Can C-Reactive Protein be Used As a Surrogate Marker of IL-6 in a Broad Array Of Clinical Entities?
Syed B. Ali, Amelia Cecchin, Cristina Lucchesi, Trishni Putty, Suzanne Edwards, Tina Petrou, Penelope Coates, Antonio Ferrante, Phillippa A. Pucar, Jovanka King, Tatjana Banovic
Abstract
Background: C-reactive protein (CRP) is commonly performed, whereas cytokine testing is limited to research. Aims: To determine CRP correlation to cytokines IL-6, IL-1β and TNF-α. Results: Consecutive samples (n = 307) were collected over 24 h. Ninety-six patients (31%) had acute infections, and 23 patients (7.5%) had autoimmune or inflammatory disease presentations. A strong correlation between CRP and two IL-6 assays (r = 0.74 and r = 0.71; p < 0.001) was present. CRP did not correlate with IL-1β and TNF-α across the data set. Bacterial infection had a significantly higher CRP and IL-6 (p < 0.001), while only CRP was elevated in inflammatory and autoimmune diseases (p < 0.001). Discussion: CRP may be used as a surrogate marker of IL-6 levels in the routine diagnostic laboratories.