Ferritin

Ferritin

Vitamins & Minerals

What is Ferritin?

Ferritin is the primary iron storage protein in the body, capable of sequestering up to 4,500 iron atoms within its hollow spherical shell. Found predominantly in the liver, spleen, and bone marrow, ferritin serves as a buffer that safely stores excess iron to prevent toxicity while maintaining reserves for times of increased demand. A small amount of ferritin is released into the bloodstream, and this serum ferritin level correlates closely with total body iron stores—making it the single best laboratory test for assessing iron status.

Serum ferritin is unique among iron markers because it reflects stored iron rather than circulating iron. Unlike serum iron (which fluctuates dramatically throughout the day), ferritin is relatively stable and is the first value to drop when iron stores become depleted—well before hemoglobin falls and anemia develops. However, ferritin is also an acute-phase reactant, meaning it rises independently of iron status during inflammation, infection, liver disease, and malignancy. This dual nature makes interpretation context-dependent: a low ferritin is always diagnostic of iron deficiency, but a normal or elevated ferritin does not always rule it out if inflammation is present.

Why It Matters

Ferritin is the gold standard for detecting iron deficiency, which affects approximately 30% of the world's population. A low ferritin (<30 ng/mL) is highly specific for depleted iron stores and can identify iron deficiency months before anemia develops—enabling early intervention. Elevated ferritin is equally important to investigate, as it may indicate iron overload (hemochromatosis), liver disease, chronic inflammation, or malignancy. Because ferritin bridges nutritional assessment and disease diagnosis, it is one of the most clinically versatile blood tests available.

Normal Reference Ranges

GroupRangeUnit
Adult Men20–250ng/mL
Adult Women (premenopausal)10–120ng/mL
Adult Women (postmenopausal)20–200ng/mL
Children (6 months–15 years)7–140ng/mL
Iron Deficiency Threshold<30ng/mL

Reference ranges may vary by laboratory. Always compare results to the ranges provided by your testing facility.

What High Ferritin Levels Mean

Common Causes

  • Hereditary hemochromatosis
  • Chronic liver disease (hepatitis, cirrhosis, fatty liver)
  • Chronic inflammation or infection (ferritin as acute-phase reactant)
  • Hemolytic anemias
  • Multiple blood transfusions
  • Metabolic syndrome and obesity
  • Excessive alcohol consumption
  • Malignancy (lymphoma, leukemia, renal cell carcinoma)
  • Still's disease (adult-onset, markedly elevated ferritin)
  • Hemophagocytic lymphohistiocytosis (HLH—very high ferritin >10,000)

Possible Symptoms

  • Often asymptomatic in early stages
  • Joint pain and stiffness
  • Fatigue and weakness
  • Abdominal pain (liver involvement)
  • Skin bronzing or hyperpigmentation
  • Diabetes mellitus (pancreatic iron deposition)
  • Liver dysfunction (elevated liver enzymes)
  • Heart problems (if iron overload is present)

What to do: Evaluate the clinical context to distinguish between iron overload and reactive elevation. Check transferrin saturation: >45% suggests true iron overload, warranting HFE genetic testing. If ferritin is elevated with normal transferrin saturation, investigate for liver disease (LFTs, imaging), inflammation (CRP, ESR), metabolic syndrome, or malignancy. Very high ferritin (>1,000 ng/mL) always requires investigation. Treatment of hemochromatosis involves therapeutic phlebotomy. Reactive hyperferritinemia is treated by addressing the underlying condition.

