HAMP and vitamin D deficiency: Multiple observational studies report the association between vitamin D deficiency, high hepcidin levels and anemia in conditions characterized by inflammatory processes such as inflammatory bowel disease, acute infectious disease, severe traumatic injury and healthy preterm infants [127,128,129,130], while in other cases, vitamin D and iron deficiencies did not correlate with high hepcidin levels, even in the presence of inflammation [131].