Diagnostic difficulties in polymyalgia rheumatica cases with normal erythrocyte sedimentation rate and C-reactive protein values

Polymyalgia Rheumatica (PMR) is an inflammatory disease which does not have specific diagnostic tests or pathological symptoms and is identified based on clinical characteristics. Among acute phase reactants (APR), the erythrocyte sedimentation rate (ESR) and C-Reactive Protein (CRP) are laboratory findings used in diagnosis and follow-up. In this study, it was aimed to determine the incidence of normal ESH and CRP in patients diagnosed with PMR and identify the distinguishing characteristics of these patients. PMR patients who were clinically diagnosed at a single center were reviewed. After the presence of bursitis was demonstrated with ultrasonography in patients with normal ESR and CRP rates, they were accepted to have PMR. Among all 54 patients (63% female), ESR and CRP values were normal in 8 patients (14%), and serum amyloid A (SAA) was determined to be elevated in all these patients. In the comparisons of the groups with normal and high levels of ESR and CRP, it was found that the group with normal ESR and CRP values had a younger age of diagnosis (P = .027), a longer symptom duration (P < .001), and a lower comorbidity rate (P = .010). PMR patients can have normal ESR and CRP values at the time of their diagnosis. While bursitis can be demonstrated with ultrasonography in patients who are clinically evaluated to have PMR, APRs such as SAA other than ESR and CRP can also be used.