What is the transfusion threshold for anemia (low red blood cell count)?

From the Guidelines

Transfusion for anemia is generally recommended when hemoglobin levels fall below 7-8 g/dL in stable, non-bleeding patients, including those with cardiovascular disease, as this restrictive strategy has been shown to reduce complications associated with unnecessary transfusions 1.

Key Considerations

• The American Association of Blood Banks (AABB) and the American College of Physicians (ACP) recommend a restrictive transfusion strategy for hospitalized patients, including those with coronary heart disease, with a trigger hemoglobin threshold of 7-8 g/dL 1.
• This approach is based on high-quality evidence that suggests liberal transfusion strategies do not improve outcomes and may increase the risk of complications, such as infection, transfusion reactions, and volume overload.
• For patients with acute coronary syndrome, the evidence is less clear, but a restrictive strategy is still recommended, with consideration of transfusion for patients with symptoms or a hemoglobin level of 8 g/dL or less 1.

Transfusion Thresholds

• Stable, non-bleeding patients without cardiovascular disease: 7 g/dL 1
• Patients with cardiovascular disease or active bleeding: 8 g/dL 1
• Acute coronary syndrome: consider transfusion at hemoglobin levels below 8 g/dL, but the evidence is uncertain 1

Administration of Transfusions

• Administer one unit of packed red blood cells at a time, then reassess the patient's hemoglobin level and clinical status before giving additional units.
• The goal is not to normalize hemoglobin but to alleviate symptoms and maintain adequate oxygen delivery to tissues.

Underlying Cause of Anemia

• For chronic anemia, addressing the underlying cause (such as iron deficiency, B12 deficiency, or chronic disease) is preferable to repeated transfusions 1.

From the Research

Transfusion Threshold for Anemia

• The transfusion threshold for anemia is a topic of ongoing debate, with various studies suggesting different hemoglobin levels for transfusion 2, 3, 4.
• A restrictive transfusion strategy of 7 to 8 g/dL is considered as safe as a liberal transfusion strategy of 9 to 10 g/dL in many clinical settings 2, 3.
• However, evidence is lacking for subgroups of patients, including those with preexisting coronary artery disease, acute myocardial infarction, congestive heart failure, and myelodysplastic neoplasms 2.
• The American Association of Blood Banks guidelines recommend a restrictive threshold of 7 g/dL, which is supported by multiple meta-analyses in settings such as gastrointestinal bleeding, sepsis, critical illness, and trauma 3.
• The choice to transfuse should be guided by patient symptoms and preferences in conjunction with the patient's hemoglobin concentration, as well as evaluation and management of the etiology of the anemia 2, 3.

Patient-Specific Considerations

• Patients with active ischemia in acute coronary syndrome and neurologic injury require additional study to determine the optimal transfusion threshold 3.
• The physician must consider the patient's hemodynamic status, comorbidities, risks and benefits of transfusion, and clinical setting in determining the need for transfusion 3.
• Iron-restricted erythropoiesis is a common cause of anemia severe enough to be considered for red blood cell transfusion, and intravenous iron therapy is generally the treatment of choice for absolute iron deficiency in patients with complex medical disorders 2.

Alternative Treatments

• Erythropoiesis-stimulating agents (ESAs) and iron therapy may reduce the need for red blood cell transfusion in surgical patients, although the optimal treatment strategy remains to be established 5, 6.
• Preoperative iron supplementation with or without ESAs may reduce red blood cell utilization in patients with preoperative anemia undergoing elective surgery, although the certainty of evidence varies 6.