Lab Reference Library / Ferritin Longevity & Aging

Ferritin

FER

Reference range, optimal functional medicine levels, and why ferritin is simultaneously the body's primary iron storage protein and one of the most misinterpreted markers on a standard lab report.

Most SearchedLongevity Marker

Standard Range (W)12 to 150 ng/mL

FM Optimal (W)50 to 100 ng/mL

FM Optimal (M)70 to 150 ng/mL

Unitsng/mL

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Category: Longevity & Aging | Also known as: Serum Ferritin, Iron Storage Protein | Sample: Serum (fasting preferred)

1. What This Test Measures

Ferritin is the body's primary iron storage protein, a large spherical protein shell that stores and releases iron as needed by cells throughout the body. Serum ferritin measures the concentration of this protein circulating in the bloodstream, and serves as the most reliable proxy for total body iron stores available on a routine blood test.

Every cell in the body requires iron for fundamental functions: mitochondrial energy production via the electron transport chain, oxygen transport in red blood cells, DNA synthesis, thyroid hormone metabolism, and neurotransmitter production. When iron stores fall, these processes are progressively impaired, often producing significant symptoms well before hemoglobin drops low enough to qualify as anemia on a conventional lab report.

Ferritin has a critical dual clinical role that makes it uniquely complex to interpret:

When low: ferritin directly reflects depleted iron stores, a state of functional iron deficiency even when serum iron or hemoglobin may still appear normal.
When high: ferritin can reflect either true iron overload OR an acute-phase inflammatory response. Ferritin rises non-specifically with infection, inflammation, liver disease, metabolic syndrome, and malignancy, completely independent of iron status.

This dual nature means a high ferritin should never be interpreted at face value without concurrent evaluation of iron saturation (TSAT) and other inflammatory markers to distinguish iron excess from inflammatory elevation.

2. Why This Test Matters

Ferritin is one of the most frequently misinterpreted markers in conventional medicine, primarily because the standard lower reference limits are clinically inadequate, allowing significant iron deficiency to be missed and labeled "normal" for years.

Fatigue and energy production: iron is a critical cofactor in mitochondrial complexes I, III, and IV of the electron transport chain. Ferritin below 30 to 40 ng/mL frequently causes debilitating fatigue even with normal hemoglobin, a condition known as iron deficiency without anemia.
Hair loss: hair follicles are highly metabolically active and among the first tissues deprived when iron stores are marginal. Ferritin below 30 ng/mL is strongly associated with telogen effluvium in women. Functional medicine and dermatology literature suggests targeting ferritin above 70 to 80 ng/mL for optimal hair regrowth.
Thyroid function: iron is required for thyroid peroxidase (TPO), the enzyme that synthesizes thyroid hormones. Low ferritin directly impairs thyroid hormone production and T4-to-T3 conversion, causing hypothyroid symptoms even when TSH is normal.
Cognitive function and mood: iron is required for dopamine and serotonin synthesis. Low ferritin is associated with brain fog, depression, anxiety, and ADHD-like symptoms, particularly in women of reproductive age.
Restless legs syndrome: low ferritin is among the most common and treatable causes of restless legs syndrome, with ferritin below 50 ng/mL strongly associated with symptom severity.
Exercise performance and recovery: iron is required for oxygen delivery to working muscles. Ferritin below optimal significantly impairs VO2 max, endurance, and recovery in athletes.
Iron overload risk: elevated ferritin above 300 ng/mL in men or 200 ng/mL in women may indicate hemochromatosis, a common genetic condition affecting 1 in 200 to 300 people of Northern European descent.

3. Standard Lab Reference Range

Population	Standard Range	Units
Women (premenopausal)	12 to 150	ng/mL
Women (postmenopausal)	12 to 263	ng/mL
Men	24 to 336	ng/mL

The lower limits of these ranges, 12 ng/mL for women, are critically inadequate. A ferritin of 14 ng/mL is "normal" by conventional standards but almost universally associated with significant fatigue, hair loss, and impaired cellular function in premenopausal women. This is one of the largest gaps between "normal" and "optimal" in all of functional medicine.

4. Optimal Functional Medicine Range

Ferritin Level	Women Interpretation	Men Interpretation
50 to 100 ng/mL (W) / 70 to 150 ng/mL (M)	Optimal iron stores	Optimal iron stores
30 to 49 ng/mL (W) / 40 to 69 ng/mL (M)	Suboptimal; may explain fatigue and hair loss	Below optimal; iron repletion indicated
Below 30 ng/mL (W) / Below 40 ng/mL (M)	Iron deficiency; evaluate and treat regardless of hemoglobin	Iron deficiency; evaluate cause and treat
150 to 200 ng/mL	Elevated; rule out inflammation; check TSAT	High-normal; monitor; check TSAT if trending up
Above 200 ng/mL (W) / Above 300 ng/mL (M)	Evaluate for iron overload or significant inflammation	Evaluate for hemochromatosis; HFE gene testing, TSAT, liver function

For hair loss specifically, many dermatologists and functional medicine practitioners target ferritin above 70 to 80 ng/mL regardless of sex. For restless legs syndrome, ferritin above 50 to 75 ng/mL is the typical therapeutic target.

