Fresher blood products are not necessarily better for patients with beta thalassemia, according to a pair of experts.
Red blood cell units stored less than 2 weeks are ideal, but older units are acceptable, and phenotype matching should take priority over unit age, advisedand both of UCSF Benioff Children’s Hospital Oakland (Calif.). They discussed these and other recommendations for transfusing patients with thalassemia during a hosted by the Centers for Disease Control and Prevention.
Indications for transfusion
Dr. Lal said patients with beta thalassemia major should be transfused if their hemoglobin is less than 7 g/dL on two occasions 2 weeks apart at baseline, or if their hemoglobin is greater than 7 g/dL and they have symptoms of anemia.
Patients with hemoglobin E beta thalassemia major should be transfused only if they have symptoms of anemia.
“The rationale is that, in beta thalassemia major, it is well established that, once the hemoglobin levels fall below 7 g/dL in young children, there is going to be massive bone marrow expansion, and there will be severe symptoms from anemia,” Dr. Lal said. “But the relationship of hemoglobin with symptoms in E beta thalassemia is less precise.”
The symptoms that should prompt transfusion include slowed growth, skeletal facial changes, splenomegaly, symptomatic or moderate to severe extramedullary hematopoiesis, cerebrovascular events, venous thromboembolism, pulmonary hypertension, osteoporotic fracture, and impaired quality of life in adults.
Dr. Lal said physicians should consider a 6-month trial of transfusions if the indication is unclear. He also noted that red cell antigen genotyping should be performed in all patients who may need transfusions.
Dr. Lal said beta thalassemia patients should receive packed red blood cells that are leukoreduced prior to storage. The storage solution can be citrate-phosphate-dextrose solution with adenine (hematocrit 75%) or additive solution (hematocrit 60%).
“It’s important to note that the hematocrit of the two is quite different, and that needs to be inculcated into the decisions on how much volume to transfuse to younger children,” Dr. Lal said.
He noted that units should not be irradiated, as this damages the red cell membrane. And patients with severe allergic reactions should receive washed red blood cells because washing units removes residual donor plasma proteins.
Finally, units should be less than 2 weeks old if possible. Dr. Lal said using fresh units increases the survival of red blood cells post transfusion. However, he and Dr. Vichinsky both stressed that older units are acceptable, and phenotype matching is more important than the age of the unit.
Beta thalassemia patients who do not have preexisting alloantibodies or have transient autoantibodies should be matched to Rh and Kell, according to Dr. Lal.
Patients with preexisting alloantibodies should be matched to Rh, Kell, Duffy, Kidd, S, and the specific alloantibody. Patients with persistent autoantibodies should be matched to Rh, Kell, Duffy, Kidd, S, and any alloantibody.
Patients who start transfusions after 5 years of age should be matched to Rh, Kell, Duffy, Kidd, and S. Pregnant patients should be matched to Rh, Kell, Duffy, Kidd, and S, and units should be cytomegalovirus negative.