Common blood disorder not linked to as many serious diseases as thought

A symptomless blood disorder, monoclonal gammopathy of undetermined significance, known as MGUS, is not linked to as many serious diseases as previously thought. This finding may save patients from undergoing unnecessary workup and treatment according to a study published in the August 2009 issue of Mayo Clinic Proceedings.

MGUS has long been thought to be a precursor of serious disease, such as multiple myeloma, primary amyloidosis and Waldenström macroglobulinaemia. However, for years physicians have reported possible association of MGUS with many more diseases. As a result, some patients with MGUS who had these disorders were subjected to investigations and sometimes additional treatments as a precaution.

MGUS is a fairly common disorder, affecting roughly 3 percent of the US population. This study was supported in part by grants from the National Institutes of Health and the US Public Health Service.

In this study, researchers looked at the records of 17,398 patients, all of whom were uniformly tested for the presence or absence of MGUS. Among the 17,398 samples tested, 605 cases of MGUS were identified. The researchers then looked at the incidence of over 16,000 different diagnosis codes in those with MGUS and those without. They identified 14 real disease associations, while 61 disease associations with MGUS were determined to be likely coincidental. In addition to multiple myeloma, the associations deemed real include vertebral and hip fractures and osteoporosis.

"In addition to the article, we have made available on the journal website an appendix that has the raw data on all 16,062 hospital diagnosis codes which we think will be valuable to other researchers in the field," says S. Vincent Rajkumar, MD, of Mayo Clinic’s Department of Hematology and senior author on the study.

(Source: Mayo Clinic: Mayo Clinic Proceedings: September 2009)