Inverse correlation of CRP and serum iron in patients with simple Community-acquired pneumonia (CAP)

The inflammatory response associated with infection, synthesis acute phase proteins (APPs), shifts iron from the circulation into storage in order to protect the organism. The prospective study included 47 patients (15 female, 32 male) with simple Community-acquired pneumonia (CAP) (mean age 62.4 ± 15.4 years). The patients did not use the supplementary iron therapy. We measured the white blood cell count (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), total iron binding capacity (TIBC), serum iron and calculated transferrin. Blood samples were analyzed on the first day (group I) and after 6-8 days of hospitalization (group II). The aim of the investigation was to describe segmental changes and correlation of APPs and serum iron during the diagnostic work-up and antibiotic treatment. CRP (166.95 ± 79.04 mg/L) showed decrease in group II (28.68 ± 26.59 mg/L) (p 0.001). WBC showed significant decrease (10.67 ± 3.6 vs. 7.9 ± 2.23x10³/ml). Serum iron showed negative linear correlation with CRP (r = -0,625; p<0.01) and positive correlation with TIBC (r = + 0.633; p<0.01). Serum CRP falls rapidly along with infection subsiding, while transferrin increases. Iron deficiency is common in patients with CAP. It positively correlates with transferrin, and negatively with CRP. The organism temporary responds to infection with hypoferremia, so that iron supplementation during CAP is unnecessary.