In ICD-10, aplastic anemia is classified under category D61, “Other aplastic anemias and other bone marrow failure syndromes.” The most commonly used codes are D61.3 for idiopathic aplastic anemia, D61.1 for drug-induced disease, and D61.9 when the type is not specified. Picking the right code depends on the cause, and that in turn depends on a careful clinical workup.
This guide walks through the D61 codes, how they map onto the real clinical picture, and what clinicians need to document to support them.
What Is Aplastic Anemia?
Aplastic anemia is a rare hematological disorder in which the bone marrow fails to make enough blood cells. The result is pancytopenia: low red cells, low white cells, and low platelets together. Patients become tired and pale, bruise and bleed easily, and are prone to infections.
The marrow in aplastic anemia is not invaded by cancer or scar tissue. Instead, it is hypocellular, meaning the blood-forming tissue has largely been replaced by fat. For background on how normal marrow is organized, see our article on the composition and function of bone marrow.
The ICD-10 D61 Codes at a Glance
The table below lists the codes most relevant to aplastic anemia in ICD-10-CM, the clinical modification used for coding in the United States. The international WHO version shares the same four-character structure but has fewer subdivisions.
| Code | Description | Typical clinical example |
|---|---|---|
| D61.01 | Constitutional (pure) red blood cell aplasia | Diamond-Blackfan anemia |
| D61.09 | Other constitutional aplastic anemia | Fanconi anemia |
| D61.1 | Drug-induced aplastic anemia | Marrow failure after chloramphenicol |
| D61.2 | Aplastic anemia due to other external agents | Benzene or radiation exposure |
| D61.3 | Idiopathic aplastic anemia | Acquired immune-mediated disease with no identified trigger |
| D61.81x | Pancytopenia | Low counts after chemotherapy (D61.810) or other causes |
| D61.82 | Myelophthisis | Marrow replaced by tumor or fibrosis |
| D61.89 | Other specified aplastic anemias and marrow failure syndromes | Specified types not listed elsewhere |
| D61.9 | Aplastic anemia, unspecified | Diagnosis made but type not yet documented |
Two neighboring codes cause frequent confusion. D60 covers acquired pure red cell aplasia, where only the red cell line fails. D64.9, anemia unspecified, should not be used once aplastic anemia has been confirmed.
Matching the Code to the Cause
ICD-10 separates aplastic anemia primarily by etiology, so the documentation needs to say why the marrow failed.
Idiopathic (D61.3)
Most acquired cases have no identifiable trigger and are thought to be driven by the immune system attacking hematopoietic stem cells. This is the group that responds to immunosuppressive therapy, and it is the most frequently used specific code.
Drug-Induced and External Agents (D61.1, D61.2)
When a medication is responsible, D61.1 is used alongside a code identifying the drug and whether it was an adverse effect or poisoning. Chloramphenicol, some anticonvulsants, and gold compounds are classic culprits. Chemicals such as benzene and ionizing radiation fall under D61.2.
Inherited Forms (D61.0x)
Constitutional marrow failure syndromes are coded under D61.0. Fanconi anemia, a DNA-repair disorder, is the best-known example. Telomere biology disorders such as dyskeratosis congenita also belong in this broader group of inherited causes of bone marrow failure.
Coding should never run ahead of the clinical evidence. If the cause is still under investigation, D61.9 is the honest choice until results clarify the picture.
Clinical Workup That Supports the Code
A confident diagnosis, and therefore a precise code, rests on a structured evaluation. The core steps are:
- History: medications, chemical or radiation exposure, recent hepatitis or other viral illness, and family history of blood disorders or early cancers.
- Complete blood count and reticulocyte count: confirms pancytopenia and a low reticulocyte response.
- Blood film: excludes blasts, abnormal cells, or features of another disorder.
- Bone marrow aspirate and trephine biopsy: shows a hypocellular marrow without malignant infiltration or fibrosis.
- Flow cytometry for PNH clones: paroxysmal nocturnal hemoglobinuria frequently coexists with aplastic anemia.
- Cytogenetics and molecular testing: helps separate aplastic anemia from hypoplastic myelodysplastic syndrome.
- Inherited syndrome screening: such as chromosome breakage testing for Fanconi anemia, especially in younger patients.
These tests are what distinguish aplastic anemia from other hematological disorders that share the same blood count pattern.
Severity Grading and Treatment
ICD-10 codes do not capture severity, but severity drives treatment and should be clearly documented in the notes. Disease is graded as severe when the marrow is markedly hypocellular and at least two of the following apply: neutrophils below 0.5 x 10⁹/L, platelets below 20 x 10⁹/L, or a very low reticulocyte count. It is very severe when neutrophils fall below 0.2 x 10⁹/L. Cases not meeting these thresholds are non-severe.
Treatment options include:
- Hematopoietic stem cell transplantation, the only curative option, usually preferred for younger patients with severe disease and a matched sibling donor.
- Immunosuppressive therapy with antithymocyte globulin (ATG) and cyclosporine, often combined with eltrombopag, a thrombopoietin receptor agonist that supports bone marrow function.
- Supportive care with transfusions, infection prevention, and iron chelation when needed.
Key Takeaways
- Aplastic anemia is coded under ICD-10 category D61, subdivided mainly by cause.
- D61.3 is idiopathic aplastic anemia, not a catch-all code for every case.
- Drug-induced disease uses D61.1; external agents such as benzene or radiation use D61.2; inherited forms use D61.0x.
- D61.9 is appropriate when the type has not been determined.
- Severity is not captured in the code but should be documented because it guides treatment.
Frequently Asked Questions
What is the ICD-10 code for aplastic anemia?
Aplastic anemia sits under D61. The code most often used for acquired disease with no known cause is D61.3, idiopathic aplastic anemia, while D61.9 covers cases where the type is unspecified.
Is D61.3 the same as D61.9?
No. D61.3 means the workup was done and no cause was found. D61.9 means aplastic anemia is diagnosed but the type has not been documented.
How is pancytopenia coded differently from aplastic anemia?
Pancytopenia alone describes low counts and uses the D61.81x codes, such as D61.810 after anticancer chemotherapy. Aplastic anemia is a specific diagnosis confirmed by marrow biopsy and should be coded as such once established.
Which code is used for Fanconi anemia?
Fanconi anemia falls under the constitutional aplastic anemia codes, specifically D61.09 in ICD-10-CM. Local coding guidance should always be checked, since national versions differ slightly.
