Hepcidin: Understanding Your Blood Test Series

1. Overview: What this test reveals and why it is important

Hepcidin is a peptide hormone produced primarily by the liver that serves as the master regulator of systemic iron homeostasis. Discovered in 2001, it has revolutionised our understanding of iron metabolism and its disorders .

Hepcidin exerts its regulatory function by controlling the only known cellular iron exporter, ferroportin, which is located on the membrane of macrophages, hepatocytes, and the basolateral surface of enterocytes . When hepcidin binds to ferroportin, it induces internalisation and degradation of this transporter, resulting in:

· Decreased dietary iron absorption from the gut.

· Increased intracellular iron sequestration in macrophages and hepatocytes.

· Reduced circulating iron concentrations, limiting iron availability for erythropoiesis .

Clinical utility:

· Differentiating causes of anaemia: Hepcidin helps distinguish iron deficiency anaemia (low hepcidin) from anaemia of chronic disease/inflammation (high or inappropriately normal hepcidin) .

· Diagnosing iron disorders: Low hepcidin characterises hereditary haemochromatosis; high hepcidin defines iron-refractory iron deficiency anaemia (IRIDA) .

· Guiding iron therapy: Hepcidin levels may predict response to oral versus intravenous iron supplementation .

· Monitoring inflammatory conditions: As an acute‑phase protein, hepcidin rises with inflammation and correlates with disease activity in conditions like inflammatory bowel disease .

Important principle: Hepcidin measurement is not yet routine clinical practice due to assay limitations and lack of standardisation . Its interpretation always requires concurrent measurement of iron studies (ferritin, iron, transferrin saturation), inflammatory markers (CRP), and renal function (eGFR) .

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2. What does it measure

a. Units of measurement

· Nanograms per millilitre (ng/mL) – common for ELISA assays.

· Nanomoles per litre (nmol/L) – used in mass spectrometry-based methods .

· Conversion: Varies by assay; approximately 1 nmol/L ≈ 2.7 ng/mL (based on molecular weight 2.7 kDa).

b. Normal Range and Interpretation

(Reference ranges vary significantly by assay method, age, sex, and population; the following are general guidelines from research studies .)

Adults (healthy, no inflammation, normal iron stores):

· Hepcidin-25: 1–25 nmol/L (approximately 2.7–67.5 ng/mL)

· Women tend to have lower levels than men due to lower iron stores.

Iron deficiency:

· Very low to undetectable (<1 nmol/L) .

Inflammation (CRP >10 mg/L):

· Elevated, often >20–40 nmol/L; wide inter-individual variation .

Chronic kidney disease (eGFR <30 mL/min):

· Markedly elevated due to reduced renal clearance; median ~7.4 nmol/L but with large variance .

Hereditary haemochromatosis:

· Inappropriately low relative to iron stores .

Iron-refractory iron deficiency anaemia (IRIDA):

· Inappropriately high despite iron deficiency .

Interpretation notes:

· The log[hepcidin]:log[ferritin] ratio (hepcidin index) may discriminate iron deficiency from inflammation: iron deficiency shows a notably lower index (e.g., –0.66 vs 0.3 in controls) .

· Hepcidin-25 is the bioactive form; other isoforms (hepcidin-20, -22) are degradation products with unknown clinical significance, though hepcidin-20 may rise acutely in myocardial infarction .

· Hepcidin testing is not warranted in patients with active infection, inflammatory autoimmune conditions (CRP >10 mg/L), or severe renal dysfunction (eGFR <30 mL/min) due to confounding effects .

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3. Other factors connected to this

a. Direct correlation (factors that directly influence hepcidin levels)

Factors that INCREASE hepcidin:

· Iron loading: Elevated transferrin saturation stimulates hepcidin production to limit further iron absorption.

· Inflammation:

· Interleukin-6 (IL-6) is the primary cytokine driving hepcidin synthesis in the liver .

· Acute and chronic inflammatory conditions: infections, autoimmune diseases, inflammatory bowel disease, rheumatoid arthritis, vasculitis.

· Renal dysfunction:

· Hepcidin is cleared by the kidneys; eGFR <30 mL/min significantly elevates levels .

· Obesity: Adipose tissue produces inflammatory cytokines that stimulate hepcidin.

· Neoplastic diseases: Many cancers elevate hepcidin via inflammatory mediators .

