Iron is essential for numerous bodily functions, from carrying oxygen in our blood to supporting energy production. However, too little and too much iron can lead to health problems.

That is why practitioners use Ferritin levels to measure iron in patients, as Ferritin is a primary biomarker of total-body iron status. Healthcare professionals must be able to interpret ferritin levels accurately to diagnose and manage various conditions. This article will provide a detailed guide to interpreting ferritin lab results, empowering healthcare professionals with the knowledge they need to deliver optimal healthcare.

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What Is Ferritin?

Ferritin is a protein that stores iron and releases it in a controlled manner when needed. Think of ferritin as your body's savings account for iron. Just like you put money into a savings account for future use, your body stores iron in ferritin for times when it's needed.

When you consume iron-rich foods or supplements, your body absorbs the iron into the bloodstream. Excess iron is stored in ferritin molecules within cells, primarily in the liver, spleen, and bone marrow. (14) 

Because ferritin concentrations reflect the amount of iron stored in the body's tissues, it is an important marker for diagnosing iron metabolism disorders. (13) 

Ferritin Reference Ranges Based on Age & Gender

The ranges listed below are standard intervals for ferritin; however, normal ranges may vary among different laboratories. This is because reference ranges are established by analyzing samples from a population representative of the population being tested. (1) 

Reference ranges for ferritin can vary depending on the population being evaluated. Factors that can influence reference ranges include health status, age, gender, diet, and geographic location. Therefore, these factors should be considered to assess whether ferritin levels are within an appropriate range for a specific person. (1) 

High Ferritin Levels: Causes and Implications

High ferritin may be caused by iron overload, secondary to excessive dietary or supplemental iron consumption, frequent blood transfusions, or hemochromatosis (a genetic disorder characterized by excessive iron absorption). Excess iron will deposit in tissues, leading to organ damage and dysfunction. Ferritin levels exceeding 300 ng/mL in men or 150-200 ng/mL in menstruating women raise suspicion of iron overload. 

However, ferritin is also a positive acute-phase reactant (APR). A positive APR is a marker that increases in response to inflammation, infection, cancer, and tissue injury. When the body fights cancer or infection, ferritin stores extra iron to keep it away from tumor cells or harmful microbes that need it to grow. Inflammatory conditions that can cause elevated ferritin levels include: 

• Adult-onset Still's disease
• Alcohol use disorder
• Autoimmune disease
• Cancer
• Diabetes
• Hyperthyroidism
• Kidney disease
• Liver disease
• Obesity

Low Ferritin Levels: Causes and Implications

Low ferritin is indicative of iron deficiency. Common causes include inadequate dietary iron intake, chronic blood loss from gastrointestinal bleeding or heavy menstrual periods, and malabsorption syndromes.

Iron is required to make hemoglobin, the protein in red blood cells that carries oxygen to tissues. Without enough iron, the body cannot produce adequate hemoglobin, causing iron deficiency anemia. If left untreated, iron deficiency anemia can lead to chronic fatigue, restless legs syndrome (RLS), heart problems, pregnancy complications, and developmental delays in children. (7) 

Ferritin levels under 30 ng/mL in adults warrant treatment for iron deficiency. Guidelines recommend using oral iron as initial therapy to treat iron deficiency. Patients who do not adequately respond to or cannot tolerate oral iron should be referred for intravenous (IV) iron therapy. Red blood cell transfusion is generally recommended for patients with iron deficiency anemia when hemoglobin levels are less than 7 g/dL. The severity of the patient's clinical condition and symptoms will help determine whether IV iron and/or blood transfusions should be initiated sooner. (29) 

Interpreting Ferritin Levels in Context

Additional labs that are commonly ordered with ferritin to fully understand iron status and the underlying cause of abnormal levels include:

• Serum iron measures the amount of iron circulating in the blood. Low serum iron levels indicate iron deficiency, while high levels suggest iron overload.
• Total iron binding capacity (TIBC) measures the blood's capacity to bind and transport iron. Elevated TIBC levels are often seen in iron deficiency anemia, as the body tries to increase its capacity to transport iron.
• Transferrin saturation (TSAT) reflects the percentage of transferrin (a protein that transports iron) saturated with iron. Low TSAT values indicate iron deficiency, while higher than 45% suggest iron overload.
• A complete blood count (CBC) includes measurements of red blood cell indices such as hemoglobin, hematocrit, mean corpuscular volume (MCV), and red blood cell distribution width (RDW). Abnormalities in these parameters can provide additional clues about the presence and severity of anemia.
• Inflammatory Markers: Ordering markers such as C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) can determine whether elevated ferritin is secondary to inflammation.

