Ferritin
Also known as: Serum Ferritin
What Does Ferritin Measure?
Ferritin is a blood protein that stores iron and releases it in a controlled manner when the body needs it. A ferritin test measures the amount of ferritin in your blood, which directly reflects the total amount of iron stored in your body. Think of ferritin as the body's iron warehouse — when ferritin levels are low, the iron stores are depleted, and when they are high, there is an excess of stored iron.
Why Does Ferritin Matter?
Ferritin is one of the most clinically important markers for evaluating iron status and is used to diagnose conditions ranging from iron deficiency anemia to iron overload disorders like hemochromatosis. Because ferritin is also an acute-phase reactant — meaning it rises during inflammation and infection — it provides insight not only into iron metabolism but also into inflammatory states in the body. Monitoring ferritin is essential for athletes, pregnant women, individuals with chronic disease, and anyone experiencing fatigue, hair loss, or unexplained symptoms that could be related to iron imbalance.
Normal Ranges
Males
24–336 ng/mL (micrograms per liter)
Females
11–307 ng/mL (micrograms per liter); optimal functional range often cited as 50–150 ng/mL
Children
Varies by age; newborns: 25–200 ng/mL; infants (1–5 months): 50–200 ng/mL; children (6 months–15 years): 7–140 ng/mL
Causes of High Levels
- Hemochromatosis (hereditary iron overload disorder causing excess iron absorption)
- Chronic inflammation or infection (e.g., rheumatoid arthritis, lupus, inflammatory bowel disease)
- Liver disease (hepatitis, cirrhosis, or non-alcoholic fatty liver disease causing ferritin release)
- Frequent blood transfusions leading to iron accumulation in tissues
- Metabolic syndrome and obesity, which promote chronic low-grade inflammation
- Certain cancers (e.g., leukemia, lymphoma, liver cancer) which can cause markedly elevated ferritin
Causes of Low Levels
- Iron deficiency anemia, the most common nutritional deficiency worldwide
- Inadequate dietary iron intake, particularly in vegetarians and vegans who avoid heme iron sources
- Chronic blood loss from heavy menstruation, gastrointestinal bleeding, or ulcers
How to Improve Your Ferritin
Diet
- Increase heme iron intake from red meat, poultry, and seafood (oysters, clams) as heme iron is absorbed at 15–35% efficiency
- Consume vitamin C-rich foods (bell peppers, citrus, strawberries) alongside iron-rich meals to enhance non-heme iron absorption by up to 3-fold
- Include iron-fortified cereals and legumes (lentils, chickpeas, black beans) as plant-based iron sources
- Avoid drinking coffee or tea with iron-rich meals as tannins can inhibit iron absorption by up to 60–70%
- Cook in cast iron cookware, which can modestly increase the iron content of acidic foods like tomato sauce
Supplements
- Ferrous sulfate 325 mg (65 mg elemental iron) taken every other day has been shown to improve absorption versus daily dosing
- Ferrous bisglycinate (iron glycinate) 25–100 mg daily as a gentler, highly bioavailable form with fewer GI side effects
- Vitamin C (ascorbic acid) 250–500 mg taken with iron supplements to enhance absorption
- Lactoferrin supplements may help improve iron bioavailability and reduce GI side effects in sensitive individuals
- Always take iron supplements on an empty stomach or with vitamin C, and avoid taking with calcium, antacids, or dairy products
Related Biomarkers
Frequently Asked Questions
What is considered a dangerously low ferritin level?
Ferritin levels below 10–12 ng/mL are generally considered indicative of iron deficiency and depleted iron stores. However, many functional medicine practitioners consider levels below 30 ng/mL as suboptimal, especially in people experiencing symptoms like fatigue, hair loss, or brain fog. Levels below 10 ng/mL are clinically significant and often associated with iron deficiency anemia requiring treatment. If your ferritin is this low, consult your doctor to rule out an underlying cause such as chronic blood loss or malabsorption.
Can ferritin be high even when I'm not iron overloaded?
Yes, absolutely. Ferritin is an acute-phase reactant protein, meaning it rises significantly in response to inflammation, infection, liver damage, and certain cancers — even without true iron overload. This is why doctors often test transferrin saturation and serum iron alongside ferritin. If your ferritin is elevated but your transferrin saturation is normal or low, inflammation is a more likely cause than iron overload. Your doctor may order additional tests like CRP or liver enzymes to determine the underlying cause.
How long does it take for ferritin levels to increase with iron supplementation?
Ferritin levels typically begin to rise within 4–8 weeks of consistent iron supplementation, but it can take 3–6 months or longer to fully replenish iron stores depending on how depleted they were, the dose of iron used, and whether the underlying cause of deficiency has been addressed. Hemoglobin levels tend to improve faster (often within 4–6 weeks) than ferritin, since the body prioritizes making red blood cells before replenishing stores. Regular monitoring every 3 months is recommended during treatment.