Factors that DECREASE hepcidin:

· Iron deficiency: Low iron stores suppress hepcidin to enhance iron absorption and mobilisation .

· Hypoxia: Low oxygen tension downregulates hepcidin to increase iron availability for erythropoiesis.

· Erythropoietic activity:

· Erythroferrone, produced by erythroblasts, suppresses hepcidin to meet iron demands for haemoglobin synthesis .

· Conditions with ineffective erythropoiesis (thalassaemia, myelodysplasia) suppress hepcidin.

· Genetic disorders:

· Hereditary haemochromatosis (HFE, TFR2, HJV, HAMP mutations) – impaired hepcidin production or signalling leads to iron overload .

· TMPRSS6 mutations (IRIDA) – inappropriately elevated hepcidin due to impaired suppression .

· Blood loss: Haemorrhage stimulates erythropoiesis and suppresses hepcidin.

b. Indirect correlation (factors that influence hepcidin interpretation)

· Timing of test: Hepcidin exhibits diurnal variation (higher in the morning); fasting morning samples are preferred.

· Sample handling: Hepcidin is stable in serum/plasma but haemolysis affects results; samples should be processed promptly .

· Assay variability:

· Mass spectrometry (HPLC/MS/MS): Gold standard; specific for hepcidin-25 .

· ELISA: More widely available but may lack specificity for hepcidin-25 and show cross-reactivity with other isoforms .

· Standardisation is ongoing but not yet universal .

· Age: Hepcidin levels are low at birth and rise during childhood; elderly may have higher levels due to subclinical inflammation.

· Pregnancy: Hepcidin decreases in pregnancy to support fetal iron needs.

· Medications:

· Erythropoiesis-stimulating agents (ESA) – suppress hepcidin.

· Iron supplementation – may increase hepcidin (dose-dependent).

· Anti-inflammatory biologics (anti-IL-6, anti-TNF) – may lower hepcidin by reducing inflammation.

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4. Disorders related to abnormal values

a. When hepcidin is low (inappropriately low)

Hereditary haemochromatosis (HH):

· Types 1–4: Genetic defects in HFE, TFR2, HJV, or HAMP lead to insufficient hepcidin production or signalling.

· Features: Iron overload, elevated transferrin saturation, elevated ferritin, tissue deposition (liver, heart, pancreas, joints).

· Hepcidin deficiency causes increased iron absorption and macrophage iron release .

Iron deficiency anaemia (IDA):

· Physiological suppression: Low iron stores signal the liver to reduce hepcidin, enhancing iron absorption and mobilisation .

· Features: Low ferritin, low transferrin saturation, microcytic anaemia.

· Hepcidin is very low to undetectable in severe IDA.

Iron-loading anaemias:

· Thalassaemia syndromes, myelodysplastic syndromes, sideroblastic anaemia: Ineffective erythropoiesis produces erythroferrone, suppressing hepcidin despite iron overload.

· Features: Anaemia with elevated iron stores, transfusion dependence.

Chronic hepatitis C:

· Associated with low hepcidin, contributing to iron loading .

Hypoxia:

· High altitude, chronic lung disease, cyanotic heart disease.

b. When hepcidin is high (inappropriately high)

Anaemia of chronic disease / inflammation:

· Mechanism: IL-6 and other cytokines stimulate hepcidin production, causing iron retention in macrophages and decreased iron absorption .

· Features: Normocytic or microcytic anaemia, normal or elevated ferritin, low transferrin saturation.

· Common in: Rheumatoid arthritis, inflammatory bowel disease, chronic infections, malignancy, heart failure.

Iron-refractory iron deficiency anaemia (IRIDA):

· Rare genetic disorder: TMPRSS6 mutations impair matriptase-2, which normally suppresses hepcidin. Hepcidin is inappropriately elevated despite iron deficiency.

· Features: Hypochromic microcytic anaemia, very low transferrin saturation, normal/high hepcidin, poor response to oral iron, partial response to IV iron .

Chronic kidney disease (CKD):

· Reduced renal clearance of hepcidin, compounded by inflammation.

· Features: Anaemia of CKD, resistance to erythropoiesis-stimulating agents, elevated hepcidin .

Acute phase response:

· Infection, surgery, trauma, myocardial infarction – transient hepcidin elevation .

Neoplastic diseases:

· Many solid tumours and haematological malignancies elevate hepcidin via inflammatory cytokines .

