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Cardiac Hypertrophy, Heart Failure and Cardiomyopathy
Published in Mary N. Sheppard, Practical Cardiovascular Pathology, 2022
In both primary haemochromatosis due to increased intestinal absorption of iron, and in chronic haemolytic anaemias treated by transfusion, excess iron may be deposited in the myocardium. One in 200 Caucasian people in the US and Australia have hereditary haemochromatosis. It is due to a mutation in a gene called HFE and has autosomal recessive inheritance. Iron overload can also be acquired by receiving numerous blood transfusions, getting iron shots or injections, or consuming high levels of supplemental iron. Iron overload can occur in sickle cell disease, thalassaemia, X-linked sideroblastic anaemia, enzyme deficiencies (pyruvate kinase; glucose-6-phosphate dehydrogenase) and very rare protein transport disorders aceruloplasminaemia and atransferrinaemia.
Nutritional Composition of the Main Edible Algae
Published in Leonel Pereira, Therapeutic and Nutritional Uses of Algae, 2018
Homeostatic mechanisms are very important for the prevention of accumulation of excess Fe, which is believed to generate oxidative stress by catalysis of a variety of chemical reactions involving free radicals, which could result in cell damage (Pietrangelo 2002, Puntarulo 2005). Excess Fe accumulation has been suggested to promote cancer and increase cardio-vascular risks (Martínez-Navarrete et al. 2002). Iron overload may be observed in some cases, including an excessive dietary Fe intake, inherited diseases, e.g., idiopathic haemochromatosis, congenital atransferrinemia, or the medical treatment of thalassemia (Fontecave and Pierre 1993, Shamsian et al. 2009).
Iron Metabolism: Iron Transport and Cellular Uptake Mechanisms
Published in Bo Lönnerdal, Iron Metabolism in Infants, 2020
The importance of transferrin for iron exchange is perhaps best explained in the very rare genetic disorder known as atransferrinemia.250–254 The paradoxical situation in atransferrinemia is that there is, on the one hand, generalized iron overload and, on the other hand, a profound and refractory hypochromic, microcytic anemia due to an inadequate iron supply.251,253 Without transferrin it is difficult to get iron into cells for the biosynthesis of hemoglobin and it is equally difficult to regulate the absorption of iron.2 In the presence of transferrin, the most relevant biological expression of iron supply is the transferrin saturation because of the direct relationship between saturation and diferric iron and the much greater capacity of diferric transferrin to deliver iron to tissues255,256 (Figure 10). Normal saturation cycles between 35% in the morning and 20% at night, but occasionally will go as low as 15% and as high as 50% or even higher. Such fluctuations are not surprising in view of the small amount of plasma iron in relation to the amount of iron required by tissues. Similar saturation levels are seen from adolescence to old age. In the presence of basal erythropoiesis, a saturation of 16% or more delivers an adequate amount of iron for tissue requirements. When the transferrin saturation is less than 16%, hemoglobin synthesis can no longer be sustained at a basal level, causing iron-deficient erythropoiesis. The fall in percent saturation may be due to either an absolute deficiency of iron or an inflammatory state; however, the patterns of plasma iron and total iron-binding capacity are usually quite different in these two conditions. Patients with absolute iron deficiency tend to have a higher than normal TIBC (that is, transferrin level), while inflammation is associated with a decrease in the total iron-binding capacity. High percent saturation (greater than 60%) is occasionally seen as normal fluctuation, but persistence of this deviation usually signals hepatic disease, abnormal erythropoiesis, or parenchymal iron overload (Figure 11).
A deep dive into future therapies for microcytic anemias and clinical considerations
Published in Expert Review of Hematology, 2023
François Rodrigues, Tereza Coman, Guillemette Fouquet, Francine Côté, Geneviève Courtois, Thiago Trovati Maciel, Olivier Hermine
Approximately 70% of the total body iron (3–5 g in adult humans) is bound to heme in red blood cells [2]. Significant fractions are distributed within the liver hepatocytes (20%) and macrophages (5%). On a daily basis, erythropoiesis requires up to 30 mg of iron, while non-erythroid cell requirements are about 5 mg. The plasma iron pool is only 3–4 mg and thus turns over more than ten times per day to satisfy the daily iron requirements. The iron carrier transferrin is central to iron trafficking. Transferrin not only serves as an iron carrier but also keeps circulating iron in a redox-inactive state. Under physiological conditions, only 30% of transferrin molecules are saturated with Fe3+. A rare genetic cause of microcytic anemia, congenital atransferrinemia, highlights the central role of transferrin as a regulated distributor of iron to erythroid and non-erythroid tissues [3]. Children affected by this condition present microcytic anemia due to inefficient iron delivery to erythroblasts, associated with iron overload in non-erythroid tissues, such as the myocardium, liver, or central nervous system because of free iron toxicity.