Unexplained Anemia of Aging

Etiology, Health Consequences, and Diagnostic Criteria

Jack Guralnik MD, PhD; William Ershler MD; Andrew Artz MD; Alejandro Lazo-Langner MD; Jeremy Walston MD; Marco Pahor MD; Luigi Ferrucci MD, PhD; William J. Evans PhD


J Am Geriatr Soc. 2022;70(3):891-899. 

In This Article

Defining Anemia Thresholds in Men and Women

The WHO definition of anemia uses different Hb thresholds for men and women, but these differences are based largely on population averages for all adults, rather than on specific clinical outcomes related to Hb values <12 g/dl for women and <13 g/dl for men. According to the WHO criteria, the prevalence of anemia increases with advancing age to a greater extent in men than in women[4] as a result of different sex-related thresholds for diagnosis. However, there is little metabolic or physiological rationale for a different threshold between postmenopausal women and older men. Importantly, women with a Hb concentration between 12.0 and 13.0 g/dl (anemic in men but not in women, according to the WHO definition) experienced a significantly lower QOL than women with Hb > 13 g/dl. Mild anemia, estimated to affect 11.1% in the population over the age of 65,[5] is defined by WHO criteria as Hb levels of 11.0–11.9 in women and 11.0–12.9 g/dl in men. The differences in these ranges (0.9 g/dl in women vs 1.9 g/dl in men) result in different therapeutic guidelines, potentially leading to undertreatment of older women with anemia. Recently, Simonsick et al.[55] examined fatigue and anemia in a cohort of older men and women from the Baltimore Longitudinal Study on Aging. They reported that even subclinical anemia, defined as Hb of 12–12.9 g/dl for women and 13–13.9 g/dl for men, was associated with fatigability. They also demonstrated that fatigability was predictive of subsequent clinical anemia. The observation that reduced QOL is observed in older women with Hb values up to 13 g/dl implies that the threshold for anemia in postmenopausal women should be similar to that in men. Such a change in diagnostic criteria would allow mild anemia in older people to be defined in the same range, and to be treated according to the same guidelines, in both sexes.