CRP and synovitis: Inciarte-Mundo et al. evaluated the relationship between serum calprotectin levels and PDUS synovitis in RA and psoriatic arthritis (PsA) patients who were under tumour necrosis factor-alpha inhibitor treatment.26 They showed a more significant correlation between serum calprotectin and doppler and synovial hypertrophy scores than CRP and ESR.