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5. Best way to address aberrant levels

Important principle: Hepcidin is not directly treated. The underlying condition – iron deficiency, inflammation, genetic disorder, or renal disease – is treated. Hepcidin levels normalise as the underlying pathophysiology is corrected.

a. Quick ways or using Medications

For low hepcidin states:

· Iron deficiency anaemia:

· Oral iron: Ferrous salts (sulphate, fumarate, gluconate) – first-line. Hepcidin will rise as iron stores replenish.

· Intravenous iron: For severe anaemia, malabsorption, intolerance to oral iron. IV iron rapidly increases iron stores and hepcidin.

· Monitor: Ferritin, transferrin saturation, haemoglobin.

· Hereditary haemochromatosis:

· Phlebotomy: First-line treatment. Removes iron, reduces iron stores, and eventually hepcidin may rise (though often remains low).

· Target ferritin: 50–100 ng/mL .

· Iron chelation: Deferoxamine, deferasirox, deferiprone – for patients unable to tolerate phlebotomy.

· Monitoring: Ferritin, transferrin saturation, liver function, cardiac MRI for iron loading.

· Iron-loading anaemias:

· Iron chelation therapy to prevent iron overload complications.

· Erythroferrone modulation – investigational.

For high hepcidin states:

· Anaemia of chronic disease / inflammation:

· Treat underlying inflammatory condition: Disease-modifying antirheumatic drugs (DMARDs), biologics (anti-TNF, anti-IL-6), corticosteroids.

· Erythropoiesis-stimulating agents (ESA): Epoetin, darbepoetin – overcome hepcidin-mediated iron restriction.

· IV iron: May be effective if functional iron deficiency (low transferrin saturation despite normal/elevated ferritin).

· Investigational: Anti-hepcidin antibodies, anti-IL-6 antibodies, BMP6 inhibitors.

· Iron-refractory iron deficiency anaemia (IRIDA):

· IV iron: First-line therapy. Oral iron is ineffective.

· ESA: May be added in severe cases.

· Genetic counselling.

· Chronic kidney disease:

· ESA therapy – standard of care.

· IV iron – when transferrin saturation <30% and ferritin <500 ng/mL.

· HIF stabilisers (roxadustat, daprodustat): Novel oral agents that stimulate erythropoiesis and lower hepcidin by mimicking hypoxia.

· Inflammatory bowel disease:

· Treat IBD flare: Immunosuppression, biologics.

· IV iron – preferred over oral iron in active disease, as oral iron may exacerbate inflammation and is poorly absorbed due to high hepcidin .

Do not self-prescribe – all medications require specialist supervision.

b. Using Supplements or Holistic medicine

Supplements are adjunctive only; they do not replace definitive therapy. No supplement directly targets hepcidin, but several may modulate its levels indirectly.

For iron deficiency (low hepcidin):

· Iron supplements: As above. Choose well-tolerated forms.

· Preferred plant-based / fermentation-derived:

· Iron bisglycinate – chelated, well tolerated, fewer gastrointestinal side effects.

· Plant-derived iron supplements (from curry leaves, moringa, spirulina) – lower bioavailability; acceptable for mild deficiency.

· Enhance absorption: Take with vitamin C (citrus, amla, ascorbic acid supplement); avoid tea, coffee, calcium supplements within 1 hour.

· Vitamin C: Enhances non-heme iron absorption.

· Avoid: High-dose zinc (may interfere with iron absorption).

For inflammation (high hepcidin):

· Omega-3 fatty acids (EPA/DHA):

· Anti-inflammatory; may reduce IL-6 and thus hepcidin.

· Preferred source: Algae oil – sustainable, plant-based, direct EPA/DHA, no marine contaminants.

· Avoid conventional fish oil (overfishing, ocean pollution, ethical concerns).

· Dose: 2–4 g/day EPA/DHA.

· Curcumin (turmeric):

· Inhibits NF-κB and pro-inflammatory cytokines including IL-6.

· May indirectly lower hepcidin.

· Use phytosomal, liposomal, or with piperine for bioavailability.

· Avoid products with added synthetic folic acid or cyanocobalamin.

· Vitamin D:

· Immunomodulatory; deficiency correlates with higher inflammatory markers.

· May reduce hepcidin via anti-inflammatory effects.

· Preferred: D3 (cholecalciferol) from lichen.

