Plasma Ferritin and Hepcidin Are Lower at 4 Months Postpartum among Women with Elevated C-Reactive Protein or α1-Acid Glycoprotein

Background: Ferritin and hepcidin are markers of iron status that typically increase during inflammation or infection. The postpartum period is a physiologically unique life stage in which the relations between these proteins and other markers of inflammation have not been extensively studied. Objective: We aimed to determine whether 2 markers of inflammation [high-sensitivity C-reactive protein (CRP) and α1-acid glycoprotein (AGP)] were associated with ferritin or hepcidin in postpartum women in California. Methods: This is a secondary analysis of a randomized controlled iron-intervention trial. Plasma CRP, AGP, ferritin, and hepcidin were analyzed at 2 and 17 wk postpartum in 114 lactating women. We examined Pearson correlation coefficients between all biomarkers at both time points and differences in mean values of ferritin and hepcidin between those with and without elevated CRP and/or AGP. Results: At 2 and 17 wk postpartum, 58% and 26% of women had CRP >5 mg/L and 78% and 29% had AGP >1 g/L, respectively. Neither CRP nor AGP was significantly correlated with ferritin ( r = 0.07 and -0.06; n = 114 at 2 wk; -0.14 and -0.14; n = 95 at 17 wk) or hepcidin ( r = 0.18 and -0.03 at 2 wk; -0.05 and -0.14 at 17 wk; P > 0.05 for all). At 2 wk, geometric mean plasma ferritin and hepcidin concentrations did not differ between women with and without elevated CRP or AGP ( P > 0.5), but at 17 wk women with elevated CRP or AGP had lower mean (95% CI) ferritin and hepcidin than did women without either elevated CRP or AGP [ferritin: 30.3 ng/mL (23.4, 39.1 ng/mL) compared with 40.2 ng/mL (32.9, 49.2 ng/mL); P < 0.01; hepcidin: 44.3 ng/mL (32.3, 60.9 ng/mL) compared with 67.6 ng/mL (56.1, 81.5 ng/mL); P = 0.02]. Conclusion: Lower ferritin and hepcidin among women with elevated CRP or AGP at 17 wk postpartum suggests that these markers of iron status react differently to physiologic immune activation than to pathologic inflammatory states.