[Epidemiology of monoclonal gammopathy in a general hospital and a university internal medicine department].

Purpose: Monoclonal gammopathy are common in the general population. We describe biological features and etiology of monoclonal gammopathy diagnosed during more than a ten year period in the Internal Medicine Department of Rennes University Hospital and in all the medical departments of General Hospital of Blois.

Methods: Patients were identified by immunofixation registry of Biochemistry Laboratories in both hospital (from 1990 in Rennes and from 1980 in Blois).

Results: Internal Medicine Department of Rennes University Hospital: 1051 monoclonal gammapathies were identified: 514 men and 537 women. Median age was 71. Isotypes repartition was: IgG 42.8% (450 cases), IgM 31.9% (335), IgA 8.9% (94) biclonal gammopathy 9.8% (103). Sixty-nine monoclonal light chains (6.6%) were identified. Median concentration of monoclonal protein was 14 g/l (1.8-104.4). All department of General Hospital of Blois: 1282 monoclonal gammapathies were identified: 700 men and 582 women. Median age was 79. Isotypes repartition was: IgG 59.7% (765 cases), IgM 27.5% (329), IgA 11.8% (151). Thirty-four monoclonal light chains (2.7%) were identified. Median concentration of monoclonal protein was 5.6 g/l (0.5-96.6). Most frequent diagnosis were: monoclonal gammopathy of undetermined significance or MGUS (77.6% in Blois and 64.1% in Rennes), multiple myeloma (11.9% and 12.7%), Waldenström's macroglobulinemia (4.4% and 8.7%).

Conclusion: Monoclonal gammopathy are common in clinical practice. MGUS account for more than 60% of monoclonal gammopathy. Given their frequency, diagnostic and follow-up strategies must be costless and simple.