Macrocytosis--an Australian general practice perspective.

BACKGROUND: Clinicians' approaches to identifying and investigating red blood cell macrocytosis are variable. There is little literature on the Australian primary care approach.

METHODS: Mean corpuscular volume (MCV) in blood counts from an urban Australian general practice were calculated and general practitioners in the surrounding division were surveyed on their experience of and approach to investigating macrocytosis.

RESULTS: Mean corpuscular volume above 100 fL was found in 1.7% of patients, and 7.3% had an MCV above 96 fL. Ninety-four percent of responding GPs replied they would further investigate this clinical finding, particularly at levels above 100 fL. Alcohol excess and vitamin B12 deficiency were the most common single causes of macrocytosis in their experience.

DISCUSSION: Macrocytosis can be a marker for disease and it is important to identify and investigate its presence. Further research is needed to clarify the reference range for healthy adults in general practice and to formulate evidence based clinical guidelines for investigating isolated macrocytosis.