Case Studies
Case 6.8 Benign paraproteinaemia
A 49-year-old woman presented with a 6-month history of vague aches and pains in her chest. On examination, she was overweight but had no abnormal physical signs.
Her haemoglobin was 136g/l with a white-cell count of 6.7 x 109/l and a normal differential. Her ESR was 34mm/h. Tests of thyroid function were normal. However, protein electrophoresis showed a small paraprotein band in the gamma region; this band was an IgG of lambda type. Her serum IgG was raised at 20.1g/l (NR 7.2-19.0g/l), with an IgA of 1.9g/l (NR 0.8-5.0g/l) and an IgM of 3.0g/l (NR 0.5-2.0g/l). Electrophoresis of concentrated urine showed no proteinuria. The paraprotein measured 10g/l by densitometry (Chapter 19). A bone marrow examination showed only 12% plasma cells. Together with the absence of osteolytic lesions, the absence of monoclonal free light chains in the urine and normal serum IgA and IgM levels, these findings supported a diagnosis of benign monoclonal gammopathy, also known as a monoclonal gammopathy of unknown significance (MGUS). This woman has been followed at 6-monthly intervals for 3 years with no change in the paraprotein level, and the urine remains free of monoclonal light chains. She will continue to be seen at yearly intervals.
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