The anion gap in asymptomatic plasma cell dyscrasias.

The presence of a low anion gap in patients with multiple myeloma has recently been emphasized. This has been related to the retention of chloride and bicarbonate anions to offset the cationic charge of the monoclonal immunoglobulins. We now report the presence of a low anion gap in 50 patients with asymptomatic plasma cell dyscrasias. No correlation was found between the size of the anion gap and the height of the paraprotein "spike" or the size of the anion gap and an index of the net cationic charge of the monoclonal immunoglobulins.