Merck Manual

Please confirm that you are a health care professional

honeypot link

Overview of Decreased Erythropoiesis


Evan M. Braunstein

, MD, PhD, Johns Hopkins School of Medicine

Last full review/revision Mar 2020| Content last modified Mar 2020
Click here for Patient Education

Anemia, a decrease in the number of red blood cells (RBCs), hemoglobin (Hb) content, or hematocrit (Hct), can result from decreased RBC production (erythropoiesis), increased RBC destruction, blood loss, or a combination of these factors. (See also Approach to the Patient with Anemia.)

Anemias due to decreased erythropoiesis (termed hypoproliferative anemias) are recognized by a reticulocyte count that is inappropriately low for the degree of the anemia.

The RBC indices, mainly the mean corpuscular volume (MCV), can narrow the differential diagnosis of deficient erythropoiesis and help determine what further testing is necessary.

Microcytic anemias result from deficient or defective heme or globin synthesis. Microcytic anemias include

Patients with a microcytic anemia typically require evaluation of iron stores.

Normocytic anemias are characterized by a normal RBC distribution width (RDW) and normochromic indices. The two most common causes are

Acquired primary bone marrow disorders such as aplastic anemia, pure red cell aplasia, and myelodysplastic syndrome (MDS) can also manifest with a normocytic anemia.

Macrocytic anemias can be caused by impaired DNA synthesis leading to megaloblastosis, as occurs with .

Other causes of macrocytic anemia include

Some patients with hypothyroidism have macrocytic RBC indices, including some without anemia.

Anemias can have variable findings on the peripheral smear. The anemia of chronic disease may be microcytic or normocytic. Anemias due to myelodysplastic syndromes may be normocytic, macrocytic, or even microcytic. Anemias due to endocrine disorders (such as hypothyroidism) or elemental deficiencies (eg, copper deficiency, zinc deficiency) can have variable manifestations, including a normocytic or macrocytic anemia.

Treatment of deficient RBC production depends on the cause.

Drugs Mentioned In This Article

Drug Name Select Trade
Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read

Also of Interest