5.2: Non-Megaloblastic Macrocytic Anemia

Cause(s):

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

CBC: PLT: Decreased *MCV: usually 100-110 fL (MCV is rarely >110 fL) *RETIC: Increased (if hemolytic anemia is present)	PBS: *Round Macrocytes Target cells *NO hypersegmented neutrophils	BM: Nomorcellular or hypercellular Erythroid hyperplasia *Megaloblastic features are absent in precursors
Iron Studies (Liver Disease): Serum Iron: Decreased to Normal Ferritin: Increased Transferrin: Normal Transferrin Saturation: Normal to Increased	Other Tests: Liver enzyme tests
*Features that differentiate megaloblastic from non-megaloblastic anemias

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References:

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.

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