What Low Ferritin Levels Mean

Common Causes

  • Iron deficiency (the most common cause)
  • Chronic blood loss (menstruation, GI bleeding)
  • Inadequate dietary iron intake
  • Malabsorption (celiac disease, gastric bypass)
  • Increased iron requirements (pregnancy, adolescent growth)
  • Frequent blood donation
  • Hypothyroidism (may reduce ferritin)

Possible Symptoms

  • Fatigue that is disproportionate to anemia
  • Hair loss (telogen effluvium)
  • Restless legs syndrome
  • Poor concentration and cognitive fog
  • Exercise intolerance
  • Pica (unusual cravings for ice, dirt, starch)
  • Pale skin, brittle nails
  • May occur without anemia (iron depletion without anemia)

What to do: Low ferritin confirms iron deficiency. Identify and treat the underlying cause. Premenopausal women should be asked about heavy periods. In men and postmenopausal women, GI evaluation (endoscopy/colonoscopy) is recommended to rule out occult blood loss. Oral iron (ferrous sulfate 325 mg daily or every other day) is first-line. Every-other-day dosing may actually improve absorption by reducing hepcidin surge. IV iron is indicated if oral iron fails, is not tolerated, or rapid repletion is needed. Target ferritin >50–100 ng/mL for symptom resolution. Recheck in 6–8 weeks.

When Is Ferritin Testing Recommended?

  • Evaluation of suspected iron deficiency or anemia
  • Monitoring iron supplementation therapy
  • Screening for hemochromatosis in at-risk individuals
  • Unexplained fatigue, hair loss, or restless legs
  • During pregnancy (routine screening)
  • Before and after blood donation or bariatric surgery
  • When CRP is also elevated (to help interpret ferritin in inflammatory states)

Frequently Asked Questions

While laboratory reference ranges often list lower limits of 10–20 ng/mL as "normal," many experts argue these cutoffs are too low for optimal function. Iron deficiency symptoms (fatigue, hair loss, restless legs, brain fog) frequently occur at ferritin levels of 20–50 ng/mL, well within the "normal" range. Most hematologists consider ferritin <30 ng/mL diagnostic of iron deficiency, and many clinicians aim for ferritin >50–100 ng/mL for symptom resolution. If your ferritin is 15 and the lab says "normal" but you are exhausted, iron supplementation is likely warranted.
Yes—this is a clinically important scenario. Since ferritin is an acute-phase reactant, inflammation (from infection, autoimmune disease, obesity, or even vigorous exercise) can elevate ferritin independently of iron stores. A person can be iron deficient with a "normal" ferritin if they have concurrent inflammation. In this situation, check CRP or ESR alongside ferritin. If CRP is elevated, a ferritin below 100 ng/mL in the presence of inflammation may still indicate iron deficiency. Transferrin saturation and soluble transferrin receptor (sTfR) can provide additional clarity.
This depends on the severity of depletion and the route of supplementation. With oral iron supplementation (65 mg elemental iron daily or every other day), ferritin typically begins to rise after 2–4 weeks, with meaningful improvement by 6–8 weeks. Full repletion of iron stores (ferritin >50–100 ng/mL) usually takes 3–6 months. Continuing supplementation for 3 months after hemoglobin normalizes is important to refill stores. IV iron replenishes stores much faster—often within 2–4 weeks. Recheck ferritin 6–8 weeks after starting therapy and at 3 months.
Because ferritin is an acute-phase reactant that rises with inflammation regardless of iron status. C-reactive protein (CRP) is the standard marker for systemic inflammation. By measuring both simultaneously, your doctor can determine if an elevated ferritin reflects true iron overload or is just an inflammatory response. The WHO recommends using a ferritin threshold of <30 ng/mL (instead of <15) when inflammation is present. If CRP is elevated and ferritin is "normal" (30–100 ng/mL), iron deficiency cannot be excluded. This combination prevents missed diagnoses.

Related Biomarkers

FeSerum IronHgbHemoglobinHctHematocritRBCRed Blood CellsCRPC-Reactive Protein

Want your Ferritin levels analyzed?

Upload your lab results for an instant AI-powered breakdown of all your biomarkers.

Upload Lab Results →

Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Reference ranges may vary between laboratories. Always consult your healthcare provider for interpretation of your specific test results.

Disclaimer: SymptomGPT is not a medical diagnosis tool and does not provide medical advice. Always consult a qualified healthcare professional. If you are experiencing a medical emergency, call 911 immediately.