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Getting the latest healthcare news for you
Getting the latest healthcare news for you
A massive UK study suggests the WHO's 50-year-old anemia thresholds may be leaving patients at risk. Analyzing over 500,000 adults, researchers found that all-cause mortality was lowest in people with hemoglobin levels 1–3 g/dL above the WHO anemia cutoff — meaning even "borderline normal" levels may signal trouble. Experts say it's too soon to change clinical practice, but the findings call for a closer look at how we define anemia.
The WHO's anemia thresholds — hemoglobin below 13 g/dL in men and 12 g/dL in women — have been the clinical standard since 1959. But a sweeping new cohort study published in the Annals of Internal Medicine suggests those cutoffs may be missing a meaningful at-risk population.
Researchers analyzed data from 502,188 UK Biobank participants over a median follow-up of 13.6 years. They found a U-shaped relationship between hemoglobin levels and mortality: the highest death rates occurred in those with very low or very high hemoglobin, while the lowest mortality was seen in those with levels 1–3 g/dL above the WHO threshold — the apparent sweet spot.
By the Numbers:
Why it matters: Clinicians often consider hemoglobin levels just above the WHO threshold as reassuring — but this study suggests that "borderline normal" may still carry elevated risk, particularly in older adults and men. Experts caution that randomized trials are needed before changing practice, but screening for reversible causes like iron deficiency in borderline cases could be a meaningful first step.
