Hundreds of thousands of individuals in the UK may have a hidden blood condition, borderline anemia, that increases their risk of serious illness and early death, according to a major study published in the journal Annals of Internal Medicine. Current diagnostic guidelines for anemia, primarily caused by iron deficiency, may not identify people with low haemoglobin levels that are still within the normal range but are associated with elevated health risks.
The study, which analyzed data from nearly half a million UK Biobank participants over a decade, found that individuals with borderline anemia were more likely to die prematurely than those with higher haemoglobin levels. Haemoglobin is the protein in red blood cells responsible for carrying oxygen throughout the body.
Dr. Malek Ahmad, clinician-scientist at the University of Glasgow and lead author of the study, stated that risk begins to increase with borderline anemia, even before haemoglobin levels fall below the World Health Organization's (WHO) established thresholds. "Currently, many doctors do not even recognise a person has anaemia until its moderately severe," Ahmad noted. He suggested that the findings should encourage broader investigation and treatment for patients with mild or borderline anemia.
Anaemia is most commonly caused by iron deficiency, but can also result from a lack of vitamin B12 or folate. Symptoms can include tiredness, pale skin, irritability, and a racing heartbeat. Factors contributing to iron deficiency include insufficient dietary intake, heavy menstrual periods, pregnancy, and certain medical conditions like kidney disease. Some medications, including heartburn drugs, calcium and zinc supplements, and certain antibiotics, can also impair iron absorption.
While the study highlights an association between low haemoglobin and increased risk, researchers emphasized that it does not prove a direct causal link. They plan to investigate whether current diagnostic guidelines should be updated to incorporate factors such as diet, stress, and obesity to help physicians identify at-risk individuals earlier.
Globally, an estimated two billion people are thought to have iron deficiency, with 1.2 billion having developed iron-deficiency anemia. In the UK, approximately 3% of men and 8% of women are estimated to have the condition, leading to over 57,000 hospital admissions annually. Treatment often involves simple interventions such as daily iron supplements or dietary changes, including increased consumption of iron-rich foods like leafy vegetables and red meat.
These findings emerge amid growing concerns in the UK about a rise in hospital admissions related to deficiencies in essential vitamins and minerals, with figures indicating a significant increase in patients admitted for iron deficiency anemia and illnesses linked to low B vitamin levels. The Royal College of GPs has expressed concern that the cost-of-living crisis is making nutritious diets increasingly unaffordable for some individuals.