[Pseudohypobicarbonatemia in a patient with a kappa IgA monoclonal gammapathy].

Paraprotein interferences assays are known but rather unusual in clinical chemistry.we here report a paraprotein interference with a bicarbonate assay in a IgA kappa-type myeloma patient. Serum bicarbonate level was assessed by the enzymatic method of a multiparametric chemistry analyzer (Advia 1800, Siemens) as well as a specific electrode assay on a blood gas analyzer (GEM 4000, IL). Paraprotein interference with the enzymatic assay was evidenced by an abnomally low bicarbonate level measured by the enzymatic method in contrast with usual levels obtained by using the gas analyzer and with the clinical status of the patient. Therefore, gammapathy has to be taken into consideration when interpreting biological data.