Epidemiology

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Etiology

• Malnutrition
• Heavy drinking
• Chronic renal failure
• Chronic hepatitis
• Drug interactions
  • Isoniazid
  • Oral contraceptives

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Pathophysiology

Active form: pyridoxal phosphate (PLP)

Vitamin B6 functions

• PLP is a coenzyme for the following reactions:
  • Transamination (e.g., AST and ALT)
  • Decarboxylation
  • Amino acid metabolism
  • Glycogenolysis (glycogen phosphorylase)
• Involved in the synthesis of:
  • Heme, see Heme synthesis
  • Histamine
  • Niacin
  • Gluthathione
  • Cystathionine
  • Neurotransmitters, including:
    • Serotonin
    • Dopamine
    • Epinephrine
    • Norepinephrine
    • GABA

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Clinical features

• Cheilosis, glossitis, stomatitis
• Sideroblastic anemia: Vitamin B6 deficiency causes heme synthesis dysfunction with impaired transfer of iron to hemoglobin, which ultimately leads to iron accumulation in RBCs.
• Irritability, seizures, peripheral neuropathy
• Seborrheic dermatitis

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Diagnostics

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Treatment

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