Assessing the iron status of populations
Second edition, including Literature Reviews
Anaemia is one of the most common and intractable nutritional problems in the world today. The World Health Organization (WHO) estimates that some two billion people are anaemic defined as haemoglobin concentrations that are below recommended thresholds. The main causes of anaemia are: dietary iron deficiency; infectious diseases such as malaria, hookworm infections and schistosomiasis; deficiencies of other key micronutrients including folate, vitamin B12 and vitamin A; or inherited conditions that affect red blood cells (RBCs), such as thalassaemia.
In the absence of international agreement on how to assess the iron status of populations, the prevalence of iron deficiency has often been derived from the prevalence of anaemia using measurements of blood haemoglobin concentration. However not all anaemic people are iron deficient and iron deficiency may occur without anaemia. This means that the prevalence of anaemia and iron deficiency varies in different populations and no consistent relationship between the two can be applied throughout the world. When anaemia is considered from the point of view of programmes to improve nutrition and health, an estimate of the prevalence derived from the haemoglobin concentration alone does not allow the contribution of iron deficiency to anaemia to be estimated, and ignores the role of other causes of anaemia.
To plan effective interventions to combat both iron deficiency and anaemia there is an urgent need to have better information on the iron status of populations. This will enable the right interventions to be chosen in the first place and then, once programmes are in place, to have the right indicators to monitor their impact.
These were all reasons for holding the Joint WHO/Centers for Disease Control and Prevention (CDC) Technical Consultation on the Assessment of Iron Status at the Population Level. The Consultation took place in Geneva, Switzerland, from 6 to 8 April 2004.
The objectives of the Consultation were to review the indicators currently available to assess iron status; to select the best indicators to assess the iron status of populations; to select the best indicators to evaluate the impact of interventions to control iron deficiency in populations; and to identify priorities for research related to assessing the iron status of populations.
The Consultation was provided with literature reviews on indicators of iron status, including RBC parameters, ferritin, free erthyrocyte protoporphyrin, serum and plasma iron, total iron binding capacity, transferrin saturation and serum transferrin receptor as well as a review on the interpretation of indicators of iron status during an acute phase response. These reviews provide technical background to the measurement, biology, interpretation and diagnostic value of the indicators.