Macrocytosis

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
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Macrocytosis
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Often asymptomatic, may include fatigue, pallor, jaundice
Complications	Anemia, neurological symptoms if due to vitamin B12 deficiency
Onset	Varies depending on underlying cause
Duration	Depends on treatment and underlying cause
Types	N/A
Causes	Vitamin B12 deficiency, folate deficiency, liver disease, alcoholism, hypothyroidism, reticulocytosis
Risks	Alcohol use disorder, malnutrition, autoimmune disorders
Diagnosis	Complete blood count showing increased mean corpuscular volume (MCV)
Differential diagnosis	Megaloblastic anemia, non-megaloblastic macrocytic anemia
Prevention	Adequate intake of vitamin B12 and folate, moderation of alcohol consumption
Treatment	Address underlying cause, vitamin B12 or folate supplementation
Medication	N/A
Prognosis	Good with appropriate treatment
Frequency	Common, especially in older adults
Deaths	N/A

Macrocytosis is a condition characterized by the presence of abnormally large red blood cells (RBCs) in the blood. It is often identified through a complete blood count (CBC) test, which reveals an increased mean corpuscular volume (MCV) of the red blood cells.

Causes

Macrocytosis can be caused by a variety of factors, including:

• Vitamin B12 deficiency
• Folate deficiency
• Liver disease
• Alcoholism
• Hypothyroidism
• Certain medications, such as chemotherapy drugs
• Bone marrow disorders

Pathophysiology

Macrocytosis occurs when the red blood cells are larger than normal. This can be due to impaired DNA synthesis, which affects the maturation of the red blood cells. In conditions like vitamin B12 or folate deficiency, the lack of these essential nutrients leads to ineffective erythropoiesis and the production of larger, immature red blood cells.

Diagnosis

The diagnosis of macrocytosis is typically made through a CBC test, which measures the MCV. An MCV greater than 100 femtoliters is indicative of macrocytosis. Further tests may be conducted to determine the underlying cause, such as measuring serum vitamin B12 and folate levels, liver function tests, and thyroid function tests.

Treatment

Treatment of macrocytosis depends on the underlying cause. For example:

• Vitamin B12 deficiency is treated with vitamin B12 supplements.
• Folate deficiency is treated with folic acid supplements.
• Alcohol-related macrocytosis may improve with reduced alcohol consumption.
• Treating underlying liver or thyroid conditions can also resolve macrocytosis.

See Also

• Anemia
• Pernicious anemia
• Megaloblastic anemia
• Red blood cell