Hepcidin concentrations can also become dysregulated as a consequence of diseases that affect iron absorption from the diet or cause a loss of blood from the body (each 1 mL of packed erythrocytes represents about 1 mg of iron), produce systemic inflammation, make erythropoiesis ineffective (lots of erythrocyte precursors but few mature) or cause anemia requiring erythrocyte transfusions without matching blood loss. This evidence concerns the gene HAMP and anemia.