5. Symptoms Associated With Abnormal Levels

Low Ferritin (below 30 to 50 ng/mL)

Persistent fatigue despite adequate sleep
Hair thinning, excessive shedding, or diffuse hair loss
Brain fog and difficulty concentrating
Cold intolerance (cold hands and feet)
Restless legs syndrome, especially at night
Shortness of breath on exertion
Poor exercise tolerance and slow recovery
Brittle nails with ridges or spooning (koilonychia)
Pica (craving non-food items like ice)
Hypothyroid-like symptoms even with normal TSH
Mood disturbances: depression, anxiety, irritability

High Ferritin (above 200 to 300 ng/mL)

Often asymptomatic in early iron overload
Joint pain and stiffness, particularly knuckles and knees
Fatigue and weakness (paradoxically; iron toxicity)
Abdominal pain (liver involvement)
Skin bronzing or darkening
Reduced libido and erectile dysfunction (hormonal effects)
Diabetes symptoms (iron deposits in pancreatic beta cells)
Cardiac arrhythmias (advanced iron overload)
If inflammatory: signs of underlying condition driving elevation

6. What Causes Abnormal Results

Causes of low ferritin

Heavy menstrual bleeding: the most common cause of low ferritin in premenopausal women; monthly blood loss can exceed the body's ability to replete iron through diet alone
Inadequate dietary iron intake: vegetarian and vegan diets provide only non-heme iron, which absorbs at 2 to 10% versus 15 to 35% for heme iron from meat
Impaired iron absorption: celiac disease, Crohn's disease, H. pylori infection, achlorhydria (low stomach acid), proton pump inhibitor use
Increased iron demand: pregnancy, breastfeeding, rapid growth in adolescence
Frequent blood donation
Chronic blood loss: GI bleeding (ulcers, colon polyps, colorectal cancer), bladder bleeding
Intense endurance exercise: foot-strike hemolysis and hepcidin upregulation
Hypothyroidism: impairs iron absorption independently

Causes of high ferritin

Hereditary hemochromatosis: HFE gene mutations (C282Y homozygous) cause progressive iron accumulation; affects approximately 1 in 200 to 300 people of Northern European descent
Metabolic syndrome and NAFLD: the most common cause of moderately elevated ferritin in the general population; represents inflammatory elevation, not iron overload
Chronic inflammation: rheumatoid arthritis, inflammatory bowel disease, autoimmune disease
Liver disease: alcoholic hepatitis, viral hepatitis, cirrhosis; liver cell destruction releases intracellular ferritin
Acute infection or inflammatory illness
Malignancy: leukemia, lymphoma, certain solid tumors; ferritin is an acute-phase reactant
Excessive iron supplementation
Alcohol excess: promotes iron absorption and liver inflammation

7. How to Improve This Marker

For Low Ferritin

Increase heme iron sources: red meat (grass-fed beef, lamb), dark poultry meat, organ meats (liver is the richest source)
Pair non-heme iron foods (spinach, lentils, tofu) with vitamin C to enhance absorption
Avoid tea, coffee, and calcium-rich foods within 1 to 2 hours of iron-rich meals; they inhibit absorption
Cook in cast iron cookware; transfers small amounts of dietary iron
Address heavy menstrual bleeding with appropriate gynecological evaluation
Test and treat H. pylori or celiac disease if present
Optimize stomach acid production; consider betaine HCl if hypochlorhydric

Supplementation

Iron bisglycinate: most tolerable oral form; significantly less GI side effects than ferrous sulfate; 25 to 50mg elemental iron daily
Ferrous sulfate: standard, highly effective, lower cost; take with vitamin C; GI side effects common
Liquid iron formulations: useful when tablet absorption is problematic
IV iron infusion: for severe deficiency, malabsorption, or when oral iron is not tolerated; most rapid repletion method
Take iron on alternate days; research shows every-other-day dosing achieves similar repletion with better absorption and fewer side effects
Retest ferritin at 3 to 4 months to assess repletion progress

For High Ferritin

First step: check iron saturation (TSAT); above 45% strongly suggests true iron overload; below 45% with high ferritin suggests inflammatory elevation
Order HFE gene testing if TSAT is elevated; confirms or rules out hereditary hemochromatosis
For hemochromatosis: therapeutic phlebotomy (blood donation) is the standard treatment; removes iron and rapidly normalizes ferritin
For inflammatory elevation: identify and treat the underlying inflammatory driver
Reduce alcohol consumption; directly lowers ferritin through reduced absorption stimulation and improved liver function
IP6 (inositol hexaphosphate): natural iron chelator; used adjunctively for mild iron excess under physician supervision

8. Related Lab Tests

Ferritin is most informative when interpreted alongside these related markers:

Iron (Serum)Interpret Together with Ferritin

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Iron Saturation (TSAT)Distinguishes Overload from Inflammation

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TIBCRises with Deficiency; Falls with Overload

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hs-CRPConfirms Inflammatory Ferritin Elevation

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TSHLow Ferritin Impairs TPO Enzyme