Interpreting ferritin levels should be approached on a case-by-case basis, considering the patient's overall clinical picture, medical history, symptoms, and risk factors. While specific reference ranges exist for ferritin, they may not always accurately reflect an individual's iron status or health condition. Age, gender, ethnicity, and underlying health conditions can influence ferritin levels, so results should be contextualized within the broader clinical picture.

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Practical Steps for Healthcare Providers

Ordering a ferritin test is an important aspect of assessing iron status. Here are general guidelines for integrating this test into clinical practice:

When to Test Ferritin

Doctors should order a ferritin test when patients present with signs and symptoms of abnormal iron levels.

Symptoms of Low Iron:

• Pale skin
• Fatigue
• Weakness
• Dizziness
• Shortness of breath
• Rapid heart rate 
• Headache
• Cold hands and feet
• Hair loss
• Cravings for non-food items, such as dirt

Symptoms of Iron Overload:

• Chronic fatigue
• Joint pain
• Abdominal pain
• Irregular heart rhythm 
• Decreased sex drive
• Elevated blood sugar 
• Bronze skin
• Depression

Ferritin can also be used as a screening test for asymptomatic patients at high risk for disorders of iron metabolism. 

Populations At Risk for Iron Deficiency:

• Infants, children, and adolescents
• People who are pregnant
• People who menstruate
• People with gastrointestinal disorders
• Vegetarians and vegans

Risk Factors for Hemochromatosis

• Having two copies of an altered HFE gene
• Family history of hemochromatosis
• Northern European descent
• Male sex

Populations At Risk for Iron Overload

• Men and postmenopausal women taking iron supplements
• People requiring frequent blood transfusions

Next Steps

After receiving an abnormal ferritin level, doctors should order additional tests to understand the cause.

Follow-up testing and evaluation for low ferritin levels should include:

• Patient history: screen for pregnancy, low-iron diet, heavy menstrual cycles, gastrointestinal symptoms, frequent blood donation
• Labs: iron panel, CBC
• Referral to specialists as neededsome text
  • Gynecologist for abnormal uterine bleeding
  • Gastroenterologist for evaluation of malabsorption syndromes or gastrointestinal bleeding

Follow-up testing and evaluation for high ferritin levels should include: 

• Patient history: presence of chronic disease or infection, alcohol intake, use of iron supplements, family history of hemochromatosis
• Labs: iron panel, CBC, CRP, ESR, comprehensive metabolic panel (CMP), HFE gene testing, anti-nuclear antibodies (ANA)  
• Referrals should be guided by patient history and lab results to treat the underlying cause of elevated ferritin. Possible referral options include:some text
  • Endocrinologist 
  • Hematologist
  • Hepatologist
  • Oncologist
  • Rheumatologist

Patient Education

Effectively communicating the significance of ferritin lab results to patients ensures they understand their results and the implications for their health. Here are some tips to facilitate clear and meaningful communication:

• Avoid medical jargon and use simple, easy-to-understand language 
• Provide context: help patients understand normal ferritin levels and how their results compare. 
• Explain the symptoms and potential risks associated with abnormal ferritin levels. For example, low ferritin levels may lead to symptoms of fatigue, weakness, and shortness of breath, while high levels could indicate iron overload or inflammation.
• Discuss the possible reasons why ferritin levels may be abnormal.
• Stress the importance of follow-up appointments and further testing to determine the underlying cause of abnormal ferritin levels and develop an appropriate treatment plan. 

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Key Takeaways

• Ferritin is a protein that stores iron in the body and is a marker for iron status.
• High ferritin levels can indicate conditions such as iron overload, inflammation, infection, or other chronic diseases. 
• Low ferritin levels signify iron deficiency due to insufficient dietary intake, reduced gastrointestinal absorption, or chronic blood loss.
• Ordering a ferritin test as part of holistic healthcare allows for a comprehensive assessment of iron status and early detection of underlying health conditions. The next steps for follow-up on abnormal ferritin levels may include additional testing to determine the underlying cause, such as serum iron, transferrin saturation, or genetic testing.
• Treatment and management strategies can then be tailored to address the patient's specific needs, promoting better health outcomes.