Surreal illustration of a blood drop transforming into an iron fortress, symbolizing ferritin's role in health.

Decoding Your Blood Test: Ferritin and Iron Levels Explained

Jordan Keane in Health & Wellness December 2025 • 4 min read.

"Understand what serum ferritin and transferrin saturation (TSAT) levels mean for your health, especially for children and teens."

Ferritin is a crucial protein that stores iron and releases it when your body needs it. It's essential for regulating iron levels and reflects the body's iron stores and any systemic inflammation. While ferritin is found in most tissues, a small amount circulates in the serum, acting as an iron carrier.

Serum ferritin (SF) acts as a safe storage for iron and transports it where needed. Free iron can be toxic, catalyzing the formation of harmful free radicals. Measuring ferritin levels, along with serum iron and total iron-binding capacity (TIBC), helps diagnose iron deficiency anemia.

Transferrin saturation (TSAT) indicates how much serum iron is bound to transferrin, the protein that carries iron in the blood. While ferritin levels usually correlate with the total iron stored, chronic diseases can falsely elevate ferritin as an inflammatory response, not necessarily indicating iron overload. Understanding these nuances is crucial for accurate health assessments.

What's Considered Normal? Key Reference Values

Surreal illustration of a blood drop transforming into an iron fortress, symbolizing ferritin's role in health.

A recent study aimed to establish reference values for serum ferritin (SF) and transferrin saturation (TSAT) in Korean children and adolescents. Researchers analyzed data from 2,487 participants (1,311 males and 1,176 females) aged 10-20 years, using data from the Korea National Health and Nutrition Examination Survey (2010–2012). They calculated age- and gender-specific means and percentile values for SF and TSAT.

The study revealed significant gender differences in ferritin levels starting around age 14. In males, mean SF levels tended to remain steady between ages 10 and 14, increasing thereafter. In females, SF levels decreased until age 15 and then remained constant. High SF levels were associated with obesity, while lower levels were associated with anemia and the onset of menstruation (menarche).

Here's a breakdown of what these findings mean:

Age Matters: Reference values for SF and TSAT vary significantly with age, particularly during puberty.
Gender Plays a Role: After age 14, males tend to have higher ferritin levels than females.
Health Conditions Impact Levels: Obesity, anemia, and menarche can all influence SF levels.

These established reference values for SF and TSAT can help healthcare professionals in Korea assess the relationship between SF values and various diseases in children and adolescents. Understanding these normal ranges is critical for diagnosing and managing iron-related health issues.

The Big Picture: Why This Matters for You

Understanding ferritin and TSAT levels is more than just knowing numbers; it's about understanding your body's iron health. These values provide insights into iron storage, potential inflammation, and even risks of certain diseases.

If you're concerned about your iron levels or have received blood test results you don't understand, discuss them with your doctor. They can interpret your results in the context of your individual health and risk factors.

This research highlights the importance of age- and gender-specific reference values, especially for children and adolescents. By establishing these standards, healthcare providers can better assess iron health and potentially prevent or manage related health issues.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.5045/br.2018.53.1.18, Alternate LINK

Title: Reference Values For Serum Ferritin And Percentage Of Transferrin Saturation In Korean Children And Adolescents

Subject: Hematology

Journal: Blood Research

Publisher: The Korean Society of Hematology

Authors: Hea Lin Oh, Jun Ah Lee, Dong Ho Kim, Jung Sub Lim

Published: 2018-01-01

Everything You Need To Know

What is serum ferritin and why is it important?

Serum ferritin (SF) is a protein that stores iron and releases it when your body needs it. It's crucial for regulating iron levels. It reflects the body's iron stores and any systemic inflammation. Measuring serum ferritin levels helps in diagnosing iron deficiency anemia. Free iron can be toxic, catalyzing the formation of harmful free radicals.

What does transferrin saturation (TSAT) tell you about iron in your blood?

Transferrin saturation (TSAT) indicates how much serum iron is bound to transferrin, the protein that carries iron in the blood. TSAT is an important measurement because it shows the availability of iron for delivery to cells throughout the body. Understanding TSAT in conjunction with ferritin levels provides a comprehensive view of iron metabolism. Discrepancies between ferritin and TSAT can point to conditions beyond simple iron deficiency, such as chronic diseases affecting iron utilization.

What are considered normal serum ferritin (SF) and transferrin saturation (TSAT) levels in children and teens?

According to a recent study on Korean children and adolescents, normal serum ferritin (SF) and transferrin saturation (TSAT) levels vary significantly with age and gender, especially after age 14. Males tend to have higher ferritin levels than females after this age. Additionally, health conditions like obesity, anemia, and the onset of menstruation (menarche) can influence SF levels. This highlights the importance of considering age, gender, and health status when interpreting SF and TSAT levels.

Can chronic diseases affect serum ferritin levels, and how does this impact understanding iron levels?

While serum ferritin (SF) levels usually correlate with the total iron stored in the body, chronic diseases can falsely elevate ferritin levels as an inflammatory response. This means that high ferritin levels may not always indicate iron overload; they could be a sign of underlying inflammation. To get an accurate assessment, it's essential to consider other factors and tests beyond just ferritin levels, such as transferrin saturation (TSAT) and markers of inflammation.

Why is it important to understand serum ferritin (SF) and transferrin saturation (TSAT) levels?

Understanding serum ferritin (SF) and transferrin saturation (TSAT) levels is vital because these values provide insights into your body's iron health, potential inflammation, and even risks of certain diseases. For example, consistently low ferritin levels may indicate iron deficiency anemia, while elevated levels, in the absence of iron overload, might point to chronic inflammation. By monitoring and interpreting these levels, healthcare professionals can better diagnose and manage iron-related health issues, especially in vulnerable populations like children and adolescents.