A number of conditions may be associated with microcytic anemia. While iron deficiency, anemia of chronic disease and thalassemia explain most cases, less common causes do occur.


Iron deficiency (associated with high RDW and low MCH):

(1) inadequate intake

(2) increased blood loss

(3) malabsorption (celiac disease, Crohn's disease, etc)

(4) hereditary defect in iron transport or utilization (atransferrinemia, other)

(5) autoantibody against the transferrin receptor



(1) alpha or beta thalassemia

(2) sickle-thalassemia

(3) hemoglobin E


Anemia of chronic disease


Hereditary sideroblastic anemia

(1) X-linked

(2) autosomal recessive

(3) associated with mitochondrial DNA deletion or mutation


Premalignant or malignant disease

(1) myelodysplasia (with or without sideroblasts)

(2) therapy-related myeloid neoplasms

(3) Castleman's disease


Other causes of acquired sideroblastic anemia:

(1) lead poisoning

(2) arsenic poisoning

(3) aluminum poisoning

(4) copper deficiency

(5) alcohol

(6) drugs: isoniazid (INH), chloramphenicol, cycloserine, penicillamine, azathioprine


Associated with mitochondrial DNA deletions or mutations:

(1) Pearson's marrow-pancreas syndrome


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