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# Aplastic anaemia

The bone marrow stops making enough blood cells, so red cells, white cells and platelets all fall; in most cases the immune system attacks the marrow.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Sternum](https://durgical.com/en/anatomy/sternum/)
- [Hip bone](https://durgical.com/en/anatomy/hip-bone/)
- [Liver](https://durgical.com/en/anatomy/liver/)

## In the clinical exam

- [Anemia syndrome](https://durgical.com/en/clinical-exam/anemia-syndrome/)

## Why it happens

- [Ionizing radiation injury](https://durgical.com/en/general-pathology/ionizing-radiation-injury/)
- [Injury by therapeutic drugs: the classic examples](https://durgical.com/en/general-pathology/injury-by-therapeutic-drugs-the-classic-examples/)
- [Hematopoiesis](https://durgical.com/en/physiology/hematopoiesis/)
- [Hematopoiesis and bone marrow](https://durgical.com/en/histology/hematopoiesis-and-bone-marrow/)
- [Stem cells and tissue renewal: labile, stable and permanent tissues](https://durgical.com/en/histology/stem-cells-and-tissue-renewal-labile-stable-and-permanent-tissues/)

## What it is

A rare bone marrow failure in which the blood-forming stem cells are lost and the marrow becomes empty and replaced by fat, causing pancytopenia without leukaemia or fibrosis. Most acquired cases are immune-mediated. Fanconi anaemia is the classic inherited form.

## Who gets it

About two new cases per million people a year in Europe and North America, two to three times higher in Asia; it peaks in adolescents and young adults and again after 60. Latin American series report a similar young-adult peak; access to transplantation and immunosuppressive therapy is a key limitation in the region.

## Causes

- Immune-mediated (idiopathic) destruction of stem cells by T lymphocytes, the most common cause
- Drugs and chemicals: chloramphenicol, some anticonvulsants and antithyroid drugs, benzene, insecticides
- Viral: seronegative hepatitis (hepatitis-associated aplastic anaemia), Epstein-Barr virus, HIV
- Radiation and cytotoxic chemotherapy (predictable, dose-related)
- Inherited bone marrow failure syndromes: Fanconi anaemia, dyskeratosis congenita
- Pregnancy and paroxysmal nocturnal haemoglobinuria (overlap)

## Risk factors

- Exposure to benzene, solvents or pesticides
- Use of drugs linked to marrow toxicity
- Recent hepatitis of unknown cause
- Family history of marrow failure or congenital anomalies

## Pathophysiology

Activated cytotoxic T cells and cytokines (interferon-gamma, TNF) destroy CD34-positive haematopoietic stem cells. With fewer stem cells, all three lines fall: anaemia with low reticulocytes, neutropenia and thrombocytopenia. Fanconi anaemia is a defect in DNA repair genes that causes progressive marrow failure, congenital anomalies (short stature, thumb and [radius](https://durgical.com/en/anatomy/radius/) defects, café-au-lait spots) and a high risk of leukaemia and squamous cancers.

## Classification

- Severity (Camitta criteria): severe if marrow cellularity is under 25% plus two of neutrophils under 0.5 x 10^9/L, platelets under 20 x 10^9/L or very low reticulocytes
- Very severe: as above with neutrophils under 0.2 x 10^9/L
- Non-severe: cytopenias not reaching these limits
- Acquired versus inherited (Fanconi anaemia, telomere disorders)

## Symptoms and signs

- Fatigue, pallor and breathlessness
- Petechiae, bruising, gum bleeding and nosebleeds
- Recurrent or severe infections, mouth ulcers
- No enlargement of the spleen, liver or lymph nodes (their presence suggests another diagnosis)
- In Fanconi anaemia: short stature, thumb or forearm anomalies, [skin](https://durgical.com/en/anatomy/skin/) pigment changes

## Red flags

- Fever with neutropenia (oncologic-type emergency)
- Active bleeding or headache with very low platelets
- Severe anaemia with [chest](https://durgical.com/en/anatomy/region/chest/) pain or heart failure
- Blasts on the blood film, which point to leukaemia rather than aplasia

## Diagnosis

**Clinical**
Pancytopenia without organomegaly in a young adult or child; take a careful history of drugs, chemicals, recent hepatitis and family history, and look for congenital anomalies.

**Tests**
Complete blood count with low reticulocytes and a blood film without blasts or dysplasia. The key test is a bone marrow biopsy showing a hypocellular, fat-filled marrow without abnormal cells or fibrosis. Flow cytometry for a PNH clone, chromosome breakage test (diepoxybutane or mitomycin C) for Fanconi anaemia in young patients, vitamin B12 and folate, [liver](https://durgical.com/en/anatomy/liver/) tests, viral serologies and HLA typing of patient and siblings early for transplantation.

