Should hydroxyurea (Hydrea) be stopped in patients with low hemoglobin (anemia) who are planned for blood transfusion?

Management of Hydroxyurea in Patients with Low Hemoglobin Requiring Blood Transfusion

Hydroxyurea should be temporarily discontinued in patients with low hemoglobin who are planned for blood transfusion to avoid potential complications from myelosuppression and to allow for accurate assessment of transfusion response. 1

Rationale for Discontinuing Hydroxyurea

• Hydroxyurea causes myelosuppression, with anemia being one of its known hematologic effects, which could worsen pre-existing low hemoglobin levels 1
• The FDA label specifically warns that "treatment with hydroxyurea should not be initiated if bone marrow function is markedly depressed" and recommends to "provide supportive care and modify dose or discontinue hydroxyurea as needed" 1
• Recovery from myelosuppression is usually rapid when hydroxyurea therapy is interrupted 1
• Temporary discontinuation allows for more accurate assessment of the patient's response to transfusion without the confounding effect of ongoing myelosuppression 1

Monitoring and Management Approach

Before Transfusion:

• Evaluate complete hematologic status prior to transfusion to establish baseline values 1
• Temporarily discontinue hydroxyurea to prevent additive myelosuppressive effects 1
• For patients with sickle cell disease (SCD), be aware that a conservative hemoglobin threshold is advised, not exceeding 10 g/dL (hematocrit of 30%) to reduce the risk of vaso-occlusion–related complications 2

During and After Transfusion:

• Monitor hemoglobin levels closely during and after transfusion 2
• For patients with SCD, aim for post-transfusion hemoglobin levels of 10-11 g/dL to minimize complications 2
• Consider exchange transfusion rather than simple transfusion for patients with hemoglobin levels greater than 9-10 g/dL 2

Resuming Hydroxyurea:

• Resume hydroxyurea only after hemoglobin has stabilized following transfusion 1
• Consider dose reduction if there is evidence of persistent bone marrow suppression 1
• For patients with renal impairment (creatinine clearance <60 mL/min), reduce the dose by 50% when restarting 1

Special Considerations in Sickle Cell Disease

• For SCD patients with chronic kidney disease and worsening anemia, combination therapy with hydroxyurea and erythropoiesis-stimulating agents may be considered after transfusion and stabilization 2, 3
• When using combination therapy, maintain hemoglobin levels below 10 g/dL to reduce the risk of vaso-occlusive complications 2, 3
• Optimizing adherence to hydroxyurea therapy may help maximize fetal hemoglobin responses in SCD patients 2

Potential Complications and Pitfalls

• Hemolytic anemia: Patients who develop acute jaundice or hematuria with worsening anemia should be evaluated for hemolysis; if confirmed, hydroxyurea should be discontinued 1
• Rebound effect: Abrupt discontinuation of hydroxyurea may lead to worsening of SCD symptoms in some patients 4
• Monitoring for recovery: Ensure adequate recovery from myelosuppression before resuming hydroxyurea, as recovery is typically rapid when therapy is interrupted 1
• Drug interactions: Be aware of potential interactions between hydroxyurea and other medications that may affect bone marrow function 1

By temporarily discontinuing hydroxyurea in patients with low hemoglobin requiring blood transfusion, clinicians can minimize the risk of worsening anemia and allow for more accurate assessment of the patient's response to transfusion therapy.