Megaloblastic anemia

Description, Causes and Risk Factors: Megaloblastic anemias are a heterogeneous group of disorders that have common blood abnormalities and symptoms. The characteristic blood picture consists of large oval erythrocytes, hypersegmented neutrophils and large abnormal platelets. Megaloblastic anaemia results from abnormal maturation of haematopoietic cells due to faulty DNA synthesis. Two vitamins, cobalamin (vitamin B12) and folic acid are essential for DNA biosynthesis. Deficiency of either vitamin results in asynchrony in the maturation of the nucleus and cytoplasm of rapidly regenerating cells. In the haematopoietic system this asynchrony results in abnormal nuclear maturation with normal cytoplasmic maturation, apoptosis, ineffective erythropoiesis, intramedullary haemolysis, pancytopenia and typical morphological abnormalities in the blood and marrow cells. Causes and Risks Factors:
  • This disease is also caused by inadequate secretion of IF (intrinsic factor) by the parietal cells in the stomach — due to atrophy of the gastric mucosa or autoimmune destruction of the parietal cells. It is found most often in older individuals, particularly in those of northern European descent or in African Americans. It is less common in southern Europeans and Asians.
  • Imurslund-Grasbeck syndrome is another documented cause for megaloblastic anemia. It is an autosomal recessive disorder characterized by intestinal vitamin B12 malabsorption and proteinuria.
  • Poverty and malnutrition continues to cause cobalamin deficiency and leads to megaloblastic anemia.
Symptoms: Symptoms may include the following:
  • Weakness, especially in the arms and legs.
  • Sore tongue.
  • Nausea, appetite loss, and weight loss.
  • Numbness or tingling in the hands and feet.
  • Difficulty maintaining proper balance.
  • Pale lips, tongue, and gums.
  • Yellow eyes and skin.
  • Bleeding gums.
  • Shortness of breath.
  • Depression, confusion, poor memory, and dementia.
  • Headache.
  • Ringing in the ears (tinnitus).
Diagnosis: Differential diagnosis may include:
  • Alcoholism.
  • Medication-induced macrocytosis.
  • Liver disease-associated macrocytosis.
  • Hypothyroidism.
  • Infiltrative disorders of the bone marrow.
  • Nitrous oxide abuse.
  • Splenectomy-induced macrocytosis.
A complete blood picture including red blood cells, white blood cells, and platelet morphology and count and a careful examination of bone marrow smears is usually sufficient to diagnosis megaloblastic anemia. Other tests may include:
  • Test for methylmalonic acid in the serum as an indicator of vitamin B12 deficiency.
  • Test for homocysteine to check folate levels.
Cytopenia are important feature of megaloblastic anemia. Every case of cytopenia should undergo bone marrow aspiration for confirmation of its diagnosis. A Schilling test will confirm that the vitamin B12 deficiency is the result of intestinal malabsorption due to intrinsic-factor deficiency. In patients with pernicious anemia, urinary excretion of orally administered vitamin B12 is low, and it increases if vitamin B12 is administered with intrinsic factor. A simpler test is measurement of serum holotranscobalamin II, the circulating protein that delivers vitamin B12 to cells. In patients with vitamin B12 deficiency, serum concentrations of holotranscobalamin II fall before those of vitamin B12. Treatment: Specific treatment for megaloblastic anemia will be determined by your physician based on your age, overall health, and medical history, extent of the disease, your tolerance for specific medications, procedures, or therapies, expectations for the course of the disease, your opinion or preference. Treatment usually involves treating the underlying cause for the anemia which may include your child taking an oral dietary folic acid supplement for at least two to three months. If the disorder is caused by an absorption problem in the digestive tract, this may need to be treated first. Shotgun therapy may be used where the causative agent is unclear. Folate, then vitamin B12 attempts to make the patient well. Intramuscular hydroxocobalamin daily for a week (regime will depend on the cause of the anaemia). Monitor the reticulocyte count (should return to normal in 2-3 weeks) and the hemoglobin concentration (20-30g/L rise every week until normal) Some doctors recommend that elderly patients with gastric atrophy take vitamin B12 supplements by mouth in addition to monthly injections. There is also a preparation of vitamin B12 that may be given through the nose. For some people, taking vitamin B12 by mouth in a very high dose can also be an effective treatment. A well-balanced diet is essential to provide other elements for healthy blood cell development, such as folic acid, iron, and vitamin C. To prevent loss of folate, foods should not be cooked excessively, especially in large amounts of water. To prevent cobalamin deficiency, patients who prefer vegetarian diets should include dairy products and eggs in their meals NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.  


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