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Megaloblastic Anemia

What is Megaloblastic Anemia?

Megaloblastic anemia is a medical disorder of the blood, in which the DNA synthesis is inhibited during the red cell production phase. What happens is that the red blood cells continue to grow without actually going into the secondary division phase. This process is known as mastocytosis and it leads to the appearance of red blood cells that are large and immature. These red blood cells are known as megaloblasts, hence the name of the condition. These cells are dysfunctional and they cause the symptoms of anemia, along with the presence of hypersegmented neutrophils in the peripheral blood.


These are the most common symptoms of megaloblastic anemia:

  • Appetite loss (which ultimately leads to weight loss)
  • Weakness at the level of the muscles
  • State of general fatigue
  • Accelerated intestinal transit (diarrhea)
  • Nausea and vomiting
  • Changes in the heart rhythm (tachycardia – increased heart rate)
  • The tongue has a smooth surface and it is tender (condition known as glossitis, being caused by the loss of papillae)
  • Tingling experienced at the level of the extremities (hands and feet)
  • Numbness can also be present at the level of the extremities
  • In severe cases, apart from the tachycardia, the patient also presents difficulties breathing (dyspnea) and cardiopulmonary distress
  • If the bilirubin level is also increased, the patient’s skin and eye sclera can turn yellow (jaundice)
  • In some patients, due to the increased synthesis of melatonin, the skin can become excessively pigmented (the hair color will become darker as well)
  • Mental changes can occur as well, causing the patient to become irritable and even enter into a state of psychosis
  • Other symptoms that can be present include:
    • Abnormal gait
    • Loss of balance
    • Impairment of the speech
    • The proprioceptive and sensory systems are affected as well
    • Malabsorption, with the following sub-symptoms – distension of the abdomen and steatorrhea.


Unlike other types of anemia, this condition has a gradual onset, as the defect in the DNA synthesis is often caused by a vitamin deficiency. Most often, the patient presents a deficiency of B12 vitamin or folic acid. Megaloblastic anemia might also be caused by copper deficiency or by the administration of certain medication (chemotherapy treatments, anti-microbial agents for different types of infection). Another cause of this medical problem is myelodysplasia, a type of bone marrow cancer that affects the regular production of red blood cells.

Diagnosis of Megaloblastic Anemia

Megaloblastic anemia can be identified or diagnosed through the following methods:

  • Blood testing
    • Complete blood count
    • Red blood cell folate level
    • Schilling diagnostic test – evaluates the absorption of vitamin B12
    • Other initial workup includes:
      • Peripheral smear
      • Reticulocyte count – low in individuals who suffer from this type of anemia
      • Lactate dehydrogenase – severely increased in megaloblastic anemia
      • Indirect bilirubin
      • Iron and ferritin levels
  • Medical history of the patient
  • Examination of the patient – clinical signs
  • Bone marrow aspiration
    • Confirmation of vitamin B12 deficiency diagnosis
    • Useful for ruling out other medical conditions, such as myelodysplasia
    • Can also be used to check out the levels of iron.

The differential diagnosis of megaloblastic anemia can be made with the following medical problems:

  • Neoplasm
  • Acute leukemia
  • Liver disease
  • Dysfunctions of the thyroid gland (hypothyroidism)
  • Hemolytic anemia


If the megaloblastic anemia is not caused by different medication or is not a direct result of the bone marrow cancer, then the megaloblastic anemia treatment is pretty standard. It will attempt to reduce the vitamin deficiency the patient experiences and it will consist of vitamin B12 and/or folic acid supplements. This is a chronic condition and the development is slow, so the blood transfusions are not considered as suitable megaloblastic anemia treatment (in the majority of the cases). This is because the patient has already adapted to the reduced levels of hemoglobin and the blood transfusion will not bring any positive changes.

When is the blood transfusion recommended as megaloblastic anemia treatment? The doctor might decide to use the blood transfusion as a course of treatment in patients who exhibit severe anemia symptoms, symptoms that are actually life-threatening.

Synthetic B12 vitamin is administered as megaloblastic anemia treatment in the form of intramuscular injections. The dose will be higher until the hemoglobin levels improve and then the dose will be readjusted. As this is a chronic condition, the megaloblastic anemia treatment is administered for life. If the patient suffers from hemophilia and presents an increased risk for hemorrhage, then the synthetic B12 vitamin will be administered orally. Some doctors recommended that the treatment is started with the injections and the continued with the oral administration, one the symptoms start to improve.

Folic acid can be administered orally as megaloblastic anemia treatment. Also, the patient might benefit from a diet that is rich in folic acid (green leafy vegetables). Before administering folic acid, investigations should be made to determine whether the patient suffers from vitamin B12 hypovitaminosis or not. While the folic acid will improve the symptoms of the anemia, it will not have an effect on the neurological symptoms that the B12 deficiency causes. This is why it is recommended for these two (B12 and folic acid) to be administered at the same time.
In conclusion, megaloblastic anemia is a serious condition and it should be treated as such. It is important that the symptoms of this medical problem are correctly identified, so as the adequate treatment can be recommended. As you have had the opportunity to read, the diet is also of major importance when it comes to improving the symptoms of the megaloblastic anemia. Patients are advised to make the necessary changes in their diet, including leafy greens and other healthy vegetables or fruits. Regular check-ups and blood testing is required, so as to guarantee a constant monitoring of the patient diagnosed with anemia. Based on the results of these regular check-ups, the doctor can change the treatment or stop the treatment altogether. You should not hesitate, however, to maintain the same healthy diet, even after you have finished the anemia treatment.

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