Download Folic acid

Megaloblastic anemia
Due to B12 and folate deficiencies.
Folic acid deficiency
Sources and requirements:
•Known as folate or petroyl glutamic acid.
•Water soluble.
•Present in a variety of foods (green leafy vegetables, fruits and
liver and kidney).
•Heat labile vitamin.
•Dietary intake for adults 30µg/kg per day.
Structure:
Folic acid
•Made of three components.
•Folic acid derived from diet
is not biologically active.
•Once absorbed through the
duodenum it hydrolyzed,
reduced and methylated to
form MTHF.
•Other form THF
(biologically active).
Pterdine
Amino benzoic acid
Gultamic acid
(Poly Glutamic Acid)
Absorption and metabolism
Intestine
Diet
Poly glutamic acid
Poly glutamate
Folate reductase
Glu
Mono glutamate
CH3THF
Methyl Tetrahydrfolate
DNA
Synthesis
cTHF
Glu
THF
Homocysteine
Methionine
CH3THF
CH3THF
Tissue cell
Circulation
Causes of folic acid deficiency
1. The main causes is decrease dietary intake:
• Old age,
• Alcoholism
• Chronic diseases.
2. Mal absorption:
• Tropical sprue.
• Gluten-sensitive enteropathy.
3. Increase requirements:
• Pregnancy.
• Infancy.
• Malignancy.
4. Drugs:
• Methotrexate, oral contraceptives.
Laboratory diagnosis of megaloblastic anemia
•
CBC
Low hemoglobin level and elevated MCV.
•
PB morphology
Macrocytosis, macroovalocytes and hyper segmented
neutrophils.
•
Chemical testing
Serum folic acid Low (RC FA)
•
BM
Hyper cellular BM.
Megaloblastic picture (large cells with increased RNA per
DNA unit.
Nuclear chromatin appears
loose and less mature than
nuclear chromatin of normal
red cells.
Megakaryocytes may be
hypersegmented.
Giant bands and hypersegmented
polymorphonuclear neutrophils
are common.
Differential Lab Diagnosis of
Megaloblastic anemia
High MCV
>98 fl
Check smear for macrocytes and hyper segmented neutrophils
Yes
Serum B12
Serum folate
Red cell folate
NO
All normal
Alcoholism
Liver diease
?Hematologic diease
Decreased level of B12
Decreased red cell folate
Anti-IF antibodies
Folic acid deficiency
Anti-IF antibodies
No
Yes
Schilling test
Abnormal
corrected
with IF
Abnormal
Not corrected
IF
Normal
Dietary deficiency
P.A.
Mal absorption