Associations between Serum Ferritin and Markers of Glucose Homeostasis and Inflammation in Overweight Young Women

Purpose: Serum ferritin is positively associated with insulin resistance, type 2 diabetes mellitus, and the metabolic syndrome; however, the mechanism underlying this association is not clear, as ferritin is a biomarker of both hepatic iron stores and of inflammation. The objectives of the present study were: 1) to examine the associations between serum ferritin concentrations and markers of inflammation and glucose homeostasis; and 2) to determine the acute changes in serum ferritin following ingestion of a High-Fat, High-Carbohydrate (HFHC) meal challenge in sedentary overweight/obese, but otherwise healthy, women. Methods: Overweight/obese, but otherwise healthy women (n=16), aged 18-45 years old, participated in this cross-sectional study. Blood was collected prior to and 1, 2, 4, and 6 hour after ingestion of a High-Fat, High-Carbohydrate (HFHC) meal. Inflammatory markers (interlukin-6, IL-6; tumor necrosis factor-α, TNF-α; IL-1β), ferritin, glucose and insulin concentrations were measured in fasting and postprandial blood samples and incremental Area Under Curve (iAUC) was calculated for the 6-hour postprandial period. Paired t-tests were used to determine if postprandial peak concentrations differed from fasting. Relationships between ferritin and markers of inflammation and glucose homeostasis (fasting, peak, iAUC) were evaluated using Pearson's correlation. Results: Postprandial peak glucose, insulin, IL-6, TNF-α, IL-1β, and ferritin concentrations were significantly greater than fasting; iAUC for IL-6, TNF-α, IL- 1β were positive. Ferritin was not correlated with cytokines, glucose or insulin; IL-6, TNF-α, and IL-1β were significantly correlated. Conclusion: In overweight, but otherwise healthy women, ferritin appears to be an indicator of iron stores rather than a marker of inflammation. Because ferritin is produced by the liver in response to IL-6,it is possible that we may have observed a greater increase in ferritin had we collected blood at later time points after the HFHC meal.