· Dose: 600–2000 IU/day; higher for deficiency correction.

· Green tea catechins (EGCG):

· Anti-inflammatory; may reduce hepcidin expression.

· Use beverage (2–3 cups/day) rather than concentrated extracts (hepatotoxicity risk).

· Probiotics / prebiotics:

· Modulate gut microbiota; emerging evidence suggests they reduce systemic inflammation.

· Preferred sources: fermented plant foods (kimchi, sauerkraut, kombucha, miso, tempeh); standardised probiotic supplements.

For general iron metabolism support:

· Copper: Required for ferroxidase activity (ceruloplasmin); deficiency impairs iron mobilisation.

· Sources: Cashews, sunflower seeds, chickpeas, lentils, mushrooms.

· Supplement only if deficiency confirmed.

· B vitamins: Support erythropoiesis.

· Use methylcobalamin and methylfolate – active forms, avoid synthetic folic acid and cyanocobalamin.

Supplements to AVOID:

· Synthetic folic acid – avoid; use methylfolate.

· Cyanocobalamin – avoid; use methylcobalamin.

· High-dose zinc without medical supervision – may cause copper deficiency and impair iron metabolism.

· Unregulated herbal blends – hepatotoxicity risk; no proven benefit.

c. Using Diet and Foods (following a plant‑forward, ecologically sustainable approach)

Diet is a cornerstone of managing iron status and inflammation. A well-designed, nutrient-dense, anti-inflammatory plant-based diet can complement medical therapy.

Core dietary principles – what to emphasise:

· Iron-rich plant foods (for deficiency):

· Legumes: Lentils, chickpeas, kidney beans, black beans, soybeans, tofu, tempeh.

· Leafy greens: Cooked spinach, amaranth, moringa, kale, collards.

· Seeds: Pumpkin seeds, hemp seeds, sesame seeds (tahini).

· Nuts: Cashews, almonds.

· Whole grains: Quinoa, amaranth, fortified cereals.

· Dried fruits: Apricots, raisins, dates.

· Fungi: Shiitake mushrooms (dried have higher iron content).

· Algae: Spirulina, chlorella – acceptable as whole food.

· Iron absorption enhancers:

· Vitamin C: Citrus fruits, amla, guava, bell peppers, broccoli, tomatoes – include with iron-rich meals.

· Fermented foods: Kimchi, sauerkraut – may increase iron bioavailability.

· Iron absorption inhibitors (separate from iron-rich meals):

· Tea, coffee (tannins) – consume between meals.

· Calcium supplements / dairy – separate by 2 hours.

· Whole grains, legumes (phytates) – reduce by soaking, sprouting, fermentation.

· Anti-inflammatory diet (for high hepcidin states):

· Mediterranean-style plant-forward diet: Abundant vegetables, fruits, legumes, whole grains, nuts, seeds, olive oil.

· High in polyphenols, fibre, unsaturated fats.

· Low in refined carbohydrates, added sugars, saturated fats.

· Reduces inflammatory markers (IL-6, CRP) and may lower hepcidin.

· Omega-3 fatty acids:

· ALA sources: Ground flaxseeds, chia seeds, hemp seeds, walnuts.

· Direct EPA/DHA: Microalgae (spirulina, chlorella – limited amounts); algae oil supplements for therapeutic doses.

· Polyphenol-rich foods:

· Berries, green tea, dark chocolate (≥70% cocoa), extra virgin olive oil, turmeric, ginger, cruciferous vegetables, onions, garlic.

· Adequate protein intake:

· Essential for erythropoiesis and immune function.

· Plant-based protein sources (hierarchy adhered):

· Primary: Legumes, soy products (tofu, tempeh, edamame).

· Fungi / algae: Mycoprotein (Quorn), spirulina, chlorella.

· Biotechnology: Precision-fermented dairy proteins – acceptable emerging options.

· Dairy / eggs: Permitted but not emphasised; low-fat fermented dairy if tolerated.

· Meat, poultry, fish: Deliberately omitted. Effective plant-based alternatives exist.

What to avoid or severely limit:

· Ultra-processed foods, refined carbohydrates, added sugars – promote inflammation.

· Excess alcohol – may exacerbate inflammation and iron loading.

· Smoking – cessation is essential for reducing inflammation and improving iron status.

Lifestyle factors with proven benefit:

· Regular moderate exercise: Reduces chronic inflammation, improves iron utilisation.

