Polymyalgia rheumatica with normal values of both erythrocyte sedimentation rate and C-reactive protein concentration at the time of diagnosis: a four-point guidance

摘要

Raised values of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) concentration are typical findings in patients with polymyalgia rheumatica (PMR) at the time of diagnosis. In 1979 Bird et al. proposed an ESR of 40 mm/h or higher as a diagnostic criterion, and in 1981 Jones and Hazleman considered a CRP concentration of more than 6 mg/l as an additional criterion. In a sizable proportion of PMR patients – from 7% to 22% – ESR is not raised at the time of diagnosis. However, in these patients, CRP is usually raised [1]. The normal values of both of these biomarkers at the time of diagnosis were rarely reported. Myklebust and Gran [2] found normal both ESR and CRP in 1.2% of 178 PMR patients, and only one patient amongst 177 had normal ESR and normal CRP in a prospective follow-up study conducted in two Italian secondary referral centres of rheumatology [3]. In our medical records (data unpublished), six amongst 265 PMR patients had normal values of both ESR and CRP at diagnosis. The vast majority of these patients had no constitutional manifestations. The reasons why this can be possible in an auto-inflammatory disease are only speculative. The absence of constitutional manifestations could realise a first-favouring element. PMR with low ESR is considered a more benign form of disease, with lower frequency of constitutional manifestations compared to PMR with high ESR [4]. Innate immunity may trigger fever, general malaise, fatigue, and depressive reaction. In patients with PMR, their absence can be a result of interactions between innate and adaptive immunity within a specific genetic background [5]. Some speculated that PMR might be an incomplete form of giant cell arteritis (GCA), manifested in the regions in the proximity of axillary, subclavian, and/or femoral arteritis. A biopsy-proven GCA can be present without elevation of ESR and CRP [6], and in the literature GCA with normal ESR and CRP at diagnosis is much more frequent than PMR with normal values of inflammatory markers. Accordingly, it might be hypothesised that PMR patients with normal values of both ESR and CRP have an occult GCA. In individuals aged 50 years or older, in the presence of: persistent pain involving shoulders, pelvic girdle, and/or neck plus morning stiffness lasting for more than 1 hour plus absence of other different diseases (with the exception of giant cell arteritis), the diagnosis of PMR is possible. The rapid response...