Rare diseases · Sign or symptom
Macrocytic anemia
HP:0001972
What it means
A type of anemia characterized by increased size of erythrocytes with increased mean corpuscular volume (MCV) and increased mean corpuscular hemoglobin (MCH).
The causes of macrocytosis can be broadly classified as megaloblastic and nonmegaloblastic. Megaloblastic processes are characterized on the peripheral smear by macroovalocytes and hypersegmented neutrophils, which are absent in nonmegaloblastic macrocytic processes. Nonmegaloblastic processes have round macrocytes or macroreticulocytes.
Rare diseases that can present with this14
Common30–79%
9- Autoimmune polyendocrinopathy type 3
- Autoimmune polyendocrinopathy type 4
- Dehydrated hereditary stomatocytosis
- Homocystinuria without methylmalonic aciduria
- Late-onset isolated ACTH deficiency
- Methylcobalamin deficiency type cblE
- Myelodysplastic neoplasm with low blasts
- Myelodysplastic syndrome associated with isolated del(5q) chromosome abnormality
- Shwachman-Diamond syndrome
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Macrocytic anaemia
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.