Page 77 - Haematologica May 2020

Iron absorption from oral supplements in anemia
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B
Figure 3. Iron absorption in iron-deficient anemic women. (A) Fractional iron absorption from 100 and 200 mg oral iron doses was higher during alternate day dosing (day 5) compared to consecutive day dosing (day 3); (B) Total iron absorption from 100 and 200 mg oral iron doses was higher during alternate day dosing (day 5) compared to consecutive day dosing (day 3).
Figure 4. Serum hepcidin and transferrin saturation profiles in iron-deficient anemic women. (A) Serum hepcidin (Shep) profile during alternate day dosing (day 5) and consecutive day dosing (day 3) with 100 and 200 mg oral iron; (B) Transferrin saturation profile (TSAT) during alternate day dosing (day 5) and consecutive day dosing (day 3) with 100 and 200 mg oral iron.
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(alternate) days, alternate day dosing resulted in a 34% higher FIA compared to consecutive day dosing.17 In the current study, there was no residual absorption inhibition at 48 h post-administration; this is evidence against the postulate of a mucosal block lasting up to 5 or 6 days.26 This finding suggests that increasing the dosing interval beyond 48 h would not result in a further increase in iron absorption. Taken together, the available data suggest that in iron-deficient women with or without anemia, alternate day dosing with oral iron doses in the range of 60 to 200 mg results in a sharply higher FIA compared to daily dosing.
In this study, FIA from 200 mg was significantly lower compared to FIA from 100 mg iron (P<0.001). Thus, even in iron-deficient anemic women, who are maximizing enterocyte iron uptake from the gut lumen by upregula- tion of divalent metal transporter 1 (DMT1) expression,27 and who are maximizing enterocyte iron transfer to the
circulation via low baseline SHep and high ferroportin expression, low oral iron doses are more efficiently absorbed than higher doses. Previous studies have gener- ally demonstrated that FIA of oral iron decreases with increasing dose, but many of these studies were done in non-anemic subjects.8 In this study, there was no signifi- cant difference in FIA comparing daily dosing (day 3) with 100 mg versus alternate day dosing with 200 mg (day 5). Consequently, TIA from a single dose of 200 mg given on alternate days was approximately twice that from 100 mg given on consecutive days (P<0.001). This suggests that TIA would be similar from alternate day dosing of 200 mg compared to daily dosing of 100 mg.
In women with IDA, the SHep increase of ~0.4 nM after doses of 100 and 200 mg was much smaller than the SHep increase of ~2 nM (about 1.85 nM after correction for method comparison)28 after doses of 120 mg in non- anemic iron depleted women.8 A potential explanation
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Fractional absorption (%)
Total absorption (mg)