Effects of Intravenous Versus Oral Iron Replacement on Inflammatory Markers and Serum Uric Acid in Premenopausal Women with Iron Deficiency: A Prospective Study

Background/Objectives: Iron deficiency may be associated with alterations in systemic inflammatory activity and metabolic parameters. However, whether oral and intravenous (IV) iron replacement have different effects on inflammatory markers and serum uric acid remains unclear. We compared inflammatory and metabolic responses to oral and IV iron in premenopausal women with iron deficiency. Methods: This prospective observational study included 72 oral iron recipients, 77 IV iron recipients, and 76 healthy controls. Patients were reassessed at Day 30. The primary outcome was change in C-reactive protein (CRP); changes in erythrocyte sedimentation rate (ESR) and uric acid were secondary outcomes. Additional regressions used robust standard errors, adjusting for age, baseline hemoglobin, and baseline outcome values; the uric acid model additionally included baseline creatinine. Results: Baseline CRP and ESR were significantly higher in both iron-deficient groups than in controls (all Bonferroni-adjusted p < 0.001). The IV iron group had more severe baseline anemia than the oral iron group (median hemoglobin: 8.60 vs. 10.70 g/dL; Bonferroni-adjusted p < 0.001). Increases in hemoglobin, ferritin, and transferrin saturation over 30 days were greater with IV iron (all p < 0.001). Median CRP changes were −0.22 mg/L with IV iron and 0.07 mg/L with oral iron (unadjusted p = 0.041). However, multivariable regression with robust standard errors showed no statistically significant difference in Day 30 CRP after adjustment for age, baseline hemoglobin, and baseline CRP (IV minus oral: −1.585 mg/L; 95% CI, −3.261 to 0.091; p = 0.064; n = 149). The corresponding adjusted analysis showed lower Day 30 ESR with IV iron (−2.118 mm/h; 95% CI, −3.817 to −0.418; p = 0.015; n = 91). The adjusted serum uric acid difference, additionally accounting for baseline creatinine, was not statistically significant (0.389 mg/dL; 95% CI, −0.009 to 0.787; p = 0.055; n = 149). Conclusions: IV iron was associated with greater hematologic and iron-store repletion over 30 days. Adjusted comparisons showed no statistically significant differences in CRP or serum uric acid, whereas ESR was modestly lower with IV iron, with uncertain clinical significance. Nonrandomized treatment allocation and premedication restricted to the IV group preclude attributing these findings solely to iron administration.