Does high ferritin with normal transferrin saturation indicate metabolic or inflammatory stress rather than iron overload?

Serum ferritin serves as both an iron-storage protein and a sensitive positive acute-phase reactant, making its elevation a complex clinical marker. When elevated ferritin is paired with a normal transferrin saturation (TSAT), it typically signals metabolic or inflammatory stress rather than true systemic iron overload.

Clinical and diagnostic findings

• Diagnostic differentiation: A normal TSAT (typically <45%) in the presence of hyperferritinemia effectively excludes classic hereditary hemochromatosis and significant parenchymal iron overload, directing the clinical focus toward metabolic management.
• Metabolic hyperferritinemia: This discordant pattern (high ferritin, normal TSAT) is the hallmark of dysmetabolic iron overload syndrome (DIOS). It is highly associated with insulin resistance and chronic low-grade inflammation, affecting up to 30% of patients with metabolic dysfunction-associated steatotic liver disease (MASLD/NAFLD).

Mechanistic pathways

• Cytokine-driven synthesis: Pro-inflammatory cytokines (IL-6, TNF-α, and IL-1β) activate JAK/STAT3, NF-κB, and Nrf2 pathways, upregulating ferritin transcription in hepatocytes and macrophages independently of systemic iron levels.
• Hepcidin-mediated sequestration: IL-6 stimulates hepatic hepcidin expression, which triggers the internalization and degradation of the iron exporter ferroportin. This blocks iron export and traps iron inside macrophages and hepatocytes, expanding intracellular ferritin storage.
• Cellular leakage: Passive leakage of intracellular ferritin from damaged hepatocytes during metabolic stress further raises serum levels, where circulating H-ferritin can bind to hepatic stellate cells to promote pro-inflammatory signaling and fibrogenesis.

Bottom line

• An elevated serum ferritin level paired with a normal transferrin saturation (<45%) clinically rules out genetic hemochromatosis and instead points to metabolic and inflammatory stress, such as MASLD/NAFLD, driven by cytokine-induced cellular iron trapping and hepatocyte leakage.