Mean platelet volume in familial Mediterranean fever related AA amyloidosis and comparison with common primary glomerular diseases

Abstract

Compared to healthy controls, mean platelet volume (MPV) is frequently higher in patients with Familial Mediterranean fever (FMF) but lower in AA amyloidosis patients. The reason for the difference in MPV levels in FMF patients with and without AA amyloidosis is unclear. The aim of the study was to determine whether low MPV is unique to AA amyloidosis or MPV is similarly low in all glomerular diseases as a result of proteinuria and/or renal dysfunction. We compared pre-biopsy MPV levels of patients with AA amyloidosis secondary to FMF, to MPV levels of patients with membranous glomerulonephritis, focal segmental glomerulosclerosis (FSGS) and IgA nephropathy that all present with proteinuria and renal dysfunction. 703 patients (411 male, 292 female) were included in the study. Mean age was 42.6  14.3 years. There were 124 patients with AA amyloidosis, 224 patients with IgA nephropathy, 188 patients with membranous glomerulonephritis, and 167 patients wit h FSGS. Patients with AA amyloidosis had lower MPV levels compared to patients without AA amyloidosis (7.9  1.2 fL vs. 8.2  0.9 fL respectively, p = 0.008). Patients with AA amyloidosis had significantly lower MPV compared to patients with each of the othe r diagnoses. Independent predictors of MPV were platelet count (β = –0.321, p < 0.001) and CRP (β = – 0.134, p < 0.03). This study is the largest study of MPV in patients with biopsy proven AA amyloidosis and confirms previous studies reporting low MPV in AA amyloidosis. This study indicates that low MPV in AA amyloidosis cannot be explained with proteinuria and renal dysfunction.