Megaloblastic anemia is a hematological disorder that characterized by abnormally large cells that have arrested in nuclear maturation. Megaloblastic anemia can present with a variety of symptoms and is chiefly caused by deficiencies in folate and vitamin B12 (cobalamin).
Not all patients with megaloblastic anemia are symptomatic . Patients with megaloblastosis may present with a history of the following features:
Patients with suspected megaloblastic anemia usually require a comprehensive workup that includes the following :
The treatment of megaloblastic anemia depends on the cause .
Today many foods including cereals are fortified with folic acid supplements to reduce risk of malignancies (eg. colon, pancreas). However, it is important to note that fortifying foods with folate can lead to cobalamin-induced neuropsychiatric disorders. It is vital that no patient be started on only folate therapy in a patient with megaloblastic anemia until cobalamin deficiency has been ruled out. Giving only folate to improve the anemia will not correct the neuropsychiatric symptoms of cobalamin deficiency and can in fact worsen them. If not sure, both folate and cobalamin should be administered if cobalamin deficiency cannot be ruled out.
Once treatment has started, all patients need follow up and monitoring to determine if improvements occurring in the blood tests and clinical exam.
In individuals in whom the cause of megaloblastic anemia is temporary and is known, the prognosis is good. Patients with unknown diagnosis are at risk for developing anemia related complications and hypokalemia during treatment. If the cobalamin deficiency is missed or not appropriately treated, patients can develop permanent neuropsychiatric manifestations including subacute combined degeneration of the spinal cord. Pregnant women who do not take folate supplements are at risk for giving birth the infants with neural tube defects.
The most common causes of megaloblastic anemia open link are deficiencies of vitamin B12 and/or folic acid. Cobalamin deficiency may be caused by:
Stores of folate are limited and deficiency can develop in a matter of weeks if there is complete cessation of folate intake. Folate deficiency causes include:
Globally the most common cause of megaloblastic anemia is ill preparation of foods containing folate. The incidence of megaloblastic anemia is most common in countries where there is malnutrition and in countries where routine administering of folate to pregnant women and elderly individuals is not common.
Vitamin B12 is chiefly obtained from sea foods, meat and dairy products. Fruits and vegetables do not contain significant amounts of this vitamin. Vitamin B12 plays a vital role in numerous biochemical reactions in the body. It is critical for the process of myelination. Cobalamin deficiency can lead to abnormal myelination which can affect the spinal cord.
Unlike vitamin B12, folate is found in large amounts in fruits, vegetables and animal protein. Because most available dietary folate is in a conjugated form, it needs to be converted to dihydrofolic acid so that it can be absorbed; folate is readily absorbed from the small intestine and does not require the presence of intrinsic factor.
In megaloblastic anemia, there is decreased deoxythymidine triphosphate (dTTP) synthesis resulting in impairment in the synthesis of DNA, RNA and protein. The red blood cells (RBCs) that are produced show slowed nuclear maturation whereas cytoplasmic maturation is relatively unaffected. There is also rapid destruction of defective RBCs in the bone marrow. The impaired production and increased destruction of RBCs in the bone marrow results in anemia. Direct interference of DNA synthesis causing megaloblastic anemia may also occur due to HIV infections and myelodysplastic disorders.
The uptake of cobalamin is from the intestine is a complex process. Ingested cobalamin initially binds in a nonspecific manner the protein molecules in food. In the presence of gastric acidity, the cobalamin is released and then binds to R-proteins that protect it from degradation by the intestinal enzymes and secretions. This cobalamin-R protein complex then reaches the terminal ileum where it requires the presence of intrinsic factor to be absorbed into the systemic circulation. The complex is then absorbed in the terminal ileum and then transported to the bone marrow . Because cobalamin is stored in the body and very little cobalamin is required on a daily basis, deficiency of this vitamin can take several years to develop. On the other hand, folate is not stored and hence deficiency usually occurs in a matter of weeks after dietary intake is discontinued.
There are many causes of megaloblastic anemia and not all can be prevented. However, in patients with a strict vegetarian diet, supplements of folate and cobalamin should be recommended. In addition, these individuals should be educated on eating foods that are fortified with these supplements and also learn how to prepare foods. Examples of foods with high levels of folate include broccoli, asparagus, lettuce, spinach, bananas, liver, melons and mushrooms. To prevent loss of folate from foods, dilution in large amounts of water and excessive heating should be avoided. After discharge all patients must be monitored to ensure that the anemia is resolving. Periodic testing of hemoglobin, LDH, indirect bilirubin levels and blood smear is recommended.
Megaloblastic anemia is a hematological disorder where certain cells of the bone marrow have arrested during the phase of nuclear maturation. These large cells are referred to as megaloblasts and can be easily seen on a blood smear. Megaloblastic anemia can be associated with diverse clinical manifestation ranging from personality changes, neurological deficits, glossitis and pancytopenia. Asides from medications, folic acid deficiency and vitamin B12 deficiency are the most common causes of this anemia. Any process that interferes with absorption of cobalamin or folate from the intestine can potentially cause the disorder.
The condition is seen globally but most common in people with restricted diets and in presence of malnutrition. It is important to note that megaloblastic anemia that occurs with either folate or cobalamin deficiency can present with almost identical signs and symptoms, but the latter is also associated with subacute combined degeneration of the spinal cord. Adults usually require at least 5-7 microgram of cobalamin and about 0.4 mg of folate per day  .
Megaloblastic anemia is a type of blood disorder that results in abnormal cells in the blood circulation and bone marrow. Megaloblastic anemia can occur because of deficiency in folate or vitamin B12. Most people develop this type of anemia either because they have a deficient diet or they are unable to absorb the vitamin from the intestine.
Megaloblastic anemia can present with a variety of symptoms that include a red painful tongue, changes in personality, difficulty with balance and walking, burning or numbness in the legs, pale skin, weight loss and weakness.
The diagnosis of this anemia can be made by looking at a blood smear or performing other blood tests that can look at levels of the vitamins. Once diagnosed, treatment is required. If the treatment with folate and vitamin B12 is done promptly, the symptoms do reverse within a few months. To prevent megaloblastic anemia, people who eat a strict vegetarian diet should take supplements of folate and vitamin B12. Foods high in folate include broccoli, liver, melons and spinach. All women who get pregnant should take folate supplements to avoid developing spinal cord problems in the infant.