Differential associations between menstrual blood loss scores and iron status in East Asian and Northern European individuals: findings from a cross-sectional analysis of the Iron Genes in East Asian and Northern European Adults Study (FeGenes) cohort.

BACKGROUND

Healthy adult females of East Asian (EA) ancestry have been reported to have higher iron (Fe) stores and Fe absorption and alterations in Fe regulatory hormones when compared with adult females of Northern European (NE) ancestry.

OBJECTIVES

This cross-sectional study collected data on menstrual characteristics among adult females of genetically confirmed EA or NE ancestry and evaluated the potential impact of this factor on Fe status.

METHODS

Data were obtained from premenopausal females aged 18 to 50 y [BMI (in kg/m2) 18-30] who were enrolled in the FeGenes study, which recruited healthy individuals of genetically confirmed EA or NE ancestry. Data on age at menarche, cycle frequency, menstrual bleeding duration, and use of menstrual products were collected from self-reported questionnaires, and menstrual blood loss (MBL) scores were calculated. Fe status was assessed through serum ferritin (microgram per liter), hepcidin (nanograms per milliliter), soluble transferrin (TF) receptor (milligram per liter), TF (milligram per deciliter), and calculated total body Fe (milligrams per kilogram). Group comparisons and associations with Fe status biomarkers were examined.

RESULTS

EA females had an earlier median age at menarche [EA: 12.0 (IQR: 11.0, 13.0) y; NE: 13.0 (IQR: 12.0, 13.3) y; P = 0.002] and a higher MBL score [EA: 24.0 (IQR:17.5, 31.5); NE: 16.0 (IQR: 10.5, 27.9); P < 0.001] than NE females. In NE individuals, a higher MBL score was significantly associated with lower log-transformed serum ferritin (β: ‒0.01; SE: 0.005; P = 0.004), total body Fe (β: ‒0.06; SE: 0.02; P = 0.002), and higher log-transformed soluble TF receptor (β: 0.005; SE: 0.001; P = 0.002). No associations between MBL score and Fe status were evident in EA females.

CONCLUSIONS

Higher MBL scores are associated with lower Fe status in NE but not EA females. Greater attention and validated metrics are needed to evaluate MBL and better quantify Fe needs in reproductive-aged females. This trial was registered at clinicaltrials.gov as NCT04198545.