Conclusions
AGP captured the influence of the APR on iron indicators and their relationships with each other. The APR influenced SF and its relationship with Hb as expected. TfR behaved unexpectedly. Although TfR has been promoted as an iron indicator that is uninfluenced by the APR, TfR concentrations were depressed among anemic APR-positive women. Because TfR reflects iron deficiency and erythropoietic activity, pro-inflammatory cytokines associated with the APR may be inhibiting erythropoiesis, which is reflected by lower TfR concentrations. We support the WHO/CDC recommendation that AGP is a useful indicator to assess the influence of the APR on iron status indicators.
Results
SF was significantly higher in APR-positive (AGP>1 g/l) women (P<0.001), in whom there was no association between SF and Hb. TfR was inversely associated with Hb, in both APR-positive and APR-negative women (P<0.001). However, among anemic women (Hb<110 g/l), APR-positive women had marginally lower TfR concentrations (P=0.053). There was no difference in EPO response to decreasing Hb among APR-positive and APR-negative women. Conclusions: AGP captured the influence of the APR on iron indicators and their relationships with each other. The APR influenced SF and its relationship with Hb as expected. TfR behaved unexpectedly. Although TfR has been promoted as an iron indicator that is uninfluenced by the APR, TfR concentrations were depressed among anemic APR-positive women. Because TfR reflects iron deficiency and erythropoietic activity, pro-inflammatory cytokines associated with the APR may be inhibiting erythropoiesis, which is reflected by lower TfR concentrations. We support the WHO/CDC recommendation that AGP is a useful indicator to assess the influence of the APR on iron status indicators.