Iron deficiency in non-pregnant women with normal hemoglobin: a cross-sectional analysis of risk factors and clinical implications

TL;DR

Many non-pregnant women with normal hemoglobin levels still have iron deficiency, with breastfeeding and a history of anemia being key risk factors.

Contribution

This study highlights the underdiagnosed prevalence of iron deficiency in non-pregnant women with normal hemoglobin and identifies key risk factors.

Findings

41% of non-pregnant women with normal hemoglobin levels had iron deficiency.

Breastfeeding history and a history of anemia were strongly associated with iron deficiency.

A comprehensive iron assessment is recommended for at-risk populations.

Abstract

Iron deficiency without anemia (IDWA) is a widespread but underdiagnosed condition in women of reproductive age. Traditional screening approaches that rely solely on hemoglobin levels may overlook significant iron depletion in seemingly healthy female patients, leading to missed opportunities for intervention against impaired cognition, reduced exercise capacity, and an increased risk of infection in this population.

The objective of the study was to determine the prevalence of iron deficiency in non-pregnant women with normal hemoglobin levels and to identify the factors associated with iron deficiency.

This cross-sectional study was conducted at an urban teaching hospital between March and August 2024. A total of 127 non-pregnant women aged 16–45 years were eligible; 100 women with hemoglobin levels ≥11 g/dL were enrolled using consecutive sampling (refusal rate: 21.3%, n = 27). Data on demographic characteristics, clinical history, reproductive factors, dietary habits, and laboratory evaluations (hemoglobin, serum ferritin, and serum iron levels) were collected for each patient. Iron deficiency was defined as a serum ferritin level of <15 μg/L or a serum iron level of <10 μmol/L. A multivariable logistic regression analysis was adjusted for age, BMI, parity, dietary patterns, physical activity, and iron supplementation.

Iron deficiency was identified in 41% (41/100) of the participants despite normal hemoglobin levels. A univariate analysis revealed significant associations between iron deficiency and a history of breastfeeding (crude OR = 9.13, 95% CI: 3.32–25.11, p < 0.001) and of anemia (crude OR = 5.51, 95% CI: 2.10–14.46, p < 0.001). After multivariable adjustment, breastfeeding history remained strongly associated with iron deficiency (adjusted OR = 6.72, 95% CI: 2.01–22.44, p = 0.002), as well as with history of anemia (adjusted OR = 4.92, 95% CI: 1.56–15.53, p = 0.007). Underweight BMI showed an elevated point estimate but did not reach statistical significance (adjusted OR = 2.84, 95% CI: 0.68–11.83, p = 0.154), likely due to the limited sample size in this subgroup. Model diagnostics were satisfactory (Hosmer–Lemeshow χ2 = 3.21, p = 0.921; all variance inflation factors (VIFs) < 2.0).

A substantial proportion of non-pregnant women with normal hemoglobin levels demonstrated biochemical evidence of iron deficiency. Breastfeeding history and a history of anemia were the strongest independent factors associated with iron deficiency. A comprehensive iron assessment, including ferritin and serum iron levels, is recommended for at-risk populations, particularly those with a history of breastfeeding or anemia.

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