Iron is essential for human life. It helps red blood cells transport oxygen and supports cellular energy production, but the body must regulate it carefully. Too much circulating iron can damage tissues, while too little can interfere with healthy red blood cell production. A small peptide hormone called hepcidin helps control this balance. Produced mainly by liver cells, hepcidin consists of just 25 amino acids. It is the central regulator of systemic iron distribution. Its primary target is ferroportin, a protein that transports iron out of cells into the bloodstream, found in intestinal cells that absorb dietary iron and in macrophages that recycle iron from aging red blood cells. When hepcidin binds to ferroportin, the transporter is internalized and degraded, so less iron enters the bloodstream from the intestine and from recycled sources. This lets the body reduce circulating iron when its supply is already sufficient. Hepcidin production responds to changing conditions. Increased iron levels stimulate it, and inflammation can raise it through interleukin-6 signaling. During increased red blood cell production, however, it is suppressed, partly through erythroferrone, which signals the body's increased demand for iron. The consequences are significant. Excessive hepcidin can restrict iron availability and contribute to anemia associated with chronic inflammation. Insufficient hepcidin can allow excessive iron absorption and contribute to iron-overload disorders such as hereditary hemochromatosis. Hepcidin shows how a small peptide can coordinate a major physiological system by controlling the movement of an essential mineral. https://peptidesatlanta.net/