For this patient, the correct answer would be an abnormal GGT, because chronic moderate to heavy alcohol use can raise GGT levels, as well as MCVs.
Dr. David Savage and colleagues evaluated the etiology of macrocytosis in 300 consecutive hospitalized patients with macrocytosis.2 They found that the most common causes were medications, alcohol, liver disease, and reticulocytosis. The study was done in New York and was published in 2000, so zidovudine (AZT) was a common medication cause of the macrocytosis. This medication is much less commonly used today. Zidovudine causes macrocytosis in more than 80% of patients who take it. They also found in the study that very high MCVs (> 120) were most commonly associated with vitamin B12 deficiency.
Dr. Kaija Seppä and colleagues looked at all outpatients who had a blood count done over an 8-month period. A total of 9,527 blood counts were ordered, and 287 (3%) had macrocytosis.1 Further workup was done for 113 of the patients. The most common cause found for macrocytosis was alcohol abuse, in 74 (65%) of the patients (80% of the men and 36% of the women). No cause of the macrocytosis was found in 24 (21%) of the patients.
Dr. A. Wymer and colleagues looked at 2,800 adult outpatients who had complete blood counts. A total of 138 (3.7%) had macrocytosis, with 128 of these patients having charts that could be reviewed.3 A total of 73 patients had a workup for their macrocytosis. Alcohol was the diagnostic cause of the macrocytosis in 47 (64%). Only five of the patients had B12 deficiency (7%).