Ferritin
Ferritin is a protein that stores iron inside cells and releases it when needed. Blood ferritin levels reflect total body iron stores and are the most sensitive and specific test for iron deficiency. Low ferritin is the earliest indicator of depleting iron reserves, often dropping before hemoglobin or other red blood cell markers change.
Ferritin is also an acute-phase reactant, meaning it can be elevated during inflammation, infection, or liver disease — even when iron stores are actually low. For this reason, ferritin should be interpreted alongside other markers like hsCRP, transferrin saturation, and serum iron.
Both low and high ferritin levels are clinically significant. Low ferritin causes fatigue, hair loss, poor exercise tolerance, and restless legs. Very high ferritin (>500 ng/mL) may indicate iron overload (hemochromatosis), chronic inflammation, or liver disease.
What It Measures
Ferritin measures the amount of stored iron in the body. Each ferritin molecule can hold up to 4,500 iron atoms. Blood ferritin levels correlate with total body iron reserves.
Reference Ranges
| Status | Range (ng/mL) |
|---|---|
| Optimal | 50–150 ng/mL (women), 75–200 ng/mL (men) |
| Normal | 20–200 ng/mL (women), 30–300 ng/mL (men) |
| Borderline | 12–20 ng/mL |
| Out of Range | < 12 ng/mL or > 500 ng/mL |
Optimal Ranges
| Group | Range | Unit | Source |
|---|---|---|---|
| Adult Men | 30–300 | ng/mL | Standard reference |
| Adult Women (pre-menopausal) | 20–200 | ng/mL | Standard reference |
| Optimal (functional) | 50–150 | ng/mL | Functional range |
When Values Are High
May indicate iron overload (hemochromatosis), chronic inflammation, liver disease, or metabolic syndrome. Elevated ferritin with normal iron saturation often points to inflammation rather than true iron excess.
When Values Are Low
Iron deficiency — the most common nutritional deficiency worldwide. Symptoms include fatigue, hair loss, brain fog, exercise intolerance, and restless legs. Can precede anemia by months.
What To Do
Lifestyle
- •Pair iron-rich foods with vitamin C for absorption
- •Avoid tea/coffee within 1 hour of iron-rich meals
- •Regular exercise helps regulate iron metabolism
Supplements
- •Iron bisglycinate if deficient (better absorbed, fewer GI side effects)
- •Avoid supplementing without confirmed deficiency — excess iron is harmful
- •Lactoferrin may improve absorption when standard supplements cause GI issues
When to Retest
Retest 8–12 weeks after starting supplementation
How GATOR Tracks This
Lab Providers
Related Biomarkers
This content is for informational purposes only and does not constitute medical advice. Reference ranges may vary by laboratory and individual factors. Consult a qualified healthcare provider for interpretation of your results and treatment decisions.
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