Aplastic anemia: causes, symptoms, diagnosis and treatment

Mechanism and key features

The basic lesion in aplastic anemia is a hypocellular marrow, where normal hematopoietic tissue is replaced by fat and stroma. Because the marrow cannot supply circulating cells, patients develop anemia (fatigue, breathlessness), neutropenia (recurrent or severe infections) and thrombocytopenia (easy bruising, mucosal bleeding). Laboratory testing typically shows low hemoglobin, low absolute neutrophil count, and low platelets.

Causes and risk factors

Causes include immune‑mediated destruction of hematopoietic stem cells, exposure to certain drugs or chemicals (for example some antibiotics, chemotherapy agents, and benzene), radiation, and viral infections. A subset of cases is inherited (for example Fanconi anemia and other bone marrow failure syndromes). Many cases are classified as idiopathic when no clear trigger is identified.

Diagnosis and important distinctions

Diagnosis is made by blood counts and bone marrow examination that demonstrate a markedly hypocellular marrow without malignant infiltration. It must be distinguished from other causes of cytopenias such as myelodysplastic syndromes, leukemia, marrow infiltration by cancer, and vitamin deficiencies. Careful history, medication review and targeted tests help exclude reversible causes.

Treatment and prognosis

Treatment depends on age, severity and cause. Options include supportive care (transfusions, infection control), immunosuppressive therapy (antithymocyte globulin with cyclosporine), and hematopoietic stem cell transplantation for eligible patients. Growth factors and antibiotic prophylaxis may be used selectively. With appropriate therapy many patients recover or achieve durable partial responses, but severe untreated aplastic anemia carries a high risk of fatal infections or bleeding. Long‑term follow up is needed because of relapse risk and potential late complications.

Clinical importance

• Aplastic anemia affects all ages and requires timely diagnosis because early treatment improves outcomes.
• Management frequently involves a multidisciplinary team including hematology, infectious disease and transplant specialists.
• Research continues into better immunomodulatory drugs, stem cell sources and gene therapy for inherited forms.

For more detailed clinical guidelines and resources consult specialist hematology references or professional societies. Bone marrow and blood cell physiology remain central to understanding and treating this condition.