Megaloblastic Anemia
The cells require oxygen to function properly. Those responsible for carrying oxygen to the tissues are red cells, also called erythrocytes or RBCs. In the formation of DNA synthesis of the precursor cells of erythrocytes involving both vitamin B12 (cobalmina) and folic acid. If any of these items are missing is a decline in the rate of synthesis of cell DNA, a fact which implies that the red cell precursors increase in size. Furthermore, this alteration in cell maturation can occur makes their destruction, which contributes to anemia.
Thus, erythrocytes come in smaller numbers to the blood and changed in size because of this lack of vitamin B12 or folic acid, resulting in what is known as megaloblastic anemia.
How to produce
Lack of folic acid is the most common cause of megaloblastic anemia. Folic acid is obtained from the diet, from foods like meat, legumes, nuts or vegetables, and is absorbed in the jejunum. It is transported to the bone marrow to intervene in DNA synthesis of red blood cells and collects in deposits in the liver.
The main cause of lack of folic acid is its deficit in the diet, mainly from malnutrition and alcoholism, but may also be due to alterations in the uptake and storage caused by various intestinal and liver diseases, situations that increase their consumption as pregnancy or certain tumors, or certain drugs such as methotrexate, trimethoprim or triamterene.
Vitamin B12 is absorbed in the small intestine after joining in the stomach to a protein called intrinsic factor. Into the blood and transported together with another protein called transcobalamin that leads to bone marrow to intervene in the formation of red blood cells. The portion that is not used is stored in the liver.
Lack of vitamin B12 may be due to a shortage of it in the diet, poor intake of animal products, or a defect in intestinal absorption due to lack of intrinsic factor, alterations in their receptors, alterations of the mucosa intestinal, pancreatic disease or intestinal infections. It can also be caused by misuse of vitamin B12 or by an increased requirement of the same, as in pregnancy, tumors, hyperthyroidism or certain drugs.
Anyway, the most common cause of vitamin B12 deficiency is chronic atrophic gastritis, ie longstanding atrophy of the stomach lining that prevents the vitamin. The atrophy may be due to an autoimmune disease called pernicious anemia, in which the body makes antibodies against the mucosal cells, which prevents the formation of intrinsic factor and thus the absorption of vitamin B12. Furthermore, by a mucosal atrophy, fewer gastric juices, which also hampers the absorption of iron, a fact which can aggravate anemia.
Symptoms
The symptoms of megaloblastic anemia are the classics of anemia, namely, pale skin and mucous membranes, fatigue, dyspnea, palpitations, headache, poor concentration, irritability, insomnia, decreased libido, effects of poor oxygenation tissues. In general, gradually introducing megaloblastic anemia, which these symptoms are generally well tolerated.
When megaloblastic anemia is caused by a vitamin B12 deficiency, other symptoms related to the participation of this substance in the formation of myelin that covers nerves. This implies that demyelinating polyneuropathy may occur as well as involvement at the level of the spinal cord, which results in impairment of vibratory sensation and proprioception (the position to recognize the different parts of the body), which is known as combined degeneration subacute spinal cord. Eventually you can reach a state of dementia. The degree of neurological involvement does not depend on the severity of anemia.
Other alterations that can accompany megaloblastic anemia due to vitamin B12 deficiency are atrophy of the tongue, intestinal malabsorption, blue sclera or vitiligo.
Diagnosis
Diagnosis is based on the interrogation of the patient and analytical data. It should detect symptoms of fatigue, pallor, dyspnea, headache or other neurological disorders, especially in case of suspicion of a vitamin B12 deficiency. Also be used to evaluate the diet that bears the patient and his bowel movements.
Suspecting anemia perform a complete blood test, which should include blood count and basic biochemistry, as well as vitamin B12 and folic acid.
In the analytical appreciate Megaloblastic anemia is a decrease of normal hemoglobin levels. Typically the red cells of megaloblastic anemia are larger and contain more hemoglobin, and this is titrated with specific parameters, which are the mean corpuscular volume (MCV), which assesses the average size of erythrocytes and mean corpuscular hemoglobin (HCM), which measures the average amount of hemoglobin per erythrocyte. Since there is an increase in both the MCV and the MCH, megaloblastic anemia is classified as a macrocytic anemia (larger cells) and hyperchromatic (greater amount of hemoglobin).
Also assessed in blood reticulocytes, ie, young forms of erythrocytes present in blood, which in this case will be elevated. Another characteristic finding a kind of neutrophils and an increase of an enzyme called lactate dehydrogenase (LDH) due to the destruction of erythrocytes occurs.
Levels of vitamin B12 or folic acid can be determined in plasma and they will be reduced if the cause of megaloblastic anemia.
In cases of suspected pernicious anemia blood sought in intrinsic factor antibodies, which are positive in 2 of 3 patients with pernicious anemia, and if there is doubt perform a test called the Schilling test, which allows management by radiolabelled vitamin B12 and intrinsic factor in assessing whether the cause is really a pernicious anemia.
The confirmation test would give megaloblastic anemia bone marrow biopsy but this test is not performed rarely because laboratory findings can accurately diagnose this type of anemia.
Treatment
The treatment will consist of two approaches: first remedy the lack of vitamin B12 or folic acid in the patient and the other address, if possible, cause it originates.
In case of megaloblastic anemia due to lack of vitamin B12 intake should reinforce the patient’s diet to make them have an adequate intake of this vitamin and supplement if necessary with vitamin B12 orally. In more serious cases will be administered intramuscularly. If the cause of megaloblastic anemia is pernicious anemia, should be administered for life. The treatment is accompanied by the administration of folic acid. In the case of pernicious anemia is digestive track patient because of chronic gastritis may eventually develop into a carcinoma of the stomach.
In case you megaloblastic anemia caused by a deficiency of folic acid administered it orally for four months.
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