Causes, Symptoms, Treatment and Tests For Megaloblastic Anemia

Submitted on March 27, 2012

In megaloblastic anemia, the body is unable to produce sufficient red blood cells that are healthy due to a deficiency of folate or cobalamin (vitamin B12) deficiency. The red blood cells in the megaloblastic anemia patient's blood are larger than normal, and hence the name, megaloblastic anemia. The life span of these dysfunctional red cells is less than 120 days, which is how long normal red blood cells circulate in the body. Folate or folic acid is required for the formation of red blood cells and their growth. Since the body does not store it in large quantities, one needs to eat a diet rich in folate to meet the demand for the production of red blood cells. Without enough healthy red blood cells the body is unable to provide oxygenated blood to all the tissues. With time, symptoms of anemia like fatigue and pale skin begin to manifest slowly. Pernicious anemia, a type of autoimmune condition characterized by malabsorption of vitamin B12 is also a type of megaloblastic anemia. Early detection and treatment can alleviate the symptoms, and cobalamin and folate therapy may be started to arrest the progress of cobalamin-related neurological disorders.

Tests Recommended

A complete blood count and a peripheral smear may be the first tests ordered by the doctor when he/she suspects megaloblastic anemia. The presence of abnormally large cells will be detected in these tests. Medical Tests of vitamin B12 and folate deficiency including serum cobalamin levels and serum folate levels are also done to enable the right choice of therapy.

Megaloblastic anemia tests include serum methylmalonic acid and homocysteine test as high levels in these test results often indicate cobalamin deficiency. Urine assessments and a modified Schilling test may be ordered in some cases to confirm diagnosis. Serum iron and ferritin assays are done both before and during therapy to ensure that patients have enough iron in their body to effectively respond to cobalamin and folate therapies.


A combined deficiency of folate and cobalamin or vitamin B12 may be the reason behind megaloblastic anemia. Physicians order tests to identify the cause of the deficiency to decide on the course of the treatment and the supplements needed. Certain gastrointestinal diseases like celiac disease and alcohol abuse may impede the absorption of nutrients from food. Certain medication and barbiturates are known to interfere with the absorption of folic acid. A vegan who does not eat eggs or dairy products over a long period of time is susceptible to dietary insufficiency of cobalamin. Certain auto immune disorders resulting from thyroid problems or Addison's disease or type I diabetes may be the cause of pernicious anemia. Megaloblastic anemia in childhood may be due to congenital disorders leading to vitamin B12 deficiency. Tapeworm infestation in the intestine can also interfere with the absorption of the vitamin. Even if a person eats food rich in folate, faulty cooking methods like using too much heat or water can destroy folic acid in food. Megaloblastic anemia causes could be as simple as increased folate requirement due to pregnancy and lactation. Skin diseases like psoriasis and exfoliative dermatitis could hike the demand for folic acid because of the rapid shedding of epidermal cells. Tropical sprue can lead to both folate and vitamin B12 deficiency.


Megaloblastic madness refers to the personality changes, dementia, depression, and acute psychosis that are neurological manifestations of vitamin B12 deficiency. A wobbly gait, numbness in hands and legs, memory loss, etc. are some of megaloblastic anemia effects seen in elderly patients, though often they are attributed to age-related disorders. Infertility is also one of the effects of this type of anemia. In severe cases of vitamin B12 deficiency, the spinal cord may begin to degenerate.

Weak muscles in the lower limbs are another long-term effect noticed. Damage to the optic nerve and diminished is relatively rare but are known to be the effect of this vitamin deficiency.


Psychiatric symptoms such as irritability, aggressiveness that reflects a marked personality change, and memory loss are megaloblastic anemia symptoms commonly noticed among the elderly when there is a suspicion of a vitamin b12 deficiency.

Gastrointestinal symptoms in the form of constipation or diarrhea, nausea, and loss of appetite are seen in several patients with megaloblastic anemia. A swollen shiny tongue and ulcers in the mouth indicate the deficiency of vitamin B12 and folic acid. Pins and needles in the hands and feet, uneven gait, headaches and memory loss accompanied by pale skin may be other symptoms noticed by the patients and physicians.


The first line of megaloblastic anemia treatment involves cobalamin and folate therapies, once the cause of the deficiency is established. Treating patients with cobalamin deficiency with just folate is not advisable as it may alleviate the symptoms of anemia, but neuropsychiatric symptoms may persist. Administering folate during pregnancy, particularly in vegetarian mothers is vital to avoid megaloblastic anemia in infants. For those who lack the intrinsic factor necessary for the absorption of vitamin B12, injections of the vitamin bypass the gastrointestinal tract and replenish the body's stores. Oral doses of vitamin B12 and folic acid can be given for those who are on a restricted diet like vegetarians, diabetics, and the elderly. Since iron deficiency can complicate the production of red blood cells, combined treatment for iron deficiency and folic acid deficiency along with vitamin B12 supplements may prove more effective in the treatment of megaloblastic anemia.

In the case of those with a reduced capacity for the absorption of vitamin B12 as with those who have undergone gastrointestinal surgeries and those with congenital autoimmune disorders, cobalamin and folate therapy may be needed all through their lives. The easiest and cheapest treatment for megaloblastic anemia is to make dietary changes to include folate and cobalamin rich foods in the diet. Eating plenty of green leafy vegetables, eggs, seafood, and red meat provides the body with enough folate, cobalamin, and iron for the production of healthy red blood cells. Vegans and vegetarians in particular should take care to include supplements of vitamin B12 in their daily routine as this vitamin is found only in animal products.