Comparative Absorption of Ferri‐Haemoglobin‐⁵⁹Fe/Ferro‐Haemoglobin‐⁵⁹Fe and ⁵⁹Fe³⁺/⁵⁹Fe²⁺ in Humans with Normal and Depleted Iron Stores*

Abstract

Abstract. The intestinal 59Fe absorption from ferri‐ and ferro‐haemogIobin‐59Fe and 59Fe3+ and 59Fe+ was calculated from whole body‐59Fe‐retention measurements in subjects with normal and depleted iron stores. A ferri‐haemoglobin‐59Fe/ferro‐haemoglobin‐59Fe absorption ratio of 1.03 ±0.11 was observed for the absorption of ferri‐haemoglobin‐59Fe (8.6± 0.77%) and ferro‐haemogIobin‐59Fe (8.7±0.94%) in persons with normal iron stores. Depletion of iron stores caused a slight but significant higher rise of ferri‐haemoglobin‐59Fe absorption (22 ± 1.7%) than the increase of ferro‐haemoglobin‐59Fe absorption (18 ±0.9%) so that the absorption ratio was 1.24±0.073.—This remarkable iron valence independence of haemoglobin iron absorption is in considerable contrast to the well‐established valence dependence of inorganic iron absorption which favours ferrous iron absorption especially with rising iron doses. The 59Fe3+/59Fe2+ absorption ratio for a diagnostic 0.56 mg Fe dose increased from 0.43 in subjects with normal iron stores to 0.74 in persons with depleted iron stores, whereas this absorption ratio was augmented only from 0.21 to 0.28 for the therapeutic 50 mg Fe‐dose.—The different influence of iron valence on iron absorption from inorganic and haemoglobin iron supports other evidence for the existence of two separate mechanisms for ferrous iron and haem iron absorption in humans.

Absorption of inorganic and food iron in children with heterozygous and homozygous ?-thalassemia

“…Depleted iron stores as a reason for increased iron absorption are impossible in children with homozygous /~-thalassemia. A hemoglobin-59Fe-absorption of 20 • 18% (range: 5--65% ; see Table 5) as observed in children with homozygous fl-thalassemia should not be considered to be normal or even reduced [1] since it is comparable to the average absorption in subjects with depleted iron stores and 2 to 3 times as high as in control subjects with normal iron stores [18,19].…”

“…Control subjects with normal iron stores were reported to absorb 3.3--12 (~a • S.D. = 7.5 :k 2.4)% of a 5 mg dose of 59Fe-labeled hemoglobin-iron, whereas subjects with depleted iron stores (prelatent iron deficiency) absorbed 10--29 (xa ~= S. D. = 18 ~ 5.3)% [18,19]. Considering these absorption ranges for ~ZFe-labeled hemoglobin, seven out of the eight control children in the study of Bannerman et al (1964) would have absorbed amounts within the elevated range observed in subjects with depleted iron stores (prelatent iron deficiency).…”

“…To avoid any interference with the absorption of 59Fe~+ no meals and no beverages (with the exception of plain water) were allowed for 5 hrs (children under 2 years of age) or 12 hrs (older children) before and 2 hrs after the oral administration of the ~SFe~+. SgFe-labelled pork, liver and hemoglobin were prepared by administering intravenous doses of 4--5 mCi of radioehemically pure SgFe3+Cla to pigs [18,19]. Samples containing 5 mg iron in 200 g pork, 25 g liver or 1.44 g hemoglobin were fed to a fasted 10-year-old child with homozygous fl-thalassemia.…”

Iron Absorption from Hemiglobin (Stable Oxidation Product of Hemoglobin) in Relation to the Dose in Subjects with Normal and Depleted Iron Stores

“…The hemiglobin was prepared from the heparinized blood between 1968 and 1972 by hemolyzation of the washed erythrocytes, successive precipitation of the membranes and stroma proteins at pH 5.8 and 7.1 and final oxidation to hemiglobin by adding 0.4 ml of a 0.25 M NaNOj solution to 1.44 g hemoglobin (= 5 mg Fe) samples (Heinrich et al, 1969(Heinrich et al, , 1971a. Since 1973, a modified procedure was used for the preparation of hemoglobin-5,'Fe and its oxidation to hemiglobin-s,Fc.…”

“…The dose relationship of inorganic iron was found to be characterized for the dose range between 0.56 and 50 mg by straight lines in bilogarithmic plots both for ferrous {Heinrich et al, 1969b;Heinrich, 1970a) and ferric iron {Gabbe, 1975;Heinrich, 1975a) if the subjects were separated into groups with normal and depleted iron stores. Since it was recommended to use hemiglobin or hemoglobin for the prophylaxis and therapy of iron deficiency {Heinrich et al, 1969a, 1971aReizenstein, 1975\Reizen-stein et al, 1975 as well as for the iron enrichment of the diet (Heinrich et al, 1971c) it became necessary to investigate the dose relationship of hemiglobin iron absorption in subjects with normal and depleted iron stores.…”