What Is a Megaloblast?

A megaloblast is an abnormally large precursor to red blood cells that will develop into an enlarged red blood cell when it fully matures. The presence of enlarged red blood cells and precursors is a sign of disease. They can appear in patients with a folic acid deficiency, and they also develop in a form of pernicious anemia known as megaloblastic anemia. Blood testing can identify the presence of megaloblasts and may provide more information about why they are developing to allow a doctor to come up with an appropriate recommendation for treatment.

The development of red blood cells requires several stages, all of which a megaloblast will move through as it matures. The enlarged cell has a nucleus and structurally resembles other immature red blood cells, except for the increased size. People with enlarged red blood cells are said to have macrocytosis. This condition usually does not cause any direct symptoms or medical problems, but is a sign of an underlying medical problem that will require treatment.

Treatments can include nutritional supplements, blood transfusions, or the treatment of cancers that lead to the formation of megaloblast cells. A doctor can use blood testing to monitor progress in treatment and determine if the patient needs additional interventions. Once the condition is under control, the doctor may recommend periodic testing for signs of recurrence, to be absolutely sure that the patient is in good health. Patients should also be attentive to symptoms like fatigue or weakness that can indicate anemia and poor circulation.

Often, the presence of megaloblast cells in the blood causes no direct symptoms. Patients may not realize they have a problem until the underlying disease causing the red blood cell enlargement becomes more apparent. This is one of the reasons doctors may recommend periodic blood testing and patient screening even in people who appear to be healthy. A routine test during an annual exam can reveal telltale signs of disease before it manifests, and may allow a doctor to intervene at an early stage in the patient's disease process.

Blood testing of this type typically has a very quick turnaround time. It may be possible for a hospital or clinic to check for megaloblast cells in the blood immediately, as a quick view under the microscope can reveal the abnormal cells. Rapid testing of this nature can eliminate the need for a repeat visit to go over the results and discuss the treatment plan, as the doctor can immediately determine if the patient needs additional testing or treatment.