Folic Acid Deficiency

Snapshot

A 25-year-old woman presents to her obstetrician at 22-weeks pregnant. She had no previous prenatal care but denies any problems. She denies taking any vitamin supplements. She is doing well in her first pregnancy and finally came for prenatal care at the urging of her mother. She is notably pale. Bloodwork reveals megaloblastic anemia and she is started on folic acid supplementation immediately. However, she is counseled on the possible affects folic acid deficiency may have on the baby.

Introduction

Folic acid (or vitamin B9) is found in leafy green vegetables
Pathogenesis
- folic acid is absorbed in jejunum and ileum
  - used in tetrahydrofolate (THF) as coenzyme
  - important for DNA and RNA synthesis
  - small reserve pool in liver
  - see Vitamins topic
- causes megaloblastic anemia due to impaired DNA synthesis
Epidemiology
- most common vitamin deficiency in the US
- most common cause of megaloblastic anemia
- can manifest after 4 months (depleted storage from liver)
Associated conditions
- chronic hemolytic anemias
- alcoholism
- malabsorption
  - celiac disease
  - tropical sprue
- pregnancy
  - risk of neural tube defects in infant
- certain drugs (anti-folates)
  - phenytoin
methotrexate

Presentation

Evaluation

Peripheral blood smear
- hypersegmented lobes seen in neutrophils
- macrocytosis
Serum
- ↓ folic acid
- ↑ homocysteine
- NORMAL methylmalonic acid (MMA)
unlike in vitamin B12 deficiency, which has ↑MMA

Differential Diagnosis

Vitamin B12 deficiency
Pernicious anemia
Other causes of macrocytic anemia
- alcoholism
- hypothyroidism
- liver dysfunction
drugs

Treatment

Prognosis, Prevention, and Complications

Prognosis
- good with supplementation
Prevention
- folic acid supplementation, especially if chronically on drugs such as methotrexate
Complications
- neural tube defects in infant if deficient during pregnancy