organomegaly, Endocrinopathy, Monoclonal protein and Skin changes) syndrome]; on the contrary, determination of Bence Jones proteinuria should be used in the assessment of the response to therapy, when disease is quantifiable. At the moment, the FLC determination cannot replace the urine study in any circumstance and the two tests should be considered complementary until other evidences will be provided. Considering the dependence of both tests upon renal function, studies examining this issue could help elucidating their role in the wide scenario of plasma cell dyscrasias.

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