Rethinking the Physiological Anemia of Aging: Evidence from Age-Stratified Determinants of Hemoglobin

Background: (Hb) is the primary biomarker for diagnosing and monitoring anemia in clinical and public health settings. Although Hb levels decline with age, this pattern is often accepted as a normal part of aging, without adequate consideration of modifiable factors such as iron status and inflammation. This oversight may lead to misclassification of anemia etiology, especially in older adults. Methods : A cross-sectional study was conducted in Baghdad, Iraq, among 600 individuals aged 20–70 years, including healthy individuals and those with chronic inflammatory diseases. The participants were divided into young (20–39 years), middle-aged (40–59 years), and old (60 years and above) groups. Multivariate linear regression, including age-stratification, was used to determine independent determinants of hemoglobin, with special attention to iron status (log-transformed serum ferritin), inflammation (hs-CRP > 3.0 mg/L), smoking, chronic kidney disease, and nutritional deficiencies. Results : After adjustment for covariates, the association between age and hemoglobin was substantially attenuated. Elevated hs-CRP was strongly associated with lower hemoglobin in young adults (β = −1.55 g/dL) and moderately associated in older adults (β = −0.79 g/dL). Serum ferritin was a significant positive determinant of hemoglobin in middle-aged and older adults, but not in young adults. Smoking was associated with higher hemoglobin only in young adults. The models explained approximately 45–55% of the variability in hemoglobin within each age stratum. Conclusions : Variation in hemoglobin concentration among Iraqi adults is primarily related to iron status and systemic inflammation rather than chronological age. These findings challenge the use of age-specific hemoglobin cutoffs without consideration of inflammation and iron status, and suggest that anemia in older adults should not be dismissed as an inevitable consequence of aging.