Table 1.
Characteristics of study subjects with and without suboptimal iron status.
| Characteristic | Subjects with sufficient iron stores (n = 305)a | Subjects with suboptimal iron status (n = 70)b | P valuec |
|---|---|---|---|
| Age (year) | 27.5 ± 8.4 | 30.1 ± 9.0 | 0.02 |
| BMI (kg/m2) | 23.5 ± 4.1 | 23.0 ± 3.2 | 0.35 |
| SF (μg/L) | 52.9 ± 27.0 | 13.0 ± 4.3 | <0.001 |
| Hb (g/L) | 133.7 ± 8.0 | 124.9 ± 10.5 | <0.001 |
| Ethnicity | |||
| European | 239 (78.6) | 43 (61.4) | 0.002 |
| Asian | 36 (11.8) | 20 (28.6) | |
| Other | 29 (9.5) | 7 (10.0) | |
| Born in New Zealand | 177 (58.2) | 35 (50.0) | 0.23 |
| Having children | 80 (26.3) | 32 (45.7) | 0.002 |
| Any blood donation in the past year | 24 (7.9) | 19 (27.1) | <0.001 |
| Having nose bleeds | 30 (9.9) | 8 (11.4) | 0.83 |
| Estimated menstrual blood loss (blood loss units) | 39.0 ± 31.5 | 45.8 ± 32.8 | 0.137 |
| Duration of menstrual period (d) | 4.9 ± 1.4 | 5.4 ± 1.4 | 0.004 |
| Using oral contraception | 99 (32.7) | 12 (17.1) | 0.013 |
| Using intrauterine deviced | 17 (5.6) | 2 (2.9) | 0.547 |
| Used low dose iron supplements or multivitamins in the past year | 87 (28.7) | 21 (30.0) | 0.88 |
| Previous iron deficiency | 116 (38.2) | 39 (55.7) | 0.01 |
| Smokerd | 21 (6.9) | 3 (4.3) | 0.591 |
Data are mean ± standard deviation or n (%).
aSF ≥ 20 μg/L and Hb ≥ 120 g/L.
bSF < 20 μg/L (Hb < 120 or ≥120 g/L).
c P value is for a test of differences between groups as assessed by the independent t-test (continuous data) or chi-square test (categorical data) (adequate expected values).
dDifference between groups assessed using Fisher's exact test as expected values <5.0.
BMI: body mass index; Hb: hemoglobin; SF: serum ferritin.