Megaloblastic Anemia

Megaloblastic anemias are a heterogeneous group of disorders that share common morphologic characteristics.

  • Erythrocytes are larger and have higher nuclear-to-cytoplasmic ratios compared to normal cells
  • Neutrophils can be hypersegmented
  • Megakaryocytes are abnormal

On the cellular level in megaloblastic cells, the maturation of nucleus is delayed, while cytoplasmic development is normal and is characterized by very large red blood cells. This malformation causes the bone marrow to produce fewer cells, and sometimes the cells die earlier than the normal 120-day life expectancy. Instead of being round or disc-shaped, the red blood cells can be oval.


The cause of megaloblastic anemias is diverse, but a common basis is impaired DNA synthesis. The most common source in children occurs from a vitamin deficiency of folic acid or vitamin B-12. Other sources of megaloblastic anemia include the following:

  • Digestive diseases: Certain diseases of the lower digestive tract can lead to megaloblastic anemia. These include celiac disease, chronic infectious enteritis and enteroenteric fistulas. Pernicious anemia is a type of megaloblastic anemia caused by an inability to absorb vitamin B-12 due to a lack of an intrinsic factor in gastric (stomach) secretions. This intrinsic factor enables the absorption of vitamin B-12.
  • Malabsorption: Inherited congenital folate malabsorption, a genetic problem in which infants cannot absorb folic acid in their intestines, can lead to megaloblastic anemia. This requires early intensive treatment to prevent long term problems such as mental retardation.
  • Medication-induced folic acid deficiency: Certain medications, specifically ones that prevent seizures, such as phenytoin, primidone and phenobarbital, can impair the absorption of folic acid. The deficiency can usually be treated with a dietary supplement.
  • Folic acid deficiency: Folic acid is a B vitamin required for the production of normal red blood cells. Folic acid is present in foods such as green vegetables, liver and yeast. It is also produced synthetically and added to many food items.


While each child may experience megaloblastic anemia differently, symptoms may include:

  • Gastrointestinal symptoms such as:
    • Loss of appetite
    • Weight loss
    • Nausea
    • Constipation
    • Sore tongue and canker sores
    • Symptoms of anemia
    • Early neurological symptoms, including:
      • Paresthesias in the feet and fingers
      • Poor gait
      • Memory loss
      • Later neurological symtoms, including:
        • Severe disturbances in gait
        • Loss of position sense
        • Blindness due to optic atrophy
        • Psychiatric disturbances

        In some patients, neurological impairment can occur without anemia. Therefore, neurological symptoms may range from mild to severe and cobalamin deficiency should be considered even with minimal neurological symptoms and the absence of anemia.

        Symptoms of megaloblastic anemia may resemble other blood conditions or medical problems. Always consult your child’s physician for a diagnosis.

        Diagnosis and Treatment

        How is Megaloblastic Anemia Diagnosed?
        Megaloblastic anemia may be suspected from general findings from a complete medical history and physical examination of your child. In addition, several blood tests can be performed to confirm the diagnosis.

        If the megaloblastic anemia is thought to be caused from a problem in the digestive tract, a barium study of the digestive system may be performed.

        How is Megaloblastic Anemia Treated?
        Specific treatment for megaloblastic anemia is determined by your child’s physician based on:

        • Your child’s age, overall health and medical history
        • Extent of the anemia
        • Cause of anemia
        • Your child’s tolerance for specific medications, procedures or therapies
        • Expectations for the course of the anemia

        Treatment usually involves treating the underlying cause for the anemia which amy include your child taking an oral dietary folic acid supplement for at least two to three months. If the disorder is caused by an absorption problem in the digestive tract, this may need to be treated first.


        Patients should include rich sources of folate in their diets. Examples include:

        • Asparagus
        • Broccoli
        • Spinach
        • Lettuce
        • Lemons
        • Bananas
        • Melons
        • Liver
        • Mushrooms

        To prevent loss of folate, foods should not be cooked excessively, especially in large amounts of water. To prevent cobalamin deficiency, patients who prefer vegetarian diets should include dairy products and eggs in their meals.