RESUMEN
Aim: To assess whether a significant correlation exists with serum Interleukin-6 cytokine levels in patients with Classic Fever of Unknown Origin (FUO) compared with healthy controls. The levels of IL-6 cytokine were tested as a proinflammatory cytokine which may belong to microorganisms that cause disease. Study Design: This is a case control, single center study. Place and Duration of Study: The study was conducted in the University of Maiduguri Teaching Hospital, Maiduguri, Borno State, Nigeria in patients with classic FUO who were treated between 2009 and 2012 were included in this study. Methodology: A total of 75 patients with classic FUO within the age range of 15 – 65 years were tested for IL-6 cytokine in comparison with 75 healthy controls. The sample size was calculated using Fisher’s formula. Results: In patients with FUO, 39% of patients demonstrated elevated levels of IL-6 while 20% of healthy controls demonstrated elevated levels (>200 pg/ml) of serum IL-6, while 12% and 15% respectively were in standard range of 0 - 6.4 pg/ml which is considered low. Gender differences were noted and mean values of IL-6 were higher in males (FUO mean±SD 136.7±161.8; Healthy controls mean±SD 132.3±183.5) than in females (FUO mean±141.6±133.9; Healthy controls mean±SD 97.8±134.2). Healthy male control had a value of 520.5 pg/ml with little difference to the male patients with FUO (575 pg/ml), p=0.91) while IL-6 concentrations in the female group who had FUO (407.5 pg/ml vs 367.5 pg/ml, p=0.16) showed greater difference in value in comparison to the healthy which trended towards statistical significance. We found that most patients (39%) with FUO have higher values of ≥ 200 pg/ml than the healthy controls. Conclusions: Serum IL-6 cytokine level is generally higher in males than in females and most patients (39%) with FUO have a higher value of ≥ 200 pg/ml than the healthy controls. IL-6 levels trended towards statistical significance and may help to discriminate females with FUO as compared their healthy controls.