Ferritin

Ferritin is a protein that acts as the body’s main iron storage system. While a small amount circulates in your blood (this is the ferritin measured on your pathology report), most ferritin lives inside cells — especially in the liver, spleen, muscles, and bone marrow. Its job is simple but essential: it holds onto iron and releases it in a carefully regulated way so your body can make haemoglobin (the oxygen-carrying protein in red blood cells), support energy production, and fuel hundreds of metabolic reactions.

Iron is not something your body can create on its own — you must absorb it from food. Ferritin helps control this iron flow so that levels stay balanced. When ferritin is low, the body has very limited iron reserves, which means you may struggle to make enough haemoglobin. When ferritin is high, the body may be storing too much iron or reacting to inflammation, infection, or liver injury. Because ferritin rises in response to inflammation (an “acute-phase reactant”), it must always be interpreted in the context of overall health, symptoms, and related biomarkers such as haemoglobin, transferrin saturation, C-reactive protein (CRP), and liver enzymes.

Ferritin gives one of the clearest snapshots of your iron status and is often the earliest marker to change, long before haemoglobin drops. Tracking ferritin over time helps understand iron balance, nutritional needs, menstrual or gastrointestinal blood loss, and how your body responds to iron-rich foods or supplements.

Ferritin matters because iron is fundamental to life. Every cell in your body relies on oxygen, and without adequate iron stores, your red blood cells can’t carry enough oxygen to your tissues. This can result in fatigue, reduced exercise tolerance, shortness of breath, dizziness, cold intolerance, hair shedding, poor concentration, and lowered immunity. Low ferritin is the most specific marker of iron deficiency — even before anaemia develops. Levels below 15 ng/mL are diagnostic for iron deficiency in most adults, and values below 30 ng/mL may still signal deficiency in those with symptoms or higher iron needs (e.g., menstruating women, athletes, pregnancy).

Ferritin is equally important on the higher end. Although high ferritin can signal iron overload (excess iron stored in tissues), this is only one possible cause. Ferritin also increases when the body is under stress from inflammation, infection, metabolic dysfunction, or liver disease. This is because ferritin doubles as an immune-regulated protein: inflammatory cytokines stimulate ferritin production to keep iron away from pathogens, causing serum ferritin to rise even when actual iron stores are normal or low. Thus, an elevated ferritin level should always be considered alongside CRP, ESR, liver enzymes, and transferrin saturation.

High ferritin associated with metabolic stress — such as fatty liver, excess alcohol intake, obesity, or insulin resistance — reflects oxidative stress and chronic inflammation. Persistently high ferritin (>300ng/mL in adults) may be linked with increased risk of cardiovascular disease, type 2 diabetes, and liver injury. In contrast, when ferritin is within an optimal range, energy production, cognition, thyroid function, hormonal balance, and aerobic capacity all operate more smoothly.

• Below (medical attention needed): <15 ng/mL 

• Below: Male: <30; Female: 15-45 ng/mL 

• Optimal range: Male: 50-300 ng/mL; Female: 45-150 ng/mL

• Above: 150-300 ng/mL 

• Above (medical attention needed): >300 ng/mL

Ferritin levels can change for many reasons beyond diet alone. Factors that influence ferritin include:

• Inflammation or infection: Chronic inflammation, autoimmune conditions, or acute illness can raise ferritin as part of your body’s immune response.

• Digestive health: Conditions like autoimmune gastritis, Crohn’s disease, inflammatory bowel disease, or celiac disease can reduce iron absorption.

• Gut infections: Helicobacter pylori (H. pylori) can impair iron absorption and cause low ferritin.

• Not eating enough iron-rich foods: Diets low in heme iron (found in red meat, chicken, fish) or non-heme iron (from beans, lentils, spinach, tofu) can lower ferritin over time.

• Menstrual blood loss: Heavy or prolonged periods are a common cause of low ferritin in women.

• Gastrointestinal or urinary blood loss: Hidden bleeding from the gut or urinary tract can deplete ferritin stores.

• Liver disease or iron overload: Can elevate ferritin due to excess storage or liver inflammation.

• Medications: Proton pump inhibitors (PPIs) and non-steroidal anti-inflammatory drugs (NSAIDs) can interfere with absorption or cause gut irritation and blood loss.

• Dietary supplements: Excessive iron supplementation or fortified foods can raise ferritin above optimal levels.

If your results are high

Diet:

• Focus on reducing iron-rich red meat to 1–2 servings weekly and avoid iron-fortified supplements unless medically required.

• Include polyphenol-rich foods (berries, green tea, herbs/spices) that naturally reduce iron absorption.

Lifestyle:

• Limit alcohol to support liver function.

• Prioritise anti-inflammatory habits (daily movement, adequate sleep, stress regulation).

• Support metabolic health with balanced meals rich in fibre and vegetables.

Supplements:

• Avoid iron supplements.

• Consider antioxidant support (vitamin C from food sources, mixed berries, garlic, turmeric) to reduce oxidative stress.

• Discuss any supplements with a clinician if liver markers are elevated.

Additional tests:

• Transferrin saturation

• CRP

• ESR

• liver enzymes (ALT

• AST

• GGT)

• fasting glucose/insulin

• screening for haemochromatosis (HFE genotyping) if ferritin is persistently >300 ng/mL

If your results are low

Diet:

• Aim for 2–3 servings of iron-rich foods weekly: beef, lamb, sardines, chicken thighs, eggs, lentils, tofu, pumpkin seeds, spinach.

• Pair iron-rich meals with vitamin C sources like citrus, capsicum, or tomatoes.

• Separate coffee/tea by at least 1–2 hours from meals.

Lifestyle:

• Monitor menstrual blood loss; heavy periods are a common cause of deficiency.

• Space out exercise recovery with adequate protein and iron-rich meals.

• Avoid frequent blood donation until ferritin improves.

Supplements:

• Iron supplementation may be helpful when dietary strategies are insufficient.

• Forms with better tolerability include iron bisglycinate or iron polymaltose.

• Vitamin C enhances absorption.

• Always follow clinician guidance, especially if you have digestive symptoms.

Additional tests:

• Transferrin saturation

• full blood count

• B12

• folate

• CRP

• coeliac screening

• stool occult blood if bleeding is suspected

• H. pylori testing if absorption issues persist

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5. Auerbach M, DeLoughery TG. Iron deficiency in adults: a review. JAMA. 2025;333(20):1813-1823.