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Macrocytosis is a term used to describe red blood cells that are larger than normal. When observed under the microscope on a blood smear, macrocytosis is reported as “slight” to ++++ (“four plus”). This observation helps in diagnosing and distinguishing between different types of anemia, which can be considered microcytic, normocytic or macrocytic, depending on the size of the red blood cells. A high MCH (mean corpuscular volume) can also indicate macrocytosis.

Macrocytosis can be observed in anemias caused by folate or Vitamin B12 deficiency (syndromes of malabsorption, malnutrition or pernicious anemia) or in alcoholism. Thyroid or bone marrow dysfunction or the use of certain immunosuppressive and anti-cancer drugs can also cause macrocytosis.

Term of the Week

Hot zone

A hot zone is a section of a facility (sometimes an entire facility or even a city district) where there is a high risk of contamination by patients with an infectious disease. All individuals entering a hot zone must respect appropriate protective measures. By analogy, “cold zone” and “warm zone” are used to refer to areas where there is no infected individual or only individuals suspected of having an infection.