Anemia - Iron-Deficiency Disease Summary

Last updated: 13 February 2026
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Overview

Anemia is a condition wherein the blood has low levels of red blood cells (RBC), hemoglobin (oxygen-carrying pigment in whole blood) or hematocrit (intact RBC in the blood) making it insufficient to address the physiological needs of the body as defined in the Introduction section. This section also states the World Health Organization (WHO) definition of anemia. Iron-deficiency anemia is anemia due to low iron stores in the body as mentioned in this section.

As much as one third of the world population has anemia, with approximately half of the cases resulting from iron deficiency.  A detailed discussion about the incidence and prevalence of the disease is featured in the Epidemiology section.

The development and rapidity of progress of iron-deficiency anemia depend on the individual’s iron stores, which are, in turn, dependent upon age, sex, rate of growth, and the balance between iron absorption and loss. These factors and effects are discussed further in the Pathophysiology section.

In the Etiology section causes of anemia and iron-deficiency anemia are enumerated and discussed. 

As discussed in the Classification section, iron-deficiency anemia can be classified into absolute and functional types. 

History and Physical Examination

Primary symptoms of anemia are enumerated and further explained in the Clinical Presentation section.

In the History section it is implied that it should be focused on possible etiologies of anemia. While the Physical Examination enumerates the possible physical manifestations of anemia. 

Diagnosis

Information that is necessary in diagnosing anemia and iron-deficiency anemia are featured in the Diagnosis and Diagnostic Criteria section.

In the Screening section, different screening tests that can be done are enumerated and described.

Several laboratory tests and imaging studies to be done to assess the disease are included in the Laboratory Tests and Ancillaries and Imaging sections.

Other etiologies of microcytic hypochromic anemia are enumerated in the Differential Diagnosis section.

Management

The underlying cause of iron-deficiency anemia should be treated first or referred to a specialist for specific workup and definite treatment as stated in the Principles of Therapy section.

In the Pharmacological Therapy section, oral and parenteral iron therapies for iron-deficiency anemia management are discussed.

Several non-drug options to consider that may aid in the management of iron-deficiency anemia which include dietary therapy and blood transfusion are featured in the Nonpharmacological section.  

In the Monitoring section, it is stated that correction of iron-deficiency anemia usually occurs within 2-4 months of appropriate therapy. This section discusses the tests to be done to check for effectivity of iron therapy.

Frequently Asked Questions

What are common causes of iron-deficiency anemia?
Overt blood loss is the most common and important cause of iron deficiency. Menstrual blood loss is common in premenopausal women, while gastrointestinal blood loss is more common in men and postmenopausal women. Other causes include inadequate dietary iron, malabsorption from gastrointestinal disorders or surgery, increased iron requirements during growth, pregnancy and lactation, frequent blood donation and chronic occult bleeding. Read more
Which laboratory findings confirm iron-deficiency anemia?
Laboratory findings may include decreased mean corpuscular volume, increased red cell distribution width, low serum iron, low transferrin saturation, increased total iron-binding capacity and increased soluble transferrin receptor. Serum ferritin is the most commonly available, sensitive and specific test for confirming iron deficiency. In children aged ≥5 years and adults, ferritin <15 ng/mL is diagnostic, while 15–30 ng/mL is highly suggestive of iron deficiency. Read more
When is gastrointestinal endoscopy indicated in iron deficiency?
Endoscopy is used to identify gastrointestinal lesions responsible for occult blood loss. Evaluation should be directed by gastrointestinal symptoms. Bidirectional endoscopy, including esophagogastroduodenoscopy and colonoscopy, is recommended in asymptomatic men and pre- and postmenopausal women with iron-deficiency anemia. Further evaluation may be considered when initial endoscopy is negative and iron therapy fails to correct the anemia. Read more
When is parenteral iron therapy indicated?
Parenteral iron may be used in moderate to severe iron-deficiency anemia when oral iron cannot be tolerated or absorbed, response to appropriate oral therapy is inadequate, or hemoglobin continues to fall. It may also be indicated with unresolved bleeding, inflammatory bowel disease, chronic heart failure, chronic kidney disease, or when a rapid increase in hemoglobin is required, such as before major surgery.
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How should response to iron therapy be monitored?
Correction of iron-deficiency anemia usually occurs within 2–4 months of appropriate treatment. Response may be demonstrated by reticulocytosis within 4 days and an increase in hemoglobin after 2–3 weeks. CBC may be monitored monthly for 3 months, every 3 months for 1 year, then every 6 months for 2–3 years. Lack of response warrants evaluation for nonadherence, continued blood loss, malabsorption, incorrect diagnosis or other complicating factors. Read more