RESUMEN
BACKGROUND: In humans, it has been suggested that low-level mean platelet volume (MPV) may be related to secondary thrombosis due to inflammation. For this reason, MPV can be used as a marker showing inflammation in the body. OBJECTIVES: To evaluate the association of MPV with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Disease Activity Score-28 (DAS-28), and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in patients with rheumatic diseases. METHODS: The study consisted of 261 patients with rheumatoid arthritis (203 females, 77.8%; 58 males, 22.2%), 85 patients with ankylosing spondylitis (57 males, 67.1%; 28 females, 32.9%), 56 patients with familial Mediterranean fever (32 females, 57.1%; 24 males, 42.9%) and 194 patients (139 females, 71.6%; 55 males, 28.4%) with other rheumatic diseases (Behçet's disease, psoriatic arthritis, spondyloarthropathy, systemic lupus erythematosus, systemic sclerosis, or undifferentiated connective tissue disease). RESULTS: There was an inversely significant correlation between MPV and ESR and CRP in patients with rheumatoid arthritis (r = -0.164, p = 0.008). Mean platelet volume was negatively correlated with DAS-28-ESR/CRP (r = -0.393, p < 0.001) in rheumatoid arthritis. Mean platelet volume was inversely correlated with BASDAI (r = -0.580, p < 0.001) in ankylosing spondylitis. In the group with familial Mediterranean fever (especially M694V homozygous), there was a negative correlation between MPV and ESR and CRP (p < 0.001). Mean platelet volume and CRP were negatively correlated in psoriatic arthritis (r = -0.599, p = 0.011). Mean platelet volume and ESR were inversely related in patients with systemic lupus erythematosus (r = -0.421, p = 0.045). There was a negative correlation between MPV and ESR (r = -0.219, p = 0.002), and between MPV and CRP (r = -0.208, p = 0.004) in other rheumatic diseases. CONCLUSIONS: The lower MPV level surrogates active and/or chronic inflammatory state in the body. Thus, MPV may be used as a negative acute-phase reactant in rheumatic diseases.