Transfusion-dependent anemia is a form of anemia characterized by the need for continuous blood transfusion. It is a condition that results from various diseases, and is associated with decreased survival rates. Regular transfusion is required to reduce the symptoms of anemia by increasing functional red blood cells and hemoglobin count. Symptoms may vary based on the severity of the condition and the most common symptom is fatigue. Various diseases can lead to transfusion-dependent anemia, most notably myelodysplastic syndromes (MDS) and thalassemia. Due to the number of diseases that can cause transfusion-dependent anemia, diagnosing it is more complicated. Transfusion dependence occurs when an average of more than 2 units of blood transfused every 28 days is required over a period of at least 3 months. Myelodysplastic syndromes is often only diagnosed when patients become anemic, and transfusion-dependent thalassemia is diagnosed based on gene mutations. Screening for heterozygosity in the thalassemia gene is an option for early detection.
The transfusions itself alleviates the symptoms of anemia, and are used to treat the disease that causes transfusion dependence. The recommended restrictive threshold for blood transfusion is a hemoglobin level of 7 to 8 g/dL, while a more liberal threshold is set at 9 to 10 g/dL. However, more evidence may be required to establish a consensus on the threshold and a personalized approach may be more useful. The main complication of transfusion dependence is iron overloading, which can damage the liver, heart, bone tissue and endocrine glands. Iron chelation therapy is used to treat iron overload and common iron chelators used are deferoxamine, deferiprone and deferasirox. Due to the complications of transfusions dependency, it may be more ideal to directly treat the cause of anemia if possible. However this might not be suitable for all patients, and some may still rely on frequent blood transfusions for survival. While transfusion-dependent anemia has a poor prognosis, advancement in iron chelation therapy may help increase survival rates.
Signs and symptoms
See more: Anemia
When transfusion dependent patients do not receive their transfusion, symptoms of anemia may arise. The most common symptom that patients experience is fatigue, and other symptoms include shortness of breath, dizziness and heart palpitations. Symptoms may vary depending on the severity of the disease. The use of blood transfusions can ease some of these symptoms by replenishing the blood cells and maintain sufficient hemoglobin levels, however, the goal to improve the overall oxygen-carrying capacity has conflicting results.
Causes
There are numerous causes for transfusion dependent anemia, typically due to diseases affecting the blood.
Thalassemia
Alpha-thalassemia
Hemoglobin Barts hydrops fetalis is the most severe form of alpha-thalassemia, and individuals with this disease have severe anemia during the fetal stage of development. It has been considered as fatal until advances in treatment were made. Patients that survive hemoglobin Barts hydrops fetalis will become transfusion dependent.
Beta-thalassemia
Bata-thalassemia causes decreased functional hemoglobin production, and blood transfusions can be given to maintain a sufficient hemoglobin level. Patients with beta thalassemia major are more affected and are recommended to receive transfusion throughout their lives.
Myelodysplastic syndromes (MDS) Myelodysplastic syndromes are disorders where defective blood cells are produced by an abnormal bone marrow, resulting in anemia. Severe cases may require ongoing transfusions, and around 70% of people with myelodysplastic syndromes become transfusion dependent at some point. Patients who are initially considered to be lower-risk may experience disease progression as a result of becoming dependent on blood transfusion when they become increasingly unresponsive to alternative treatments.
Diagnosis
Diagnosis of transfusion dependent anemia is challenging because this anemia is caused by multiple diseases. Therefore, other than diagnosing anemias that require transfusion, diagnosis for the two main causes (beta-thalassemia and myelodysplastic syndromes) of transfusion dependent anemia is also important.