The World Health Organization's definition of anaemia is a haemoglobin level of less than 13g/dL for men and less than 12g/dL for women. Haemoglobin levels have been shown to decline with age, making anaemia a relatively common problem among older people. Because of this fall in haemoglobin with age, there has been some debate about whether an age-related reference range should be used. However, most clinicians believe that, because of the association between anaemia and increased risk of morbidity, mortality and hospitalization, the normal haemoglobin range should not be lowered for older people.