Susceptometric avaliation of chelation with deferoxamine

Avaliação susceptométrica da quelação com deferoxamina

CARTA AO EDITOR LETTER TO EDITOR

Susceptometric avaliation of chelation with deferoxamine

Avaliação susceptométrica da quelação com deferoxamina

Ivan L. Angulo^I; Antonio A. Carneiro^II; Oswaldo Baffa^III; Dimas T. Covas^IV

^IAssessor médico da Fundação Hemocentro de Ribeirão Preto

^IIDocente Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto da USP

^IIILivre-docente. Professor titular, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto da USP

^IVLivre-docente. Diretor-presidente da Fundação Hemocentro de Ribeirão Preto e docente do Departamento de Clínica Médica da Faculdade de Medicina de Ribeirão Preto da USP

^{Correspondence}

RESUMO

Em pacientes com anemias crônicas a sobrecarga de ferro transfusional causa lesões orgânicas importantes. A quelação do ferro é crucial para a sobrevida e qualidade de vida. A quantidade de ferro removida pela deferoxamina intra-venosa é desconhecida. O ferro hepático é a melhor medida da eficácia da quelação. A susceptometria permite avaliação não invasiva, mas é dispendiosa e disponível em poucos locais. Não há nenhum destes dispositivo na América Latina.

Palavras-chave: Sobrecarga de ferro; deferoxamina; susceptometria magnética; SQUID.

To Editor

Transfusional iron loading causes significant organ damage in patients with congenital or chronic acquired anemias. Iron chelation is therefore essential for a better quality of life and longevity with deferoxamine (DFO) being the most widely used drug. The amount of iron removed with intravenous (IV) infusions of DFO is unknown, especially in patients with heavy iron accumulation. Hepatic iron has a positive and linear correlation with total body iron and is the best predictor of the efficacy of chelation. Susceptometry is an excellent non-invasive measurement tool, but is expensive and is available in only a few centers. There are no susceptometry apparatuses in Latin America.

This study involved 9 male and 5 female patients with ages between 11 and 75 years old. Eight patients had beta thalassemia major, 3 had sickle cell disease and 3 had chronic acquired anemias receiving regular red cell transfusions for more than one year (19 or more transfusions). All individuals had heavy iron loading (serum ferritin above 2500 mg/L). Doses of 35 to 100 mg/kg of DFO were infused intravenously during 8 hours a day for 5 days weekly. Two thalassemic patients received infusions on a regular basis for hemosiderotic heart failure, but only one infusion was analyzed per patient. Hepatic susceptometry was performed everyday just before the infusion.

Iron measurement was obtained in milligrams per gram of wet tissue (mg/gwt). Iron loading remained unchanged on only one occasion, was reduced on six but increased on seven.

Intravenous infusions of DFO changed hepatic iron deposits in all but one case. Surprisingly, iron concentrations were increased on the majority of occasions, suggesting a relocation of iron stores in the organ. Prolonged infusions are desirable as it seems that all patients have their own pattern of response and a reduction may only be expected after some iron is mobilized. This is the first time in Latin America that hepatic iron was evaluated by susceptometry during IV infusions, and showed the efficacy of this form of chelation, even in a short-term infusion program.

Recebido: 14/04/2008

Aceito: 09/05/2008

Avaliação: Editor e dois revisores externos

Conflito de interesse: não declarado

• 1. Olivieri N, Brittenham G. M. Iron-chelating therapy and the treatment of thalassemia. Blood 1997;89(3):739-61.
• 2. Carneiro AAO, Fernandes JP, Zago MA, Covas DT, Ângulo IL, Baffa O. An alternating current superconductor susceptometric system to evaluate liver iron overload. Rev Sci Instrum 2003;75(6):3098-103.
• 3. Carneiro AAO, Fernandes JP, Araújo DB, Elias Jr. J, Martinelli A, Covas DT et al. Liver iron concentration evaluated by two magnetic methods: Magnetic Resonance Imaging and Magnetic Susceptometry. Magn Reson Med. 2005;54:122-8.

Correspondence:

Ivan de Lucena Angulo

Centro Regional de Hemoterapia do Hospital das Clínicas da

Faculdade de Medicina de Ribeirão Preto da USP

Fundação Hemocentro de Ribeirão Preto

Rua Tenente Catão Roxo, 2501 - Monte Alegre

14051-140 - Ribeirão Preto-SP - Brasil

Publication Dates

• Publication in this collection
  28 Oct 2008
• Date of issue
  Aug 2008