36 Non-Megaloblastic Macrocytic Anemia
Michelle To and Valentin Villatoro
A group of anemias that present with macrocytes without megaloblastic features. Most often, non-megaloblastic macrocytic anemias are caused by: alcoholism, liver disease, bone marrow failure, and myelodysplastic syndromes (MDS).1,2
Chronic and heavy consumption of alcohol can lead to macrocytosis due to a variety of effects it has in erythrocyte development. Alcohol can not only interfere with folate metabolism but also is also directly toxic on bone marrow precursors. 1,3
Liver disease is commonly associated with alcoholism and it is thought that macrocytosis is caused by an increase in cholesterol and lipids in the red blood cell membrane.3
Note: Additional information about bone marrow failure and MDS will be discussed in later chapters.
Laboratory Features: 1-4
*MCV: usually 100-110 fL
(MCV is rarely >110 fL)
*RETIC: Increased (if hemolytic anemia is present)
*NO hypersegmented neutrophils
Nomorcellular or hypercellular
*Megaloblastic features are absent in precursors
Iron Studies (Liver Disease):
Serum Iron: Decreased to Normal
Transferrin Saturation: Normal to Increased
Liver enzyme tests
*Features that differentiate megaloblastic from non-megaloblastic anemias
1. Hubbard J, Robinson S. Megaloblastic and nonmegaloblastic macrocytic anemias. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 277-301.
2. Nagao T, Hirokawa M. Diagnosis and treatment of macrocytic anemias in adults. J Gen Fam Med [Internet]. 2017 Oct 13 [cited 2018 Jun 25];18(5):200–4. Available from: http://doi.wiley.com/10.1002/jgf2.31
3. Taghizadeh M. Megaloblastic anemias. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 138-55.
4. Goossen LH. Anemias caused by defects of DNA metabolism. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 314-30.