WHO Guidelines for Anemia: Defining, Diagnosing, and Managing Globally

December 29, 2025 •

4 min read

According to the World Health Organization (WHO), anemia is a serious public health problem that affects over 500 million women and 250 million children worldwide. These pervasive statistics underscore the critical need for clear, evidence-based WHO guidelines for anemia to effectively define, diagnose, and manage this condition across different global populations.

Quick Summary

This article details the World Health Organization's evidence-based guidance for anemia, including updated hemoglobin cutoff values for various groups, the importance of considering multiple contributing factors beyond iron deficiency, and specific recommendations for prevention and treatment strategies.

Key Points

Updated Hemoglobin Cutoffs: The 2024 WHO guidelines introduced new, more specific hemoglobin thresholds for children aged 6–23 months and for pregnant women in the second trimester.
Altitude and Smoking Adjustment: Haemoglobin levels must be adjusted for individuals living at high altitudes or who smoke to ensure accurate anemia diagnosis.
Multifactorial Diagnosis: Diagnosing anemia requires looking beyond hemoglobin levels to consider red blood cell morphology, iron studies, and inflammatory markers.
Comprehensive Management: Treatment focuses on addressing the specific cause, which could involve nutritional supplementation, infection control, or managing chronic diseases.
Integrated Prevention: Prevention is key, involving dietary improvements, food fortification, parasite control, and promotion of exclusive breastfeeding.
Multisectoral Approach: Effective anemia reduction requires coordinated efforts across multiple sectors, including health, nutrition, and sanitation.
Severity Classification: The guidelines maintain a classification system for mild, moderate, and severe anemia based on hemoglobin concentration thresholds.
Public Health Significance: Anemia prevalence is classified as a public health issue of normal, mild, moderate, or severe significance based on population-level data.

Defining Anemia: The Latest WHO Haemoglobin Cutoffs

Anaemia is a condition characterized by a lower-than-normal number of red blood cells or a reduced haemoglobin concentration, leading to decreased oxygen-carrying capacity in the blood. In March 2024, the WHO released updated guidelines for defining anemia based on specific haemoglobin (Hb) cutoffs for different age groups, sexes, and physiological states. These updated thresholds reflect a more nuanced understanding of normal haemoglobin values, incorporating factors like elevation and smoking status.

Updated Haemoglobin Cutoffs by Population

The most recent guidelines from the WHO recommend the following haemoglobin thresholds to define anemia, based on measurements taken at sea level:

Children 6–23 months: <10.5 g/dL
Children 24–59 months: <11.0 g/dL
Children 5–11 years: <11.5 g/dL
Children 12–14 years (non-pregnant girls and boys): <12.0 g/dL
Non-pregnant women (15+ years): <12.0 g/dL
Pregnant women (1st and 3rd trimesters): <11.0 g/dL
Pregnant women (2nd trimester): <10.5 g/dL
Men (15+ years): <13.0 g/dL

Adjustments to these haemoglobin levels are recommended for individuals living at high altitudes or those who smoke. The WHO also maintains its classification of anaemia severity (mild, moderate, severe) based on these updated haemoglobin concentrations.

Diagnostic Approach Beyond Haemoglobin Measurement

While haemoglobin concentration is the primary biomarker for diagnosing anemia, the WHO emphasizes a comprehensive approach to determine the underlying cause. A full diagnostic workup often includes evaluating additional hematological parameters to differentiate between nutritional deficiencies, chronic diseases, and other contributing factors.

Classifying Anemia Beyond Just Hb Levels

Anemia can be categorized by the size of the red blood cells, which is measured by the Mean Corpuscular Volume (MCV).

Microcytic Anemia (low MCV): Characterized by small red blood cells, this is typically associated with iron deficiency or thalassemia.
Normocytic Anemia (normal MCV): Involving red blood cells of normal size, this can result from acute blood loss, chronic disease, or early stage deficiencies.
Macrocytic Anemia (high MCV): Defined by large red blood cells, this is often caused by deficiencies in vitamin B12 or folate.

Further investigations may involve an iron profile (serum ferritin, transferrin saturation) and, when warranted, a reticulocyte count to assess the bone marrow's red blood cell production response. For individuals with inflammation or infection, serum ferritin levels can be misleading, so the WHO recommends measuring additional markers like C-reactive protein (CRP).

