Abstract

CANO-CASTELLANOS, Raúl; LOPEZ-SANTIAGO, Norma  and  PIEDRAS, Josefa. Iron overload in pediatric patients. Bol. Med. Hosp. Infant. Mex. [online]. 2009, vol.66, n.6, pp.481-491. ISSN 1665-1146.

In pediatrics, chronic genetic anemias such as sickle cell disease, thalassemic syndromes and, to a lesser degree, aplastic anemia, pure red cell aplasia, myelodysplastic syndromes and dyserythropoietic syndromes, are characterized by high transfusional requirements and, consequently, a potential risk to develop iron overload. Iron transfusional loading is initially processed by macrophages after the breakdown of senescent erythrocytes and the iron released to plasma transferrin. This transfusional iron load can saturate the transferrin and result in the emergency of toxic "plasma nontransferrin bound iron" that is taken up by the parenchymal hepatic cells and stored as ferritin and hemosiderin. The iron can be reduced from ferric (Fe³⁺) to ferrous (Fe²⁺) ions and catalyze the formation of free hydroxyl radicals (highly reactive) that may produce oxidative damage that may also affect lipids, proteins and DNA molecules and finally result in cellular death and/or fibrosis. Transferrin saturation index and serum ferritin serial measurements have shown to be simple and reliable techniques for efficiently evaluating iron overload and chelation therapy. The SQUID (Superconducting Quantum Interference Device) constitutes a noninvasive method for evaluating iron overload; however, this device is not available in México and only five medical centers worldwide have this equipment. Magnetic resonance imaging can be used to evaluate iron load in liver, heart, and pancreas and may replace invasive procedures such as heart or hepatic biopsies. Deferoxamine, deferiprone and deferasirox are currently used in the treatment of transfusional iron overload. Deferoxamine is infused SC (20-40 mg/kg/day) in a continuous infusion connected to a portable pump for 10-12 h, 5x/week, mainly at night, and IV 20-40 mg/kg/day in a continuous infusion for 1214 h. Intramuscular administration is not recommended due to the low chelation action. A daily dose of 75 mg/ kg of deferiprone is recommended. Deferasirox is safe, orally administered and is as effective as deferoxamine. The effective oral dose is 20-40 mg/kg. Iron balance is obtained with 0.3 mg/kg/day urinary iron excretion in transfusion-dependent patients. Even though there is no conclusive evidence that all anemic polytransfused patients will develop iron overload, it is recommended to carry out integral surveillance programs to establish early iron chelation therapies.

Keywords : anemia; transfusion; iron overload; chelation therapy.

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