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Updated: Dec 16 2021

Folic Acid Deficiency

Images
https://upload.medbullets.com/topic/120228/images/differential for anemia - moises d.jpg
https://upload.medbullets.com/topic/120228/images/hypersegmented-neutrophil-2..jpg
  • Snapshot
    • A 50-year-old alcoholic man presents to the hospital in a florid alcohol withdrawal. He confabulates and trembles uncontrollably. He is started on supportive therapy for now. An alcohowal withdrawal score is done regularly to assess for the need for medical therapy. In the meantime, bloodwork comes back with megaloblastic anemia and increased homocysteine and normal methylmalonic acid. He is immediately started on folic acid supplementation.
  • Introduction
    • Folic acid (or vitamin B9) is found in leafy green vegetables
    • Associated conditions
      • chronic hemolytic anemias
      • malnutrition
        • alcoholism
        • elderly
        • psychiatric comorbidity
      • pregnancy
        • increased folate requirement
      • malabsorption
        • celiac disease
        • tropical sprue
      • pregnancy
        • risk of neural tube defects in infant
      • certain drugs (anti-folates)
        • phenytoin
        • methotrexate
        • trimethoprim
  • Epidemiology
    • Most common vitamin deficiency in the US
    • Most common cause of megaloblastic anemia
    • Can manifest after 4 months (depleted storage from liver)
  • ETIOLOGY
    • Pathogenesis
      • folic acid is absorbed in duodenum and jejunum
        • used in tetrahydrofolate (THF) as coenzyme
        • important for DNA and RNA synthesis
        • small reserve pool in liver
      • causes megaloblastic anemia due to impaired DNA synthesis
  • Presentation
    • Symptoms
      • no neurological symptoms (unlike in B12 deficiency)
      • anemia
        • fatigue
        • weakness
        • shortness of breath
    • Physical exam
      • glossitis
      • pallor
  • Evaluation
    • Peripheral blood smear
      • hypersegmented lobes seen in neutrophils
      • macrocytosis
      • basophilic stippling
    • Serum
      • ↓ folic acid
      • ↑ homocysteine
      • NORMAL methylmalonic acid (MMA)
        • unlike in vitamin B12 deficiency, which has ↑MMA
      • ↓ reticulocyte count
      • may see pancytopenia due to destruction of abnormal cells
      • increased MCV
        • folate is more readily depleted than B12
    • Also test for B12 deficiency and TSH (to rule out hypothyroidism)
  • Differential
    • Vitamin B12 deficiency
    • Pernicious anemia
    • Other causes of macrocytic anemia
      • alcoholism
      • hypothyroidism
      • liver dysfunction
      • drugs
  • Treatment
    • Folic acid supplementation
    • Eat a more balanced diet
      • fruits and vegetables
    • Prevention
      • folic or folinic acid supplementation, especially if chronically on drugs such as methotrexate
  • Complications
    • Neural tube defects in infant if deficient during pregnancy
    • In the setting of a B12 deficiency, the anemia can correct with aggressive folate supplementation but the patient will still be at risk for neurological complications of B12 deficiency including peripheral neuropathy and posterior column defects due to deficiencies in myelin production
  • Prognosis
    • Good with supplementation
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