· Stress reduction: Mindfulness, meditation, yoga, adequate sleep – lowers inflammatory cytokines.

· Weight management: Obesity promotes inflammation and elevates hepcidin.

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6. How soon can one expect improvement and the ideal time frame to retest

Hepcidin responds relatively rapidly to changes in iron status, inflammation, and renal function – within days to weeks.

For iron deficiency treated with iron supplementation:

· Oral iron: Hepcidin begins to rise within 1–2 weeks as iron stores increase; maximal effect at 4–8 weeks.

· IV iron: Hepcidin rises within 24–48 hours, peaks at 3–7 days, and may remain elevated for 2–4 weeks.

· Retesting: Not routinely performed; monitor ferritin and haemoglobin.

For inflammation treated with anti-inflammatory therapy:

· Corticosteroids / biologics: Hepcidin may decline within 1–4 weeks as inflammatory cytokines (IL-6) decrease.

· Retesting: Not routine; monitor CRP, ESR, and clinical disease activity.

For chronic kidney disease treated with ESA / HIF stabilisers:

· HIF stabilisers (roxadustat, daprodustat): Hepcidin declines within 2–4 weeks; maximal effect at 8–12 weeks.

· Retesting: Not routine; monitor haemoglobin, ferritin, transferrin saturation.

For hereditary haemochromatosis treated with phlebotomy:

· Hepcidin may remain low for years; eventual rise after iron depletion (ferritin <50 ng/mL) over 12–24 months.

· Retesting: Not indicated; monitor ferritin and transferrin saturation.

For research purposes:

· Hepcidin may be retested at 4–8 weeks intervals to assess response to novel therapies.

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Conclusion

Hepcidin is the master conductor of the iron orchestra – silencing ferroportin when iron is abundant, releasing it when iron is scarce. Its discovery has transformed our understanding of iron metabolism and provided a molecular explanation for the anaemia of inflammation, the iron overload of haemochromatosis, and the puzzling resistance to oral iron in IRIDA.

Yet hepcidin measurement remains, for now, a research tool rather than a routine clinical test. Assay standardisation is evolving, and interpretation requires nuanced integration of iron studies, inflammatory markers, and renal function. The log[hepcidin]:log[ferritin] ratio offers promise in complex cases, but clinical decision-making still rests on traditional parameters.

The treatment of hepcidin disorders is the treatment of the underlying condition: iron for deficiency, chelation or phlebotomy for overload, anti-inflammatories and ESAs for the anaemia of chronic disease. Novel therapies targeting hepcidin itself – monoclonal antibodies, BMP6 inhibitors, HIF stabilisers – are on the horizon and may one day allow direct modulation of this master regulator.

A plant-based, ecologically responsible diet – rich in legumes, whole grains, nuts, seeds, and algae-derived omega-3s – provides the anti-inflammatory nutritional foundation that supports optimal iron metabolism. It supplies iron in forms that, with careful preparation and pairing with vitamin C, can meet physiological needs. It avoids the pro-inflammatory load of animal products that might exacerbate hepcidin elevation in chronic disease. There is no requirement for meat; its displacement by plants is itself a therapeutic and ecological act.

Hepcidin is a number – a concentration, a level. The patient is a story of fatigue, pallor, dyspnoea, and resilience. Listen to the patient, not the number – but as hepcidin assays enter clinical practice, this number will increasingly illuminate the story.

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Note on dietary recommendations on this site:

For the sake of our environment we adhere to the following dietary preference hierarchy:

1. Plant‑based

2. Fungi / algae / fermented

3. Biotechnology / lab‑grown / cultures

4. Dairy / eggs

5. Meat / fish / poultry (only if no effective alternative exists)

Special notes on hepcidin and iron metabolism:

· Iron supplements: Choose well-tolerated forms (ferrous bisglycinate preferred). Take with vitamin C for enhanced absorption.

· Iron-rich plant foods: Lentils, chickpeas, tofu, pumpkin seeds, quinoa, fortified cereals, dark leafy greens.

· Enhance iron absorption: Soak, sprout, or ferment legumes and grains; pair with vitamin C; avoid tea/coffee with meals.

· Anti-inflammatory diet: Essential for managing high hepcidin states (inflammation, chronic disease).

· Monitor ferritin and transferrin saturation – not hepcidin – to guide therapy in clinical practice.

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