Features:
(1) anemia with normal MCV and sometimes normal MCH
(2) increased RDW (RBC distribution width)
(3) folate or vitamin B12 deficiency, with (a) hypersegmented neutrophils and (b) giant myelocytes and metamyelocytes
(4) some form of microcytic anemia: iron deficiency, thalasssemia or anemia of chronic disease
Some common situations when to suspect:
(1) after total gastrectomy (combined iron and vitamin B12 deficiencies)
(2) during pregnancy (combined iron and folate deficiencies)
(3) some malabsorption states
(4) alcoholic with gastrointestinal bleeding and malnutrition
If a combined deficiency of iron and folate or vitamin B12 is identified, replacement of all the deficient nutrients is required for a maximal response. Administration of only one nutrient may either unmask the concurrent deficiency or result in a blunted response.
