In humans, most commonly (especially when the increase in size is mild, and just above normal range) the cause is bone marrow dysplasia secondary to alcohol use disorder. Poor absorption of vitamin B12 in the digestive tract can also cause<unk> . Gastrointestinal diseases that may cause<unk>  include celiac disease (severe sensitivity to gluten from wheat and other grains that causes intestinal damage) and Crohn's disease (inflammatory bowel disease that can affect any part of the gastrointestinal tract). Other causes may include: * megaloblastosis (vitamin B12 or folate deficiency) * hypothyroidism * chronic obstructive pulmonary disease (COPD) * aplastic anemia * reticulocytosis (commonly from hemolysis or a recent history of blood loss). * liver disease * myeloproliferative disease * myelodysplastic syndrome which most commonly presents with macrocytic anemia * chronic exposure to benzene * pregnancy (most common, and requires no treatment as the person affected will return to normal post-partum) * Certain anti-inflammatory drugs, e.g. salazopyrin, azathioprine.
Macrocytosis
Monocytosis
Spherocytosis
Poikilocytosis
Plasmacytosis
Neuroacanthocytosis
Anisocytosis
Mastocytosis