Slightly Low Hemoglobin May Raise Mortality Odds
A prospective cohort study found that adults with borderline anemia—hemoglobin levels 0 to 1 g/dL above the WHO threshold—had an 18% higher 10-year standardized cumulative incidence of all-cause mortality compared with a reference group. The risk was elevated for all-cause, cardiovascular, and cancer mortality in men of all ages and in women 60 and older. Researchers suggest that a single diagnostic cutoff may not capture the relationship between hemoglobin and long-term health.
A large U.K. Biobank cohort of 502,188 adults, recruited between 2006 and 2010 with a median age of 58, provided the data. Compared with a reference group showing a 4.5% 10-year cumulative mortality incidence, those with borderline anemia reached 5.3%, reflecting an 18% relative increase. The researchers noted a U-shaped pattern, with elevated risks at both low and high hemoglobin extremes.
Stratified findings showed heightened risks for all-cause, cardiovascular, and cancer mortality among men of every age and women aged 60 or older. The authors suggest that hemoglobin readings just above the anemia threshold could warrant clinical investigation—especially in older adults or those with heart disease—rather than automatic reassurance, given the prevalence of iron deficiency in these groups.
This finding could reshape routine screening for older adults, as millions currently deemed "normal" may actually face elevated mortality risks. Clinicians might need to interpret hemoglobin levels more contextually, potentially prompting earlier iron-deficiency testing or cardiovascular assessments. Public health guidelines could eventually adopt age- and sex-specific thresholds, though further validation is needed. For aging populations where mild anemia is common, this may encourage more proactive monitoring and earlier interventions, potentially reducing long-term mortality.