What is Megaloblastic Anemia?

J.M. Willhite

A blood deficiency involving the production of large erythroblasts within the blood stream is known as megaloblastic anemia. Originating from an underlying deficiency, megaloblastic anemia, also referred to as folate-deficiency anemia or pernicious anemia depending on the cause of the deficiency, can induce a variety of symptoms and increase an individual’s risk for developing serious complications. Treatment for megaloblastic anemia usually involves determining the source of the deficiency and the administration of supplements to compensate for the existing deficit.

Headaches are a symptom.
Headaches are a symptom.

Erythroblasts play a key role in red blood cell formation and are utilized in the process of synthesizing hemoglobin. When a deficiency occurs, it adversely affects red blood cell formation, leading to the development of oversized, abnormally shaped erythroblasts known as megaloblasts. As a result of their slowed development, megaloblasts do not multiply rapidly enough to compensate for their decreased numbers. A megaloblast’s fragile structure makes it susceptible to rupture, ultimately leaving an individual with insufficient red blood cells.

A complete blood count, which involves the counting and examination of red blood cells, is used to test for anemia.
A complete blood count, which involves the counting and examination of red blood cells, is used to test for anemia.

Individuals with megaloblastic anemia generally suffer from a vitamin B12 or folic acid deficiency. With pernicious anemia, there is an insufficient production of a protein known as intrinsic factor within the stomach. The lack of intrinsic factor inhibits the stomach's ability to absorb vitamin B12, which impairs red blood cell production. As an additional consequence of this deficiency, the production of megaloblasts increases, leading to the development of pernicious anemia. Research has found that a folic acid, or folate, deficiency also contributes to megaloblast development since its presence is necessary to promote proper red blood cell formation and maturation.

Secondary, or underlying, conditions and environmental factors have also been known to contribute to the development of folate-deficiency anemia. Individuals with leukemia or bone disorders, such as myelofibrosis, may develop megaloblastic anemia. Regular use of certain medications, such as barbiturates, phenytoin, and alcohol, may also contribute to the development of this form of anemia. Individuals who consume a diet lacking in essential vitamins, nutrients, and minerals or those who have had portions of their small intestine or stomach removed may also develop this type of anemia. Digestive difficulties resulting from disorders such as celiac or Crohn’s diseases or recent infection may promote megaloblastic anemia onset.

Individuals with this form of anemia may experience a variety of symptoms that may include persistent fatigue, pale or yellowish skin, and frequent headaches. Those with pernicious anemia may experience a deficiency of hydrochloric acid within their gastrointestinal tract which may lead to diarrhea, nausea, and a loss of appetite. Additional signs that may develop include physical weakness with minimal exertion, an enlargement of the liver, shortness of breath, and the expulsion of bile through urine and fecal matter.

Tests utilized to confirm a diagnosis of pernicious anemia may include a complete blood count and, in some cases, a bone marrow examination. Also known as a sternal tap, a bone marrow examination involves the collection of bone marrow fluid obtained with a hollowed needle inserted into either the breast or pelvic bone. A Schilling test may also be administered in phases to evaluate the body's ability to absorb vitamin B12 and to check B12 levels.

Once the cause of the anemia is determined and the extent of the deficiency identified, treatment usually involves the use of supplements to compensate for the deficiency. If the anemia is due to a vitamin B12 deficiency, monthly B12 injections may be administered and dietary changes are recommended to restore proper levels. The B12 supplement may also be inhaled or administered orally.

Individuals whose anemia is due to a folate deficiency may undergo short-term injections of folic acid supplements until the condition is corrected. The supplement may also be administered orally over the short term. For individuals whose folate deficiency is caused by the improper absorption of folic acid by the intestine, lifelong supplement use may be necessary.

Complications associated with megaloblastic anemia may include the development of gallbladder disease, gastric polyps, and stomach cancer. Individuals with megaloblastic anemia are at an increased risk for developing neurological problems if the deficiency is left untreated. Additional complications may include infertility, congestive heart failure, and permanent skin discoloration.

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