What the hepcidin test shows
Hepcidin is the liver hormone that controls where iron goes — the master switch of iron balance. It binds to ferroportin, the only protein that exports iron from cells, and forces it to be broken down. When hepcidin is high, that door closes: less iron is absorbed from food and less is released from the liver and from macrophages recycling old red blood cells. When it is low, the door stays open and iron flows into the blood (StatPearls: Physiology, Hepcidin).
This sets hepcidin apart from the iron markers measured first. Ferritin shows how much iron is stored; serum iron and transferrin saturation show how much circulates now. Hepcidin tells you why iron is moving that way — whether the body is holding it back or letting it through — so it can explain contradictory results such as low blood iron despite full stores (Nemeth & Ganz, 2023).
Hepcidin normal range
Hepcidin is reported in conventional units (ng/mL) and SI units (nmol/L); to convert, ng/mL × 0.36 ≈ nmol/L (equivalently, nmol/L × 2.79 ≈ ng/mL). Levels track iron stores, so they tend to be lower in menstruating women and rise after menopause. The orientation values below come from a large general-population study measured by mass spectrometry.
| Group | Conventional (ng/mL) | SI (nmol/L) |
|---|---|---|
| Men, adult | ~1.7–65 | ~0.6–23.3 |
| Women, premenopausal | ~1.1–55 | ~0.4–19.7 |
| Women, postmenopausal | ~3.3–69 | ~1.2–24.8 |
There is still no international reference standard for hepcidin, and different methods can give values that differ several-fold — immunoassays commonly read higher than the mass-spectrometry values above. So these numbers are orientation only — even more than for most tests, read your result against the range printed on your own lab’s report (Galesloot et al., Blood 2011).
Why hepcidin is high
High hepcidin means the body is actively locking iron away. Ordered roughly by how often it is seen:
- Inflammation and infection (most common). Inflammatory signals — above all the cytokine interleukin-6 — drive the liver to release hepcidin, pulling iron out of the blood and trapping it in cells, partly to starve invading microbes of iron. Sustained, this causes anemia of inflammation (anemia of chronic disease), the most common anemia in hospitalized and chronically ill people (Weiss, Ganz & Goodnough, Blood 2019).
- Chronic kidney disease. Reduced clearance and inflammation raise hepcidin, feeding the iron-restricted anemia common in kidney disease.
- Iron overload. As stores fill, hepcidin rises to shut off absorption — normal feedback, e.g. after repeated transfusions.
- Iron-refractory iron deficiency anemia (IRIDA). A genetic condition (TMPRSS6 mutations) with inappropriately high hepcidin despite iron deficiency, so oral iron barely works.
- Cancer and obesity. Both are low-grade inflammatory states that can push hepcidin up.
Hepcidin itself is rarely an emergency number, but a high value with fever, unexplained weight loss, or worsening anemia warrants a prompt doctor visit to find the cause.
Why hepcidin is low
Low hepcidin is usually the body doing the right thing when it needs iron — the switch turns off so the gut absorbs more and stores are released.
- Iron deficiency (most common). As stores fall, hepcidin drops to maximize absorption. This is the expected, healthy direction in early iron deficiency and iron-deficiency anemia (Camaschella, NEJM 2015).
- Busy red-cell production. When the marrow works hard — after bleeding, at high altitude, in pregnancy, or in thalassemia — young red-cell precursors release a hormone called erythroferrone that suppresses hepcidin to free up iron.
- Low oxygen (hypoxia). A low-oxygen state pushes the body to make more red cells and lowers hepcidin to supply the iron.
- Hereditary hemochromatosis. In the common HFE-related form, hepcidin is inappropriately low for the body’s iron load, so absorption never switches off and iron slowly builds up — potentially harming the liver, heart, and pancreas over years.
Act sooner if hepcidin is very low together with a high ferritin or transferrin saturation: that pattern raises the question of iron overload, which deserves timely evaluation to protect the organs.
What to test alongside
Hepcidin is almost never read on its own. The markers that give it meaning:
- Ferritin — iron stores; both rise with inflammation, so they are read together.
- Serum iron — the iron circulating now, which high hepcidin drives down.
- Transferrin saturation — the filled share of iron-carrying capacity; key for both deficiency and overload.
- TIBC and transferrin — iron-carrying capacity, which climbs in iron deficiency.
- Soluble transferrin receptor — rises in true iron deficiency but not in inflammation, helping separate iron-deficiency anemia from anemia of inflammation.
- CRP — an inflammation marker; a high CRP flags the states that push hepcidin up.
- Hemoglobin — shows whether an iron problem has already caused anemia.
What to do about an abnormal result
- Do not self-treat. Iron supplements can do harm if the real problem is iron overload or inflammation. Never start or stop iron on the strength of a hepcidin number alone.
- Read it in context. Ask your doctor to interpret hepcidin with ferritin, transferrin saturation, CRP, and a full blood count; the pattern matters more than any single value.
- Repeat when well. Because inflammation moves hepcidin, a value taken during infection or a flare may not reflect your baseline; repeat after you recover.
- Find the cause. For a low-iron picture, look for a source of blood loss; for an iron-overload picture, evaluate for hemochromatosis and its organ effects.
- See the right doctor. Start with your primary care doctor or internist. Persistent or complex iron problems are referred to a hematologist; suspected hemochromatosis may also involve a gastroenterologist or hepatologist.
Mini-FAQ
What does a high hepcidin level mean?
High hepcidin usually reflects inflammation, infection, or true iron overload. It blocks iron absorption and locks iron inside cells, which can cause low blood iron and anemia of inflammation even when body stores are full.
What does a low hepcidin level mean?
Low hepcidin is the body’s normal response to iron deficiency, anemia, or a low-oxygen state — it opens the gates so you absorb and release more iron. Persistently low hepcidin can also point to genetic iron overload (hemochromatosis).
Is hepcidin a routine blood test?
No. Ferritin, transferrin saturation and CRP are the routine first-line iron tests. Hepcidin is a specialized test used mainly in research and in difficult cases, and it is not yet standardized across labs.
Can hepcidin explain why oral iron isn’t working?
Yes. High hepcidin blocks iron absorption from the gut, so oral tablets may not raise your levels. When inflammation keeps hepcidin high, doctors often switch to intravenous iron, which bypasses the gut. And because even a single oral dose briefly raises hepcidin, alternate-day dosing can improve how much iron you absorb.
Why do hepcidin reference ranges vary so much between labs?
There is no international reference standard for hepcidin yet, so each method (mass spectrometry or immunoassay) produces different numbers. Always compare your result with the range printed on your own lab’s report.
