Measuring haemoglobin concentration to define anaemia: WHO guidelines

Anaemia is conventionally determined when the haemoglobin concentration falls below a defined threshold for age, sex, and physiological status. 1 Weatherall DJ Hatton C Anaemia: pathophysiology, classification, and clinical features. in: Warrell DA Cox TM Firth JD Oxford textbook of medicine. 5th edn. Oxford University Press, Oxford2013 Google Scholar The accurate definition of haemoglobin concentration thresholds to determine anaemia is essential for clinical diagnosis and patient care, and for understanding the scale of the associated public health problem to plan policy and actions. WHO estimates that globally, in 2019, anaemia affected 30% of women aged 15–49 years (including 36% of all pregnant women) and 40% of children aged 6–59 months. 2 Stevens GA Paciorek CJ Flores-Urrutia MC et al. National, regional, and global estimates of anaemia by severity in women and children for 2000–19: a pooled analysis of population-representative data. Lancet Glob Health. 2022; 10: e627-e639 Summary Full Text Full Text PDF PubMed Scopus (115) Google Scholar A Global Burden of Disease Study found that in 2021, 1·9 billion people (24% of the world's population) were anaemic, and that anaemia was among the three leading causes of years of life lived with disability worldwide. 3 GBD 2021 Anaemia Collaborator GroupLevels and trends in anaemia burden by severity and cause from 1990–2021: findings from the Global Burden of Disease Study 2021. Lancet Haematol. 2023; 10: e713-e734 Summary Full Text Full Text PDF PubMed Scopus (32) Google Scholar Reducing anaemia prevalence in women is a 2025 Global Nutrition Target, and an indicator of progress towards the Sustainable Development Goals.