Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 627

To lessen isoimmunization, viral infections, and febrile transfusion reactions, leukoreduced and irradiated products are encouraged. In some cases, patients may receive well over 50 units of packed red blood cells. With each unit of blood containing 250 mg of iron, patients may develop iron overload. High levels of iron may lead to secondary haemochromatosis and its resultant adverse hepatic, pancreatic, gonadal, and cardiac effects.⁷⁸ Iron chelation with deferoxamine⁷⁹ may be administered to these patients; however, this therapy is difficult. Deferoxamine only chelates ∼25 mg of iron per day, must be administered subcutaneously, and can lead to chronic skin irritation and cataracts. Two oral iron chelators are now available: deferiprone and deferasirox. Deferiprone reduced hepatic and cardiac iron content in thalassaemia patients, but its utility in MDS is limited by the risk of agranulocytosis, and it is not currently approved in the US.⁸⁰ Deferasirox is administered once daily and is approved for secondary iron overload in transfusion‐dependent anaemias. It has been tested in MDS and found to decrease serum ferritin significantly at one year in heavily transfused MDS patients, but exactly what impact it has on total‐body iron stores or even survival in MDS is unclear.⁸¹ Side effects typically include mild nausea and diarrhoea, and careful surveillance of renal and hepatic function should be done as nephrotoxicity and hepatotoxicity have been described. Furthermore, baseline hearing and vision tests are recommended prior to initiating the drug and yearly thereafter because of the risk of auditory and ophthalmological disturbances.

Several international guidelines on iron chelation for MDS have been published.^82‐85 Many patients with MDS do not live long enough to develop the complications of iron overload; hence iron chelation as a therapy should be reserved for those patients with lower‐risk disease with an expected survival of more than one year, which is fairly consistent across the various guidelines. Once patients have received anywhere from 20 to 50 units of red blood cells and if the serum ferritin is >1000–2500 ng ml⁻¹, the recommendation is to initiate iron chelation therapy.⁸⁰

In addition to requiring periodic red blood cell transfusions, some patients with more advanced MDS may have severe chronic thrombocytopenia with associated bleeding. This can be life‐threatening if significant bleeding occurs in the brain or gastrointestinal tract. Platelet transfusions can be administered but should be given judiciously as many patients become alloimmunized and then fail to respond to subsequent platelet transfusions.⁸⁶ Similarly to red blood cell transfusions, platelets should be irradiated.^86,87