What is the definition of Iron Deficiency (ID) Anemia?

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From the Guidelines

Iron deficiency should be confirmed by iron studies, with serum ferritin being the single most useful marker, prior to investigation, as recommended by the British Society of Gastroenterology guidelines 1.

Definition of Iron Deficiency

Iron deficiency is defined by low serum ferritin levels, and other laboratory markers such as decreased transferrin saturation, increased total iron-binding capacity, and low serum iron levels can also be helpful in diagnosis.

  • A good response to iron therapy, with a hemoglobin rise of ≥10 g/L within a 2-week timeframe, is highly suggestive of absolute iron deficiency, even if the results of iron studies are equivocal 1.
  • Anaemia is defined as a haemoglobin concentration below the lower limit of normal for the relevant population and laboratory performing the test 1.

Diagnosis and Stages

Iron deficiency progresses through stages, beginning with depleted iron stores, followed by iron-deficient erythropoiesis, and finally iron deficiency anemia.

  • Common causes of iron deficiency include inadequate dietary intake, blood loss, malabsorption disorders, and increased iron requirements during pregnancy or growth periods.
  • Symptoms of iron deficiency may include fatigue, weakness, pale skin, brittle nails, headaches, dizziness, and in severe cases, pica and restless leg syndrome.

Treatment and Prevention

Early identification and treatment with iron supplementation can prevent progression to more severe deficiency states, and a good response to iron therapy can confirm the diagnosis of iron deficiency 1.

From the Research

Definition of Iron Deficiency

Iron deficiency is defined as a state where the body's iron stores are depleted, which can lead to iron-deficiency anemia if left untreated 2. Iron-deficiency anemia is characterized by low hemoglobin levels due to insufficient iron stores 2, 3.

Diagnosis of Iron Deficiency

The diagnosis of iron deficiency is typically made by measuring serum ferritin levels, with a cut-off value of <30 ng/mL indicating iron deficiency in individuals without inflammatory conditions 2, 4. Transferrin saturation (iron/total iron binding capacity × 100) less than 20% can also be used to diagnose iron deficiency 2.

Key Factors in Iron Deficiency

Some key factors to consider when evaluating iron deficiency include:

  • Serum ferritin levels: a key indicator of iron stores 2, 4
  • Transferrin saturation: helps to assess iron availability 2
  • Inflammatory conditions: can affect iron metabolism and diagnosis 2, 4, 5
  • Dietary iron intake: inadequate intake can contribute to iron deficiency 2

Types of Iron Deficiency

There are different types of iron deficiency, including:

  • Absolute iron deficiency: characterized by low iron stores with or without anemia 2, 5
  • Relative iron deficiency: occurs when there is a lack of iron in specific organs or tissues, often in the context of inflammatory disorders 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Iron deficiency anemia.

American family physician, 2007

Research

[Iron deficiency anaemia--interpretation of biochemical and haematological findings].

Tidsskrift for den Norske laegeforening : tidsskrift for praktisk medicin, ny raekke, 2013

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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