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Revista Argentina de Hematología

Abstract

Volumen:    21    # Number : XXIII Congreso Argentino de Hematología

Publication Date :    NOVIEMBRE    Year:    2017

   CONFERENCIA NACIONAL Dr. Miguel Ángel Etcheverry

Iron overload

Authors: Chiappe G

Abstract: The organism in whole and each cell in particular regulate iron disposal by income, not by outcome. Only three cells: enterocytes, macrophages and hepatocytes express ferroportin, the only known iron exporter, on their vascular surface. All the other cells, as well as the body itself, are incapable of eliminating any iron excess. Each cell regulates iron admission through the expression on its surface of transferrin receptor-1 and divalent metal transporter-1, according to its own iron requirements, expressed through iron responsive proteins-1 and 2 (local regulation). Systemic regulation of iron intake is managed by hepcidin, whose synthesis, primarily in hepatocytes, is controlled by plasmatic and hepatocyte iron content, inflammation and degree of erythropoiesis. Hepcidin blocks iron income into plasma through ferroportin internalization and degradation. Systemic iron overload must be firstly differentiated from local iron misdistribution, which may or may not be accompanied by iron overload. Systemic iron overload may be primary, when there is a defect in the synthesis of proteins involved in iron metabolism, or secondary, when the iron enters in excess into the organism through enteral (“physiological” hepcidin underexpression secondary to hereditary or acquired pathologies) or parenteral (transfusions) ways. Secondary iron overload, often underdiagnosed, is much more frequent than primary iron overload, sometimes incorrectly overdiagnosed. Hereditary hemochromatosis is, by far, the most frequent primary iron overload syndrome, followed by a perhaps not infrequent ferroportin disease. Among hemochromatosic syndromes, HFE hemochromatosis is the most common, with C282Y mutation as the most important and H63D mutation as the most frequent. Diagnosis must be supported on two pillars: an important genetic background (homozygous HFE C282Y or double heterozygous HFE C282Y/H63D) and a coincident hemochromatosic profile with early transferrin saturation and subsequent plasmatic ferritin elevation, much higher iron deposition in liver than in spleen on nuclear magnetic resonance, and more parenchymal (hepatocytes) than macrophage (Kupffer cells) iron accumulation on liver biopsy. This adult hemochromatosis has a slow progression (years, decades) and a low penetrance, as only about half of HFE C282Y homozygous patients will eventually develop any iron profile alteration (stage 1) and perhaps less than a quarter will even express clinical manifestations (stage 2). Therefore it’s important the routine control of transferrin saturation every 5-10 years from adolescence on in order to detect early iron metabolism alterations and correct them before the appearance of clinical complications. Treatment of hereditary hemochromatosis requires the elimination of iron excess through periodical phlebotomies (or erythrocyte apheresis in severe cases, eventually with the addition of erythropoietin). There is no need to identify HFE hemochromatosic patients at stage 0 (genetic survey), but undoubtedly at stage 1 in order to avoid any progression to stage 2.

Key words: iron overload, hemochromatosis, hyperferritinemia.

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SOCIEDAD ARGENTINA DE HEMATOLOGÍA
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