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July 22, 1983


Author Affiliations

Veterans Administration Medical Center Jackson, Miss

JAMA. 1983;250(4):486. doi:10.1001/jama.1983.03340040030021

In Reply.—  Our article on microcytosis in The Journal was intended not to be encyclopedic but to make physicians aware of those diseases most likely to produce this morphological abnormality. Coexistence of nutritional deficiencies that result in hematologic abnormalities has been recently emphasized by both Spivak1 and Green et al.2 Instead of measuring serum levels of vitamin B12 and folate levels in all seriously anemic patients, a more cost-effective approach would be to scan the stained blood film for evidence of hypersegmentation; if none is seen, determinations of vitamin B12 and folate levels are unnecessary. In fact, a look at the blood smear often provides a clue to the more usual causes of microcytosis, eg, target cells in thalassemia, dimorphism in sideroblastic anemia, and anisochromia in iron deficiency. The uncommon occurrence of severe RBC fragmentation and microcytosis3 would likewise be suggested by this simple yet