title: Etiology and diagnostic evaluation of macrocytosis.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Medicine, Columbia University, College of Physicians and Surgeons, New York, New York, USA. savage@cuccfa.ccc.columbia.edu
authors.forename: D G
authors.initials: DG
authors.lastname: Savage
authors.forename: A
authors.initials: A
authors.lastname: Ogundipe
authors.forename: R H
authors.initials: RH
authors.lastname: Allen
authors.forename: S P
authors.initials: SP
authors.lastname: Stabler
authors.forename: J
authors.initials: J
authors.lastname: Lindenbaum
mesh_terms: D000328:Adult; D000368:Aged; D000428:Alcohol Drinking / Q000009:adverse effects; D000748:Anemia, Macrocytic / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis* / Q000209:etiology*; D000749:Anemia, Megaloblastic / Q000097:blood / Q000150:complications / Q000175:diagnosis; D001855:Bone Marrow Diseases / Q000150:complications / Q000175:diagnosis; D003937:Diagnosis, Differential; D064420:Drug-Related Side Effects and Adverse Reactions; D005260:Female; D005492:Folic Acid / Q000097:blood; D005494:Folic Acid Deficiency / Q000097:blood / Q000150:complications / Q000175:diagnosis; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D007958:Leukocyte Count; D008107:Liver Diseases / Q000097:blood / Q000150:complications / Q000175:diagnosis; D008108:Liver Diseases, Alcoholic / Q000150:complications / Q000175:diagnosis; D008297:Male; D008764:Methylmalonic Acid / Q000097:blood; D008875:Middle Aged; D010976:Platelet Count; D011237:Predictive Value of Tests; D011446:Prospective Studies; D017701:Reticulocyte Count; D012680:Sensitivity and Specificity; D014805:Vitamin B 12 / Q000097:blood; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000150:complications / Q000175:diagnosis
chemical_list: D006710:Homocysteine; D008764:Methylmalonic Acid; D005492:Folic Acid; D007770:L-Lactate Dehydrogenase; D014805:Vitamin B 12