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Iron Studies

Understanding Your Ferritin Levels

Ferritin is the best indicator of your body's iron stores. Learn what your level means and how to optimize it.

What is Ferritin?

Ferritin is a protein that stores iron inside your cells. Think of it as your body's iron savings account — when you need iron, your body withdraws from these reserves.

Your blood ferritin level reflects how much iron you have stored throughout your body. Unlike serum iron (which fluctuates throughout the day), ferritin gives you the big picture of your iron status.

According to the World Health Organization, each 1 ng/mL of ferritin represents approximately 8-10 mg of stored iron. So a ferritin of 100 ng/mL means you have roughly 800-1000 mg of iron in reserve.

Why it matters: Iron is essential for making hemoglobin (which carries oxygen), producing energy, supporting immune function, and synthesizing neurotransmitters. When ferritin drops, all these processes suffer.
50-150 ng/mLOptimal

Healthy iron stores with good reserves

30-50 ng/mLLow Normal

Adequate but suboptimal, consider optimization

15-30 ng/mLLow (Iron Deficiency)

Depleted stores, likely causing symptoms

Below 15 ng/mLSeverely Low

Near-exhausted stores, treatment needed

What Does Your Ferritin Mean?

Select your ferritin value for a detailed explanation of what it means and what to do next.

10
ng/mL
Severely low
20
ng/mL
Low
30
ng/mL
Borderline

Ferritin vs. Other Iron Tests

Your doctor may order several iron-related tests. Here's how they differ:

TestWhat It Measures
FerritinIron stored in your body (best overall indicator)
Serum IronIron circulating in blood right now (fluctuates daily)
TIBCBlood's capacity to carry iron (high when stores are low)
Transferrin Saturation% of iron-carrying capacity being used (<20% = deficiency)
HemoglobinOxygen-carrying protein (drops last, after stores depleted)
Key insight: Ferritin drops first as iron stores deplete. You can have symptoms of iron deficiency with normal hemoglobin — this is called "iron deficiency without anemia." According to recent research, this condition is underdiagnosed and undertreated.

Symptoms of Low Ferritin

Iron is essential for oxygen transport and energy production. When ferritin is low, these processes suffer:

Fatigue & Weakness
Persistent tiredness that doesn't improve with rest
Shortness of Breath
Getting winded with mild exertion
Dizziness
Lightheadedness, especially when standing
Restless Leg Syndrome
Uncomfortable urge to move legs, especially at night
Hair Loss
Diffuse thinning, not patterned baldness
Brain Fog
Difficulty concentrating, poor memory
Brittle Nails
Spoon-shaped (koilonychia) or easily broken
Pica
Craving ice, dirt, starch, or other non-food items

Common Causes of Low Ferritin

Blood Loss

Heavy menstrual periods, GI bleeding (ulcers, polyps, hemorrhoids), frequent blood donation. In men and postmenopausal women, GI bleeding should always be ruled out.

Inadequate Intake

Vegetarian/vegan diets (plant iron is poorly absorbed), restrictive eating, poor overall nutrition. Daily requirement: 8mg (men), 18mg (premenopausal women).

Absorption Problems

Celiac disease, inflammatory bowel disease, gastric bypass surgery, chronic PPI/antacid use, H. pylori infection. Iron is absorbed in the duodenum.

Increased Needs

Pregnancy (blood volume increases 50%), breastfeeding, adolescent growth spurts, endurance athletics (foot-strike hemolysis, sweat losses).

How to Raise Ferritin Levels

Iron supplements
Ferrous sulfate 325mg (65mg elemental iron) daily. Take on empty stomach with vitamin C. Expect ferritin to rise 15-30 ng/mL per month.
Heme iron foods
Red meat, liver, oysters, sardines — heme iron is absorbed at 15-35% vs. 2-20% for plant iron.
Vitamin C pairing
Taking iron with vitamin C (orange juice, 250mg supplement) can increase absorption by 2-3x, especially for plant sources.
Avoid absorption blockers
Don't take iron with coffee, tea, calcium, or antacids — they reduce absorption significantly.
IV iron if needed
For malabsorption, intolerance to oral iron, or need for rapid repletion. Works within 2-4 weeks.
Important: Continue iron treatment until ferritin reaches 50-100 ng/mL, not just until you feel better. Stopping too early leads to recurrence.

When Ferritin Is Too High

While this page focuses on low ferritin, elevated ferritin (>300 ng/mL in men, >200 ng/mL in women) also warrants attention:

  • Inflammation: Ferritin is an acute phase reactant — it rises with infection, chronic disease, and inflammation (even if iron stores are normal or low)
  • Hemochromatosis: Genetic iron overload disorder causing ferritin >500-1000+ ng/mL
  • Liver disease: Damaged liver cells release ferritin into blood
  • Over-supplementation: Taking iron when not needed

High ferritin with inflammation can mask concurrent iron deficiency. In these cases, transferrin saturation helps clarify true iron status.

Track Your Ferritin Over Time

Upload your lab reports and see your ferritin trend. Know if your iron treatment is working.

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Related

Hemoglobin 10 g/dLVitamin B12 GuideAnemia Lab TrackerAnemia Biomarker Guide

Ferritin Questions

References

  1. WHO. Use of ferritin concentrations to assess iron status. 2020
  2. ASH. Draft Recommendations for Diagnosis of Iron Deficiency. 2025
  3. AAFP. Iron Deficiency Anemia: Evaluation and Management. 2013
  4. Iron deficiency without anaemia: a diagnosis that matters. PMC. 2021