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Am J Med Sci. 2000 Jun;319(6):343-52.

Etiology and diagnostic evaluation of macrocytosis.

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Department of Medicine, Columbia University, College of Physicians and Surgeons, New York, New York, USA.



Elevation of mean cell volume (MCV) is a common clinical problem, but the etiologic spectrum and optimal diagnostic evaluation of macrocytosis are not well defined.


We studied 300 consecutive hospitalized adult patients with MCV values > or = 100 fL. Assessment included complete blood counts, morphologic review, liver function tests, and levels of serum cobalamin (Cbl), methylmalonic acid, and total homocysteine.


The most common cause of macrocytosis was drug therapy, followed by alcohol, liver disease, and reticulocytosis. Megaloblastic hematopoiesis accounted for less than 10% of cases. MCV values > 120 fL were usually caused by Cbl deficiency. Anisocytosis, macro-ovalocytosis, and teardrop erythrocytes were most prominent in megaloblastic hematopoiesis. Elevated levels of serum methylmalonic acid and total homocysteine were useful in the diagnosis of Cbl deficiency.


Drugs and alcohol are the most common causes of macrocytosis in hospitalized patients in a New York City teaching hospital. We have formulated tentative guidelines for the evaluation of high MCV values in this setting.

[Indexed for MEDLINE]

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