Vitamin B9 deficiency

Background

• Also known as folate, folic acid
• Necessary for normal erythropoiesis, purine and thymidylate synthesis, amino acids metabolism, and histidine metabolism
• Found in most fruits and vegetables
• Recommended daily intake: 400 mcg or 500-600mcg if pregnant or lactating
• Total body stores of folate enough to supply requirements for 2–3 mo
• Most common cause of deficiency is inadequate dietary intake, usually secondary to:
  • Chronic alcohol abuse
  • Anorexia
  • Inadequate or overcooked fruit/vegetable intake
• Other causes:
  • Decreased absorption
    • Tropical sprue
    • Drugs (phenytoin, sulfasalazine, trimethoprim-sulfamethoxazole
  • Increased requirement
    • Chronic hemolytic anemia
    • Pregnancy
    • Exfoliative skin disorders
  • Folate loss due to hemodialysis
  • Inhibition of reduction to active form (tetrahydrofolic acid) by methotrexate

Clinical Features

• Signs/symptoms of anemia which may be severe
• Glossitis
• Vague GI disturbances (e.g. anorexia, diarrhea)
• No neurologic features (unlike B12 deficiency)

Differential Diagnosis

Anemia

RBC Loss

• Hemorrhage

RBC consumption (Destruction/hemolytic)

• Hereditary
• Acquired
• Microangiopathic Hemolytic Anemia (MAHA)
• Autoimmune hemolytic anemia

Impaired Production (Hypochromic/microcytic)

• Iron deficiency
• Anemia of chronic disease
• Thalassemia
• Sideroblastic anemia

Aplastic/myelodysplastic (normocytic)

• Marrow failure
• Chemicals (e.g. ETOH)
• Radiation
• Infection (HIV, parvo)

Megaloblastic (macrocytic)

• Vitamin B12/folate deficiency
• Drugs (chemo)
• HIV

Evaluation

• CBC
  • Macrocytic anemia (MCV>100 fL)
  • RDW high
  • Hypersegmented neutrophils
• Red blood cell folate level < 150 ng/mL

Management

• Folate: up to 1mg IV/IM or PO daily
  • Maintenance: 0.4mg/day PO (non-pregnant/lactating) or 0.8mg/day PO (pregnant or lactating)

See Also

• Vitamin deficiencies
• Folic acid
• Anemia