TABLE 5.
Absorption estimations from radioactive iron isotope studies across gestation1
| Radioactive isotope (59Fe as FeSO4, FeCl2, or ferric ammonium citrate) | |||||
|---|---|---|---|---|---|
| Balfour et al.4 (63) (n = 13) | Svanberg et al2,5 (64) (n = 30) | Svanberg et al2,5 (64) (n = 30) Iron treated | Hahn et al.4 (65) (n = 12–56) | Svanberg et al2,5,6 (66) (n = 22) | |
| Total iron load, mg | 1–122 | 100 | 100 | 2–9 | 4 |
| Week of gestation | Percentage uptake [range] | Mean [range] | Mean [range] | Median percentage uptake | Mean [range] |
| <10 | — | — | — | 13.8 | — |
| 10–14 | 2.7 | 6.5 [1.2–11] | 6.7 [3.4–14.5] | 13.8 | 1.5 [0–6.7] |
| 15–19 | 4.2 | — | — | 21.3 | — |
| 20–24 | 3.2 | 9.2 [3.2–17.9] | 6.0 [1.1–13.1] | 40 | 5.8 [0–15.4] |
| 25–29 | 2.5 | — | — | 41.3 | — |
| 30–34 | 16.4 | — | — | 50.6 | — |
| >35 | 9.1 [2.2–27.7] | 14.3 [5.9–24.7] | 8.6 [2.7–15.0] | 51.3 | 14.6 [5.7–28.3] |
| Fold change weeks 10–14 to >35 | 3.3 | 2.2 | 1.3 | 3.7 | 9.7 |
1
Compared with nonpregnant women (DRI 18% absorption). Hahn et al. (65) estimations were adjusted to assume 80% incorporation into RBCs because 100% incorporation was used in their publication.
2
Longitudinal study/measures across gestation.
3 Serum iron measured shortly after dosing to calculate absorption.
4
RBC iron incorporation used to calculate absorption.
5
Absorption measures using whole body counter.
6
Iron isotope dose given with food.