Dingli D et al. (2005) Focal and segmental glomerulosclerosis and plasma cell proliferative disorders. Am J Kidney Dis 46: 278–282

Focal segmental glomerulosclerosis (FSGS) is an increasingly common cause of end-stage renal disease. Although linked with several conditions, many cases of FSGS are of unknown etiology (primary FSGS). Because blood levels of proteins can be disturbed by plasma-cell disorders (a known risk factor for renal disease), Dingli et al. proposed that plasma-cell disorders might also underlie some cases of primary FSGS. They investigated this hypothesis in a retrospective study of data from patients attending the Mayo Clinic Rochester.

The authors cross-referenced patients diagnosed with FSGS within an approximate 10-year period against a database of patients who had monoclonal protein in their urine, blood, or both. Of the 40 patients identified, 27 were excluded from further analysis for reasons including the identification of a secondary cause for FSGS. Nine of the remaining 13 patients had monoclonal gammopathy of undetermined significance (MGUS) and four had multiple myeloma (MM). FSGS was diagnosed within a median 0.3 years of the plasma-cell disorder (range 0.01–7 years). The number of cases of MGUS/MM in the study group significantly exceeded the number expected from a demographically equivalent population (1.5, P <0.001).

Patients with MGUS are generally not treated because they have a low rate of progression to MM. As the four patients with MM showed a clinically objective response to treatment and a reduction in proteinuria, Dingli et al. believe that they have elucidated a temporal and epidemiological link between plasma-cell proliferation and FSGS. They suggest, therefore, that treatment of the underlying condition might resolve both primary FSGS and the associated renal dysfunction.