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Vitamin B12Commonly Co-deficient with Iron

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9. When Testing Is Recommended

Any woman with fatigue, hair loss, brain fog, or poor exercise tolerance regardless of hemoglobin level
Premenopausal women with heavy menstrual periods
Vegetarians and vegans; significantly increased risk of iron deficiency
Athletes, particularly female endurance athletes (high demand and foot-strike hemolysis)
Restless legs syndrome; ferritin evaluation is a standard first step
Individuals with GI symptoms or known malabsorption: celiac, Crohn's, GERD on PPIs
Family history of hemochromatosis; screen with ferritin and TSAT
Unexplained liver enzyme elevation; ferritin is part of a complete liver assessment
Annual monitoring in all patients with known iron deficiency until ferritin reaches optimal range
Patients with metabolic syndrome and elevated ferritin to distinguish inflammatory from iron-overload etiology

10. Clinical Perspective

Clinical Perspective

Ferritin is the lab result I probably have the most conversations about. A woman comes in exhausted, losing hair by the handful, told repeatedly her labs are "normal," and her ferritin is 16. That is "normal" on a conventional report. From a functional medicine standpoint, it is iron deficiency, full stop. The conventional lower limit of 12 ng/mL was derived from population averages in people who were already symptomatic with anemia. It tells us nothing about optimal cellular function. We target 50 to 100 ng/mL for women, and above 75 when hair loss is the primary complaint. The transformation when ferritin reaches optimal is often dramatic: energy returns, hair shedding slows, brain fog lifts. It is one of the most gratifying clinical turnarounds we see, and one of the most preventable conditions we encounter, because it was labeled "normal" for years before anyone looked critically at the number.

Brian Lamkin, DO | Founder, The Lamkin Clinic | Edmond, Oklahoma

11. Frequently Asked Questions

What is the optimal ferritin level for women?

In functional medicine, the optimal ferritin level for women is 50 to 100 ng/mL. The standard lower limit of 12 ng/mL is clinically inadequate; ferritin below 30 ng/mL is almost universally associated with symptoms including fatigue, hair loss, brain fog, and poor exercise tolerance in premenopausal women, even when hemoglobin remains normal. For hair loss specifically, most functional medicine practitioners and dermatologists target above 70 to 80 ng/mL.

What does low ferritin cause?

Low ferritin causes fatigue and low energy, hair thinning and excessive shedding (telogen effluvium), brain fog, cold intolerance, restless legs syndrome, poor exercise tolerance, brittle nails, and mood disturbances including depression and anxiety. These symptoms often appear at ferritin levels of 20 to 40 ng/mL in women, well above the conventional anemia threshold, because iron is required for mitochondrial energy production, thyroid hormone metabolism, and neurotransmitter synthesis.

Can low ferritin cause hair loss?

Yes. Low ferritin is one of the most common and reversible causes of hair loss in women. Hair follicles are highly metabolically active and among the first tissues deprived when iron stores are marginal. Research published in the Journal of the American Academy of Dermatology established ferritin below 30 ng/mL as associated with telogen effluvium. Most functional medicine practitioners now target ferritin above 70 to 80 ng/mL for optimal hair growth response.

What does high ferritin mean?

Elevated ferritin can reflect either iron overload (as in hereditary hemochromatosis) or an acute-phase inflammatory response. Because ferritin rises non-specifically with inflammation, metabolic syndrome, liver disease, infection, and certain cancers independent of iron status, an elevated ferritin must always be interpreted alongside iron saturation (TSAT). TSAT above 45% suggests true iron overload; below 45% with high ferritin typically indicates inflammatory elevation.

What ferritin level causes fatigue?

Fatigue from low ferritin can occur at levels well above the conventional anemia threshold. Many women experience significant fatigue with ferritin below 30 to 40 ng/mL even with normal hemoglobin. This is because iron is required for mitochondrial energy production, not just oxygen transport. The conventional lower limit of 12 ng/mL is far too low to support optimal cellular energy function.

What is the optimal ferritin level for men?

In functional medicine, optimal ferritin for men is generally 70 to 150 ng/mL. Values above 200 ng/mL in men warrant evaluation for hereditary hemochromatosis (HFE gene testing and iron saturation) or significant inflammatory burden. Men are less likely to develop iron deficiency than premenopausal women, but are more likely to develop undetected iron overload.

Content authored and clinically reviewed by Brian Lamkin, DO, founder of The Lamkin Clinic in Edmond, Oklahoma. Brian Lamkin, DO has 25+ years of experience in functional and regenerative medicine. This page reflects current functional medicine practice standards and is updated as new clinical evidence becomes available.

Stop accepting normal. Start targeting optimal.

A ferritin of 14 is not fine if you are exhausted and losing hair. Schedule a consultation to review your iron status and build a repletion plan based on your specific level and clinical picture.

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Medical Disclaimer: This content is provided for educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Lab interpretation should always be performed in clinical context by a qualified healthcare provider. Reference ranges and optimal targets may vary based on individual patient history, clinical presentation, and laboratory methodology. Schedule a consultation to discuss your specific results with Dr. Lamkin.