Profiles of the acute-phase reactants C-reactive protein and ferritin related to the disease course of patients with systemic lupus erythematosus

Objective: To obtain insight in the acute-phase response in SLE. Methods: The clinical history, SLEDAI, CRP and ferritin concentrations were analysed throughout the disease course of 10 SLE patients. Results: During a mean follow-up of 4.8 years, 10 exacerbations (SLEDAI ≥11) occurred. Throughout the disease course, CRP and SLEDAI correlated positively in 5 patients, whereas the correlation between SLEDAI and ferritin was positive in 7 patients. However, elevated CRP concentrations together with elevated ferritin levels were only observed during 4 exacerbations. Ferritin concentrations were exceptionately high (> 1500 μg/L) during 4 flare-ups. CRP and ferritin levels remained normal during 5 exacerbations. Conclusion: SLE is characterised by highly variable and unusual CRP and ferritin responses that do not always reflect the extent of inflammation in individual patients. Despite severe disease activity, ferritin levels can remain well within the normal range, limiting its clinical usefulness as a marker for disease activity.