Hepcidin production by the liver is disrupted by liver injury or inflammation.

The hepatic synthesis of hepcidin and its role as the master regulator of systemic iron homeostasis are well-established, with extensive research confirming that liver injury or inflammation disrupts this signaling axis.

Clinical evidence and mechanisms of action

The liver is the primary site of hepcidin production, specifically within hepatocytes. This synthesis is controlled by transcriptional pathways that integrate systemic signals, most notably the BMP/SMAD pathway for iron sensing and the IL-6/STAT3 pathway for inflammatory responses.

• Acute liver injury response: During acute injury (e.g., acetaminophen toxicity), hepcidin expression can increase 2- to 5-fold. This is driven by elevated IL-6 levels, which activate the JAK/STAT3 pathway to sequester iron, potentially protecting the liver from oxidative stress.
• Chronic liver disease variations: In chronic conditions like Hepatitis C (HCV), hepcidin is often suppressed despite active inflammation, possibly due to direct viral interference with HAMP transcription. Conversely, conditions such as Hepatitis B and NAFLD often show increased hepcidin levels as the disease progresses toward cirrhosis.
• The Hepcidin-Ferroportin axis: Hepcidin regulates iron flux by binding to ferroportin (FPN1), the only known cellular iron exporter. It induces ferroportin internalization and degradation, effectively "locking" iron inside cells.

Impact on iron distribution and absorption

Disrupting the hepcidin-ferroportin interaction has immediate systemic consequences on how iron is absorbed and distributed throughout the body.

• Intestinal absorption: When hepcidin signaling is low, ferroportin remains active on duodenal enterocytes, which can lead to a 5- to 10-fold increase in dietary iron absorption compared to normal levels.
• Macrophage sequestration: In the reticuloendothelial system, macrophages recycle iron from old red blood cells. High hepcidin levels (common in inflammation) block iron release from these macrophages, causing functional iron deficiency in the blood while macrophage stores remain high.
• Systemic redistribution: Disrupted signaling shifts iron distribution. Low hepcidin levels frequently result in transferrin saturation (TSAT) exceeding 80–100%, causing iron to deposit in parenchymal tissues—especially the liver and heart—rather than being sequestered safely in macrophages.

Bottom line

Hepcidin is the central regulator of iron, and its production in the liver is highly sensitive to injury. Disruptions to this signaling directly alter iron absorption and macrophage release, leading to significant systemic redistribution and potential tissue damage.