**Imaging**
Not routinely needed; ultrasound of the [abdomen](https://durgical.com/en/anatomy/region/abdomen/) to confirm normal [spleen](https://durgical.com/en/anatomy/spleen/) size and imaging of [kidneys](https://durgical.com/en/anatomy/kidney/) and limbs if Fanconi anaemia is suspected.

## Differential diagnosis

- Hypoplastic myelodysplastic syndrome
- Acute leukaemia (especially hypocellular ALL in children)
- Paroxysmal nocturnal haemoglobinuria
- Megaloblastic anaemia (B12 or folate deficiency)
- Marrow infiltration or fibrosis (lymphoma, myelofibrosis, tuberculosis)
- Hypersplenism and severe infections causing pancytopenia

## Goal of treatment

Restore blood production with transplantation or immunosuppression, while preventing infection and bleeding with supportive care.

## Treatment

**Procedure**
Allogeneic haematopoietic stem cell transplantation from a matched sibling is first-line for severe disease in young patients and can be curative.

**Medical**
Immunosuppressive therapy with antithymocyte globulin plus ciclosporin, usually with eltrombopag (a thrombopoietin receptor agonist), for patients without a suitable donor or who are older.

**Acute**
Supportive care: leucodepleted and irradiated blood products used sparingly before transplant, platelet transfusion for bleeding or very low counts, and empirical broad-spectrum antibiotics for febrile neutropenia.

**Conservative**
Stop any suspected drug or toxic exposure; iron chelation if many transfusions have been given.

**Follow-up**
Nursing priorities: neutropenic precautions and hand hygiene, bleeding precautions (soft toothbrush, no injections into muscle), temperature monitoring, transfusion safety, and long-term surveillance for relapse, PNH, myelodysplasia or leukaemia.

## Drugs for this condition

- [Eltrombopag](https://durgical.com/en/pharmacology/eltrombopag/)

## Complications

- Severe bacterial and invasive fungal infections
- Haemorrhage, including intracranial bleeding
- Transfusion complications: alloimmunisation, iron overload
- Clonal evolution to PNH, myelodysplastic syndrome or acute myeloid leukaemia
- Graft-versus-host disease after transplantation

## Prognosis

Untreated severe aplastic anaemia is usually fatal. Transplantation from a matched sibling in young patients and modern immunosuppressive therapy give long-term survival for most patients, though relapse and clonal evolution can occur after immunosuppression.

## Prevention

- Avoid unnecessary exposure to benzene and pesticides and use protective equipment at work
- Monitor blood counts when using drugs known to suppress the marrow

## Test yourself

Think of the answer, then tap the question to see it.

## What does the bone marrow biopsy show in aplastic anaemia?

A hypocellular marrow replaced by fat, without abnormal or malignant cells.

## Which antibiotic is classically linked to aplastic anaemia?

Chloramphenicol.

## What is first-line treatment for severe aplastic anaemia in a young patient with a matched sibling?

Allogeneic haematopoietic stem cell transplantation.

## Which inherited disorder combines marrow failure, thumb and radius anomalies and DNA repair defects?

Fanconi anaemia, confirmed with a chromosome breakage test.

## Why does splenomegaly argue against aplastic anaemia?

Aplastic anaemia is marrow failure without infiltration; an enlarged spleen suggests leukaemia, lymphoma, myelofibrosis or hypersplenism.

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## Related conditions

- [Acute leukaemia (AML and ALL)](https://durgical.com/en/conditions/acute-leukaemia/)
- [Myelodysplastic syndromes](https://durgical.com/en/conditions/myelodysplastic-syndromes/)
- [Paroxysmal nocturnal haemoglobinuria](https://durgical.com/en/conditions/paroxysmal-nocturnal-haemoglobinuria/)
- [Viral hepatitis](https://durgical.com/en/conditions/viral-hepatitis/)
- [Febrile neutropenia](https://durgical.com/en/conditions/febrile-neutropenia/)
- [Immune thrombocytopenia (ITP)](https://durgical.com/en/conditions/immune-thrombocytopenia/)
- [Megaloblastic anaemia (B12 or folate deficiency)](https://durgical.com/en/conditions/megaloblastic-anaemia/)
- [Transfusion reactions](https://durgical.com/en/conditions/transfusion-reactions/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Aplastic anemia](https://medlineplus.gov/ency/article/000554.htm) (MedlinePlus (U.S. National Library of Medicine), 2026); [Fanconi anemia](https://medlineplus.gov/genetics/condition/fanconi-anemia/) (MedlinePlus (U.S. National Library of Medicine), 2025).

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Source: https://durgical.com/en/conditions/aplastic-anaemia/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/aplastic-anaemia/