Megaloblastic hemopoiesis

R.J. Hayman and M.B. Van Der Weyden. Phytohemagglutinin stimulated normal human peripheral blood lymphocytes in folate depleted medium an in vitro model for megaloblastic hemopoiesis. Blood 55 803, 1980. 

Examination of the bone marrow, although important, will only confirm that the hemopoiesis is megaloblastic. A deficiency of folic acid will also cause a megaloblastic anemia and it is not possible to identify the cause on the basis of morphology. A serum assay of both vitamins will usually indicate which is responsible. If the patient is vitamin B12 deficient, the next step is to carry out a vitamin B12 absorption test to confirm that the deficiency is due to a lack of intrinsic factor. Preferably this should not be done until the patient s vitamin B12 and hemoglobin levels have returned to normal, since the gastric and intestinal cells are also affected by a lack of vitamin B12 aborption may be less than optimal if it is attempted too early. Patients with pernicious anemia also have a histamine-fast achlorhydria and gastric atrophy. The disease appears to have an autoimmune basis and antibodies to intrinsic factor can be demonstrated in the serum of more than half of affected patients. 

There have been other single reports of megaloblastic anemia associated with an apparent abnormality of folate metabolism. One child had a normal serum folate of 6 p,g/liter, an erythrocyte folate of 1480 p.g/liter, and a megaloblastic anemia which responded to treatment with folic acid (VI). Lampkin (Lll) described two sisters with a severe megaloblastic anemia and normal vitamin 6 2 folate levels. Absorption of vitamin 6, 2 normal and both patients excreted an increased amount of formiminoglutamic acid. It was thought that they required both vitamin B 2 and folate to restore normoblastic hemopoiesis. 

In Cuba and the southern United States, nutritional megaloblastic anemias, with or without sprue, seem usually to respond to vitamin B12, according to Suarez et al. (1949) and Spies et al. (1949). Orally administered vitamin B12 was not usually effective. On the other hand. Goldsmith (1951), also working in the southern United States, remarked that daily oral doses of only 5 /ig. of B12 frequently induced satisfactory hemopoiesis in sprue and in nutritional macrocytic anemia. 

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