Iron status at opposite ends of the menstrual function spectrum

Although exercising women are at high risk of poor iron status, it is unknown how non-pathological, physiological menstrual function affects iron status. As such, this study investigates the association between menstrual function and iron status in exercising women with amenorrhea and exercising women with ovulatory, eumenorrheic menstrual cycles.

Cross-sectional analysis of iron depletion prevalence, iron status indices, exercise parameters, and diet composition.

Women aged 18-35 years performing at least 2 h per week of aerobic exercise were recruited. Women with amenorrhea (AMEN) were defined by the absence of menses for at least 90 days or less than 6 menses in the past 12 months (n = 82). Women with ovulatory, eumenorrheic menstrual cycles (OvEU) were defined by the presence of ovulatory cycles of 26-35 days in length for the past 6 months (n = 109). Group differences in serum ferritin (Ft), soluble transferrin receptor (sTfR), total body iron (TBI), hemoglobin (Hb), hematocrit (Hct), iron depletion prevalence (Ft <15 μg/L), peak oxygen consumption (VO_2peak), exercise minutes per week, and diet logs were assessed.

The prevalence of iron depletion was greater in OvEU when compared to AMEN (26% vs. 15%, p = 0.04). No significant differences were observed between AMEN and OvEU in Ft (30.2 ± 2.2 vs. 24.9 ± 2.6 μg/L; p = 0.62), sTfR (5.2 ± 1.4 vs. 4.9 ± 1.5 mg/L; p = 0.95), TBI (5.3 ± 2.7 vs. 4.8 ± 3.7 mg/kg; p = 0.42), Hb (13.2 ± 0.4 vs. 13.4 ± 0.6 g/dL; p = 0.80), Hct (39.5 ± 0.8% vs. 39.8 ± 4.1%; p = 0.93), or exercise parameters. AMEN consumed more vitamin C than OvEU (269 ± 180 vs. 129 ± 141 mg/day, p < 0.001), but all other dietary factors were similar between AMEN and OvEU.

Exercising women with ovulatory, eumenorrheic cycles are at a greater risk of iron depletion than exercising, amenorrheic women. Thus, menstrual function must be considered when screening for poor iron status in exercising women.