Anemia, defined by a low number of healthy red blood cells or reduced hemoglobin concentration, limits the blood’s ability to carry oxygen throughout the body and is recognized by the World Health Organization (WHO) as a major global public health concern, particularly affecting women and young children. To standardize efforts, the WHO issues evidence-based guidelines that establish diagnostic criteria, outline prevention strategies, and standardize clinical management protocols. These standards help national health systems accurately assess the problem and implement effective public health interventions.
Defining Anemia by WHO Standards
The WHO defines anemia using specific hemoglobin (Hb) concentration cutoffs, measured in grams per liter (g/L), which vary depending on age, sex, and physiological status. For non-pregnant women aged 15–65 years, anemia is defined as a hemoglobin concentration below 120 g/L. For adult men in the same age range, the cutoff is lower than 130 g/L, while pregnant women and children aged 6–59 months have a lower threshold of 110 g/L.
Beyond the initial diagnosis, the WHO further classifies anemia into levels of severity to guide appropriate treatment and public health response. The classification distinguishes between mild, moderate, and severe cases based on how far the hemoglobin level falls below the normal cutoff for that specific demographic group. For instance, a non-pregnant woman is considered to have moderate anemia if her hemoglobin falls between 80–109 g/L, while a severe case is indicated by a level below 80 g/L. These precise classifications allow health programs to accurately categorize the burden of disease within a population and prioritize resources effectively.
Global Prevention Strategies
Prevention is central to the WHO’s strategy, focusing on prophylactic measures, especially for the most vulnerable groups. One primary recommendation is the provision of iron and folic acid supplementation, advised as a daily dose for pregnant women to reduce the risk of maternal anemia and poor birth outcomes. The daily prophylactic dose ranges from 30 to 60 mg of elemental iron combined with 400 µg of folic acid, starting as early as possible in pregnancy.
For menstruating women in populations where the prevalence of anemia is 20% or higher, the WHO recommends intermittent supplementation to improve iron status and hemoglobin concentrations. A common intermittent regimen advises a weekly dose of 60 mg of elemental iron combined with 2.8 mg of folic acid, typically administered for three months, followed by a three-month break. This alternative schedule is often better tolerated than daily dosing, which can increase adherence in public health programs.
An additional strategy involves the fortification of staple foods with iron and other essential micronutrients to boost population-wide nutrient intake. This approach provides a steady, low-dose supply of nutrients through widely consumed foods without requiring individual compliance. Furthermore, the WHO emphasizes controlling infectious diseases, as non-nutritional factors contribute significantly to anemia. This includes implementing deworming programs for soil-transmitted helminths and distributing insecticide-treated nets for malaria prevention in endemic regions.
Clinical Management Protocols
Once an individual is diagnosed with anemia, the focus shifts to intervention. For cases of mild to moderate iron-deficiency anemia, treatment involves higher-dose oral iron supplementation, often 150–200 mg of elemental iron per day. This higher dose is necessary to correct the hemoglobin deficit and fully replenish the body’s iron stores, typically requiring continued treatment for at least three months after the hemoglobin returns to normal.
Managing severe anemia, generally defined by a hemoglobin level below 70 g/L, requires immediate and coordinated clinical care. Protocols prioritize stabilizing the patient and may involve a blood transfusion for individuals who are symptomatic, such as those experiencing signs of shock, respiratory distress, or cardiovascular complications. For a stable patient without underlying heart disease, a restrictive transfusion threshold of 70 g/L is often applied, but patients with pre-existing cardiovascular conditions may require transfusion at a slightly higher hemoglobin level.
A comprehensive management plan necessitates identifying and treating all non-nutritional causes that may be contributing to the patient’s condition. This may include screening for chronic infections, addressing underlying inflammatory diseases, or investigating genetic disorders like thalassemia or sickle cell disease. Effective clinical management involves a multi-faceted approach where therapeutic supplementation is combined with the specific treatment of any identified root cause.
Programmatic Monitoring and Evaluation
The WHO guidelines extend their scope beyond individual patient care to inform national health policy and public health program management. The guidelines establish a system for categorizing the public health significance of anemia based on its prevalence within a population. For example, a prevalence rate of 20–39% is categorized as a moderate public health problem, while 40% or more indicates a severe problem requiring an urgent, large-scale response.
National health systems use these standardized thresholds to conduct surveillance and track the burden of anemia over time. This allows countries to translate the global guidelines into relevant national health policies and implementation strategies that target the most affected areas. The WHO encourages the use of these metrics to evaluate the success of national anemia reduction programs against global targets, such as the goal to achieve a 50% reduction of anemia in women of reproductive age.
Monitoring and evaluation efforts assess both the coverage of interventions, like supplementation or food fortification programs, and the actual impact on population-level hemoglobin levels. By systematically collecting and analyzing data based on WHO standards, countries can determine which strategies are succeeding and adjust their approach to ensure resources are used efficiently to reduce anemia prevalence and improve overall public health outcomes.