Megaloblastic anemia: what it is, symptoms, causes, and treatment

 Megaloblastic anemia: what it is, symptoms, causes, and treatment

Lena Fisher

Megaloblastic anemia has a remarkable characteristic: nucleus-cytoplasm dissociation. Therefore, its main cause is vitamin B12 deficiency. Celso Arrais, onco-hematologist at Hospital Nove de Julho explains what the symptoms of the condition are, and the forms of treatment.

What is megaloblastic anemia?

According to the specialist, megaloblastic anemia is a type of anemia that occurs because of a decrease in vitamin B12 This causes a decrease in the number of red blood cells and, consequently, an increase in the number of red blood cells, as well as a decrease in the size of platelets and white blood cells," he adds.

Thus, it is very important that this type of anemia is identified and treated according to the medical advice of a general practitioner or hematologist.


The doctor explains that there are two ways in which this anemia can present itself:

  • By food deficiency : linked to low intake of the component;
  • By pernicious anemia : when even with an adequate and rich diet of vitamin B12, there is a lack of a protein in the body that synthesizes and absorbs it.

In some cases, there is also the use of medications, such as some anticonvulsants, that block DNA synthesis or that interfere with folic acid metabolism.

What are the symptoms of megaloblastic anemia?

There are fewer RBCs being produced as a result of the decrease in vitamin B12; thus, the hemoglobin in the blood is reduced, making it harder to transport oxygen to the cells and causing symptoms to appear.

According to the professional, the main symptoms are:

  • Loss of appetite;
  • Fatigue ;
  • Pallor;
  • The appearance of spots on the body;
  • Weakening of the nails;
  • Hair loss;
  • Difficulty in concentrating.

In addition, it is also possible to present a clinical picture with weakness, muscle pain, weight loss (as a consequence of loss of appetite), intestinal transit alterations (with diarrhea or constipation), abdominal pain, nausea, or tingling in the hands and feet.


The diagnosis of megaloblastic anemia is made through a complete blood count (CBC) and by determining the amount of vitamin B12 in the blood system. There are also other types of diagnoses that can be made in laboratory tests, for example:

  • CBC analysis to find an increased MCV, characteristic of megaloblastosis;
  • Peripheral blood smear : to find the hypersegmentation of the neutrophil nuclei;
  • Performing the myelogram: may indicate hypercellular bone marrow and nuclear morphological changes, such as large erythroblasts with immature nuclei;
  • Serum cobalamin dosage : when greatly reduced, it strongly suggests the diagnosis of megaloblastic anemia;
  • Serum folate dosage: such as B12 deficiency can lead to an accumulation of serum folate, so erythrocyte folate can be measured;
  • Dosage of methylmalonic acid: to show if the levels are high and if there is a cobalamin deficiency;
  • Dosage of homocysteine indicates both a lack of B12 and folic acid.

Read also: Hemolytic anemia: what is it, main symptoms and treatment

Treatments for megaloblastic anemia

For the hematologist, the treatment of megaloblastic anemia should be prescribed according to the cause of the anemia Vitamin B12 supplementation may be recommended, either orally or even injections with a higher load of VB12, and also an adjustment in the patient's diet with a focus on strategic foods," he adds.

If the treatment is aimed at correcting the diet, then it will be necessary to increase the consumption of vegetables In addition, it may be necessary to supplement with oral folic acid at a dose of 5 mg/day until the cause of the deficiency has been removed.

What are the mild and severe harms of megaloblastic anemia?

The most serious damage from megaloblastic anemia is related to the patient's quality of life: "The patient with this type of anemia is more stunned, more tired in their day-to-day tasks, and may have difficulties in concentration in work, study, and other simple activities of life," he recalls.

It is important to know that some clinical manifestations of vitamin B12 deficiency can range from mild to severe conditions associated with the onset of neurological symptoms.

Is it true that anemia turns into leukemia?

Unfortunately, many people believe that anemia can become leukemia but the specialist informs that this thought is a myth.

"It is important to make it clear that no type of anemia leads to leukemia; it is possible for a leukemia patient to have some anemia, due to the condition of his or her body, but not the other way around; anemia does not evolve into leukemia," he says.

Which antibiotic causes megaloblastic anemia?

Some people also believe that the use of some antibiotics can cause megaloblastic anemia, but the hematologist says this is not common.

"It is rare, but it can happen with the use of some drugs that interfere with DNA replication, such as some antibiotics used in chemotherapy," he comments.


Finally, Celso highlights some habits that can help prevent megaloblastic anemia: "Maintain a balanced diet rich in Vitamin B12 components, with eggs, fish, seafood, and red meat, for example," he says.

Therefore, to prevent this type of anemia, the ideal is to keep the body nourished with vitamin B12 and folic acid, nutrients present in various foods. In addition, for those who are vegetarian However, the ideal is to seek medical advice to verify the best way to supplement.

Source: Celso Arrais, onco-hematologist at Nove de Julho hospital.

Lena Fisher

Lena Fisher is a wellness enthusiast, certified nutritionist, and author of the popular health and well-being blog. With over a decade of experience in the field of nutrition and health coaching, Lena has dedicated her career to helping people achieve their optimal health and live their best life possible. Her passion for wellness has led her to explore various approaches to achieving overall health, including diet, exercise, and mindfulness practices. Lena's blog is a culmination of her years of research, experience, and personal journey towards finding balance and well-being. Her mission is to inspire and empower others to make positive changes in their lives and embrace a healthy lifestyle. When she's not writing or coaching clients, you can find Lena practicing yoga, hiking the trails, or experimenting with new healthy recipes in the kitchen.