Management and Prevention Strategies

The WHO provides a comprehensive framework for managing and preventing anemia that extends beyond simple supplementation, emphasizing a multisectoral approach. Treatment plans are individualized based on the specific cause, while prevention efforts focus on nutrition, infection control, and addressing socio-economic factors.

Nutritional Interventions

For nutritional anemias, the WHO advocates for a multi-pronged strategy:

Dietary Diversity: Promoting a diet rich in iron, folate, vitamin B12, and vitamin A through education and access to healthy foods.
Supplementation: In high-prevalence settings, targeted iron and folic acid supplementation is recommended for specific at-risk groups, such as children and women of reproductive age.
Food Fortification: The fortification of staple foods like wheat and maize flour with iron and folic acid is advised to improve population-level nutrient intake.

Disease Control and Management

Anaemia is often a symptom of underlying health issues, requiring targeted disease management:

Infection Control: Prevention and treatment of infectious diseases like malaria and soil-transmitted helminths are crucial in endemic areas.
Chronic Disease Management: Addressing conditions such as obesity, renal disease, or other inflammatory states can help improve anemia outcomes.
Inherited Disorders: For conditions like sickle-cell disease and thalassemia, specialized management is necessary.

Comparison of Old vs. New WHO Hemoglobin Cutoffs

To highlight the impact of the latest revisions, a comparison of the old versus the 2024 WHO hemoglobin cutoffs is helpful:


Population Group	Previous WHO Cutoff (g/dL)	2024 WHO Cutoff (g/dL)	Key Change	Notes
Children 6–23 months	<11.0	<10.5	Lowered threshold	Reflects new data on healthy populations
Children 24–59 months	<11.0	<11.0	Unchanged	Cutoff remains the same
Pregnant Women (2nd Trimester)	<11.0 (combined)	<10.5	Lowered threshold	Now trimester-specific for increased accuracy
Non-Pregnant Women (15+ years)	<12.0	<12.0	Unchanged	Cutoff remains standard
Men (15+ years)	<13.0	<13.0	Unchanged	Cutoff remains standard

Conclusion

The WHO guidelines for anemia have evolved to provide a more precise and comprehensive framework for addressing this global health issue. By establishing updated, population-specific haemoglobin cutoffs and advocating for a holistic approach to diagnosis and treatment, the WHO aims to accelerate progress toward its global nutrition targets. Beyond relying solely on supplementation, the guidelines stress the importance of understanding multifactorial causes, promoting dietary diversity, managing underlying diseases, and implementing a multisectoral public health response. This evidence-informed strategy is crucial for effective prevention and management, ultimately improving health outcomes and reducing the socioeconomic burden of anemia worldwide.

Further information on the comprehensive framework for action is available on the official WHO website: Accelerating anaemia reduction: a comprehensive framework for action.

Frequently Asked Questions

The key updates include revised hemoglobin (Hb) cutoff values, specifically a lower threshold for children 6–23 months old and trimester-specific cutoffs for pregnant women.

The WHO recommends adjusting hemoglobin concentrations to account for the effect of elevation, as higher altitudes can naturally increase hemoglobin levels.

Common symptoms include fatigue, weakness, dizziness, light-headedness, and shortness of breath, with severity depending on the degree of anemia.

The WHO recognizes that anemia can be caused by infections (like malaria), inflammation, chronic diseases, and deficiencies in other nutrients such as folate, vitamin B12, and vitamin A.

Prevention strategies include dietary diversity, food fortification programs, and targeted iron supplementation for high-risk populations, such as women and young children.

For severe anemia, treatment involves addressing the underlying cause. In cases of severe iron deficiency, oral or intravenous iron therapy may be necessary. Blood transfusions are reserved for severely symptomatic patients or those with critical complications.

The latest guidelines use trimester-specific hemoglobin thresholds. Anaemia is defined as Hb <11.0 g/dL in the first and third trimesters, and Hb <10.5 g/dL in the second trimester.

A multisectoral approach is recommended because the causes of anemia are complex and often linked to factors beyond diet, such as infections, poor sanitation, and socioeconomic issues.