It is usual to associate megaloblastic anemia with folate or cobalamin deficien cies. However, this notion, even if true in most cases, is too restricted. Megalo blastosis in blood may also be observed in blood diseases without vitamin defi ciency, and also after treatment with certain antineoplastic agents; in these con ditions, the mechanisms vary with the etiology. On the other hand, folate or cobalamin deficiency may induce various clinical or biochemical disturbances without - as yet - macrocytic megaloblastic anemia. That the biochemical basis of megaloblastosis is the same in folate and cobal amin deficiencies is due to the close metabolic interrelationships between thse two vitamins. However, the role of cobalamin deficiency in folate metabolism is still a matter of debate. Morphological abnormalities such as macrocytosis in peripheral blood and megablastosis in bone marrow, long considered to be the best indices of vitamin deficiency, are not always constant. Indeed, the improved diagnostic methods often lead to an early diagnosis of deficiency before the appearance of the usual hematological abnormalities.

1 Biochemical Basis of Megaloblastosis

2 Diagnosis of Megaloblastic Anemia
3 Cobalamin-Folate Interrelations
4 The Proteins of Transport of the Cobalamines
5 Cobalamin Absorption and Acquired Forms of Cobalamin Malabsorption
6 Current Gastroenterologic Aspects of Pernicious Anemia
7 Cobalamin Malabsorption in Exocrine Pancreatic Insufficiency in Adults and Children
8 Making Sense of Laboratory Tests of Folate Status: Folate Requirements to Sustain Normality
9 Prevalence of Folic Acid Deficiency in the French Population
10 Effects of some Drugs and Alcohol on Folate and Cobalamin Metabolism
11 Neuropsychiatrie Illness and Deficiency of Vitamin B12 and Folate
12 Folate Deficiency During Pregnancy and Lactation
13 Folic Acid Deficiency in Developing Nations
14 Folate Deficiency in Geriatric Patients
15 Folate Deficiency in Intensive Care Patients
16 Inherited Defects of Folate Metabolism
17 The Relationship Between Biopterin and Folate Metabolism
18 Inherited Disorders of Colbalamin Metabolism
19 Transport of Folate Compounds by Hematopoietic Cells
20 Methotrexate and 5-Fluorouracil: Cellular Interactions with Folates
21 Methotrexate Pharmacokinetic Studies: Their Clinical Use.