An increased CDT camouflaged a monoclonal light chain gammopathy: An approach for diagnosis

Carbohydrate-deficient transferrin (CDT) is the most reliable indicator for the detection of chronic alcohol consumption. Recently, we have investigated a clinical case in which a concomitant monoclonal light chain gammopathy mimicked an increase of this biomarker. A patient's serum was routinely examined by capillary electrophoresis (CE) for evaluation of CDT, and it was subsequently analysed through high-performance liquid chromatography (HPLC) to confirm the referred result. Then, according to the patient's clinical history, we performed serum and urine immunofixation, together with k and λ free light chain measurement. The pathological CDT value obtained by CE agreed with the patient's previous data, but it was not confirmed by the HPLC. The patient's medical record revealed hypogammaglobulinaemia since 2006, which had been recently examined by a haematological visit. Serum and urine immunofixation revealed a light chain gammopathy, which had been suspected but never confirmed by laboratory assessment. The k and λ free light chain measurement completed the diagnostic process. To the best of the authors' knowledge, this is the first study of its kind to report on a perfect camouflaging of a monoclonal light chain as disialo-transferrin. The importance of the careful examination of the patient's clinical history for the correct evaluation of laboratory results, thereby preventing misinterpretations, is also highlighted. •CDT testing is the examination that is requested routinely for alcohol assumption in forensic evaluation•EtG in hair is taking relevance in forensic examination due to its more accurate determination and longer half-file•Laboratory results that highlight concomitant pathologies not yet diagnosed should be timely and correctly evaluated