Absorption of Inorganic Iron in Thalassaemia

Abstract

THE STUDY of selective factors responsible for the maintenance of the thalassaemic gene in a well-defined population has been the subject of interest to several investigators in the last decade. It is thought that, as a result of certain biological advantages, a greater number of thalassaemic heterozygotes survive into reproductive life thus compensating for the continuous loss of the homozygous form of the disease.The first biological advantage in this balanced polymorphism proposed by Haldane (1945) was malarial infection. According to this author individuals harbouring the abnormal thalassacmic gene were found to be more resistant against invasion by the parasite. Studies on the incidence of thalassaemia in populations with a past or present history of malaria by Carcassi, Ceppellini and Pitzus (1957) have given support to Haldane's hypothesis. Recently Stamatoyannopoulos and Fessas (1964) found that, compared to the sickle-cell disease and G6PD deficiency, thalassaemia is the least efficient abnormality protecting against malaria. Further investigations on this relationship are at present being pursued.The second selective biological advantage is based on a totally di&=rent mechanism and was proposed by Sijpesteijn (1958). This investigator suggested that the heterozygote thalassaemic enjoyed a greater protection against iron deficiency than the normal individual. The mild chronic anaemia in women affected with this abnormal gene might enhance iron absorption with increased storage in the tissues. This hypothesis could not be confirmed by several Italian investigators. Rannerman and Callender (1961) have studied iron absorption in 17 heterozygote thalassaemics using haemoglobin labelled with 59Fe and inorganic 5 9 Fe.Their results have challenged the theory of enhanced iron absorption. Lately the same authors (Bannerman, Callender, Hardisty and Sephton Smith, 1964) have extended their investigations to homozygous thalassaemic children as well as heterozygous adults. Although there was wide scatter in iron absorption in their subjects, the mean absorption in both groups did not differ from the normal control receiving the same form of iron. The present study is intended further to investigate iron absorption in thalassaemia. MATERIAL AND METHODSThe clinical material studied consisted of five unrelated families. The diagnosis of thalassaemia was based on the clinical picture, the characteristic morphology of the peripheral blood and the biochemical findings. In each instance at least one member of the family has suffered or was suffering from the honiozygous form of the disease while others were classified as thalassaemia minor or were found to be normal. In all these subjects routine haematological investigations (haemoglobin, haematocrit, red cell morphology, red cell osmotic fragility, reticulocyte count, etc.) as well as biochemical studies (serum iron and ironbinding capacity, determination of foetal haemoglobin and the A2 fraction, etc.) were performed according to standard methods. Diagnosis of the maj...

Beta‐thalassaemia Minor During Pregnancy, With Particular Reference to Iron Status

“…Iron absorption is normal, but iron utilization is reduced in thalassaemia minor (Bannerman and Callender, 1961 ;Shahid and Abu Haydar, 1967), and haemosiderosis has been reported as a complication of thalassaemia minor in only one family, when the two conditions of excess iron storage and thalassaemia were seen to be the result of two genes which dissociated in the next generation (Bowdler and Huehns, 1963). None of the patients in the present series had more than 43 per cent saturation of TIBC (Table Il), but four had large aggregates of iron in their bone marrows.…”

Iron Absorption in Patients with β-Thalassaemia/ Haemoglobin E Disease and the Effect of Splenectomy

“…Among others, Shahid and Abu Haydar [5] reported on increased iron absorption in homozygous /Fthalassaemia. Our find ings reveal for the first time that absorp tion of inorganic iron is significantly high er in patients with /j-thalassaemia/Hb E disease than in normals.…”

“…Well-studied cases have been re ported in which more iron was found at necropsy than could be accounted for by the transfusions received, and in some of the earlier reports heavy iron deposition was noted in cases who had never been transfused. Absorption of iron from food represents a further possible source of iron loading in these patients [5].…”

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

“…The 59Fe absorption by the control subjects in this study was, however, much lower than described by other laboratories (Table 5) and may be the reason for the misinterpretation of 5~Fe absorption measurements in the patients with heterozygous fl-thalassemia. Other laboratories have described for patients with heterozygous thalassemia a normal 59Fe-absorption from a 5--10 mg dose of 59Fe2+ [9,1,27] and a normal or reduced absorption from a 5 mg dose of 59Fe-labeled hemoglobin-iron [1] ( Table 5). The amount of available storage iron in the bone marrow macrophages was not investigated and correlated with the intestinal iron absorption in these previous studies, so that depleted iron stores in prelatent iron deficiency may have caused the increased iron absorption described in some patients with heterozygous fl-thalassemia and also found in the control groups.…”