Anemia, macrocytic

A type of anemia characterized by larger than normal red blood cells

Macrocytic anemia
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Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Fatigue, weakness, pallor
Complications	Heart failure, neurological symptoms
Onset
Duration
Types	N/A
Causes	Vitamin B12 deficiency, folate deficiency, alcoholism, certain medications
Risks	N/A
Diagnosis	Blood tests, bone marrow biopsy
Differential diagnosis	N/A
Prevention	N/A
Treatment	Vitamin supplementation, dietary changes, treating underlying causes
Medication	N/A
Prognosis	Generally good with treatment
Frequency
Deaths	N/A

Macrocytic anemia is a type of anemia characterized by the presence of abnormally large red blood cells (RBCs) in the blood. The term "macrocytic" refers to the increased size of the RBCs, which is typically measured by the mean corpuscular volume (MCV) in a complete blood count (CBC). An MCV greater than 100 femtoliters is generally considered indicative of macrocytic anemia.

Causes

Macrocytic anemia can be caused by a variety of factors, most commonly due to deficiencies in vitamin B12 or folate. These vitamins are essential for DNA synthesis, and their deficiency leads to impaired cell division, resulting in larger than normal red blood cells.

Vitamin B12 Deficiency

Vitamin B12 deficiency can occur due to inadequate dietary intake, malabsorption syndromes such as pernicious anemia, or gastrointestinal surgeries that affect the absorption of vitamin B12.

Folate Deficiency

Folate deficiency may result from poor dietary intake, increased requirements during pregnancy, or malabsorption conditions such as celiac disease.

Other Causes

Other causes of macrocytic anemia include:

• Alcoholism: Chronic alcohol consumption can interfere with folate metabolism and lead to macrocytosis.
• Certain medications: Drugs such as methotrexate, zidovudine, and hydroxyurea can cause macrocytic anemia.
• Liver disease: Liver dysfunction can alter the lipid composition of the red blood cell membrane, leading to macrocytosis.

Symptoms

The symptoms of macrocytic anemia are similar to those of other types of anemia and may include:

• Fatigue
• Weakness
• Pallor
• Shortness of breath
• Dizziness

In cases of vitamin B12 deficiency, neurological symptoms such as numbness, tingling, and cognitive disturbances may also occur.

Diagnosis

Diagnosis of macrocytic anemia involves:

• Complete blood count (CBC): To measure the MCV and confirm macrocytosis.
• Blood smear: To examine the morphology of red blood cells.
• Serum vitamin B12 and folate levels: To identify deficiencies.
• Bone marrow biopsy: In certain cases, to assess bone marrow function and rule out other hematological disorders.

Treatment

Treatment of macrocytic anemia focuses on addressing the underlying cause:

• Vitamin B12 supplementation: Administered orally or via intramuscular injections.
• Folate supplementation: Oral folic acid is given to correct folate deficiency.
• Dietary changes: Increasing intake of foods rich in vitamin B12 and folate.
• Treating underlying conditions: Such as managing alcoholism or adjusting medications.

Prognosis

With appropriate treatment, the prognosis for macrocytic anemia is generally good. Most patients respond well to vitamin supplementation and dietary modifications.

Also see

• Anemia
• Pernicious anemia
• Vitamin B12 deficiency
• Folate deficiency
• Megaloblastic anemia