title: Differential diagnosis of elevated erythrocyte sedimentation rate and C-reactive protein levels: a rheumatology perspective.
abstract: OBJECTIVE
  In the case of high erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels, the diagnosis of the underlying disease can be challenging especially in serologically unrevealing patients who have nonspecific clinical findings. We aimed to investigate the final distribution of definitive diagnoses in patients who initially presented with nonspecific clinical findings and sustained elevations in serum ESR/CRP levels.
  
  
  METHODS
  The medical records of patients hospitalized in a rheumatology clinic between January 2010 and January 2011 were retrospectively analyzed. The patients were classified into two main groups: those with previously diagnosed underlying rheumatic disease (RD) and those without. The groups were analyzed for the final distribution of definitive diagnoses.
  
  
  RESULTS
  Out of 112 patients in the general study population, 47 had a previous RD and 65 had no previous history of RD. In these 65 patients, the most common etiology of nonspecific elevations in ESR/CRP levels was new onset RD (52.3%). Polymyalgia rheumatica (PMR) was the most common new onset RD (38% of all new onset RD) followed by seronegative rheumatoid arthritis. The incidences of infections and malignancies were 24.6% and 9.2%, respectively. CRP levels were significantly higher in infections when compared with new onset RD or malignancies (p<0.05). In patients with previous RD, the flare of the underlying disease was the most common etiology of nonspecific elevations in ESR/CRP levels (n=39, 83%, 20 female/19 male).
  
  
  CONCLUSIONS
  Extraordinarily high levels of serum CRP in a patient with nonspecific clinical findings should raise suspicion for non-rheumatic diagnoses, such as infection and malignancy, even in the presence of a previously diagnosed RD. Advanced radiological investigation is justified in these cases to rule out malignancy.
authors.affiliation: Department of Rheumatology, Division of Internal Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Berivan
authors.initials: B
authors.lastname: Bitik
authors.affiliation: Department of Rheumatology, Division of Internal Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Rıdvan
authors.initials: R
authors.lastname: Mercan
authors.affiliation: Department of Rheumatology, Division of Internal Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Abdurrahman
authors.initials: A
authors.lastname: Tufan
authors.affiliation: Department of Rheumatology, Division of Internal Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Engin
authors.initials: E
authors.lastname: Tezcan
authors.affiliation: Department of Rheumatology, Division of Internal Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Hamit
authors.initials: H
authors.lastname: Küçük
authors.affiliation: Department of Public Health, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: İlhan
authors.affiliation: Department of Rheumatology, Division of Internal Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Mehmet Akif
authors.initials: MA
authors.lastname: Öztürk
authors.affiliation: Department of Rheumatology, Division of Internal Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Seminur
authors.initials: S
authors.lastname: Haznedaroğlu
authors.affiliation: Department of Rheumatology, Division of Internal Medicine, Gazi University Faculty of Medicine, Ankara, Turkey.
authors.forename: Berna
authors.initials: B
authors.lastname: Göker
keywords: Blood sedimentation; C-reactive protein; rheumatology