Macrocytosis is the enlargement of red blood cells with near-constant haemoglobin concentration, and is defined by a mean corpuscular volume (MCV) of greater than 100 femtolitres (the precise criterion varies between laboratories).

Causes

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Most commonly this aetiology is bone marrow dysplasia secondary to alcohol abuse. Other causes may include:

• Vitamin B12 or folate deficiency
• hypothyroidism
• reticulocytosis
• liver disease
• myeloproliferative disease

Complications

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No complications arise from macrocytosis itself and a prognosis will be determined from its aetiology.

Symptoms