CRP and systemic lupus erythematosus: During the last 12 years, based on a variety of articular and systemic manifestations, persistently elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), antinuclear antibody (ANA) positivity and, on some occasions, low-titer RF positivity, he had received different diagnoses including RA, SLE and undifferentiated connective tissue disease (UCTD).