This dispatch covers Your Ferritin Is 300 and Your Doctor Says You're Fine — That's Not Normal, That's the Problem in the research research category, authored by The Peptide Dispatch Editorial Team. Estimated reading time: 9 minutes. The Peptide Dispatch curates peer-reviewed peptide research for self-directed learners. All summaries are presented for Research Use Only and do not constitute medical advice.
## The marker your annual physical almost never orders Walk into a routine physical in the United States and ask for a "complete iron panel." Most primary care providers won't order one unless you're female, pregnant, or visibly anemic. A standard CBC measures hemoglobin and hematocrit — that tells you whether your red blood cells are carrying oxygen today. It does not tell you anything about how much iron is sitting in storage inside your liver, your heart, your pancreas, and your endocrine tissue. Ferritin does. And in men over 35, ferritin is one of the most underused predictive markers in the entire blood panel. The conventional reference range for men is roughly **20 to 336 ng/mL**, depending on the lab. The functional range — the range at which longevity research and metabolic studies suggest the body is operating without excess iron load or chronic inflammation — is much narrower: **roughly 60 to 120 ng/mL** in men. That gap is where chronic disease quietly accumulates for years before any other marker on a basic metabolic panel ever moves. ## What ferritin actually is — and why it does two jobs Ferritin is a protein that stores iron inside cells. When the body absorbs more iron than it immediately needs, it packages the excess into ferritin and warehouses it primarily in liver tissue. A small fraction of that stored ferritin leaks into the bloodstream, and the serum ferritin concentration is what shows up on a lab report. That's the iron-storage role. But ferritin has a second job that makes interpretation tricky: it is also an **acute-phase reactant**, meaning it rises in response to systemic inflammation. When the immune system is activated — by infection, injury, metabolic stress, visceral adiposity, autoimmune flare, or chronic low-grade inflammation — the liver upregulates ferritin production as part of a defensive iron-sequestration response. Pathogens need iron to replicate. Hiding iron away in ferritin is a useful short-term defense. The pro…
All information is presented for Research Use Only (RUO). Not medical advice.