Vitamins

Niacin Deficiency

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Niacin Deficiency, Pellagra

  • See Also
  1. Vitamin B3 (Niacin)
  • Causes
  1. Primary Pellagra
    1. Inadequate Niacin or Tryptophan intake
  2. Secondary Pellagra (conditions interfering with absorption or metabolism or tryptophan or Niacin)
    1. Anorexia Nervosa
    2. Chronic Diarrhea
    3. Chronic Alcoholism
    4. Chronic colitis or ileitis
    5. Cirrhosis
    6. Hartnup Disease
    7. HIV Infection
    8. Malignant Carcinoid Tumor
    9. Medications
      1. Isoniazid (Niacin analog)
      2. Pyrazinamide
      3. Phenobarbitone
      4. 6-Mercaptopurine
      5. Fluorouracil
      6. Phenytoin
      7. Azathioprine
  • Pathophysiology
  1. Results in decreased NAD production
  • Symptoms
  1. Abdominal Pain
  2. Anorexia
  3. Fatigue
  4. Nausea or Vomiting
  5. Watery Diarrhea (Steatorrhea)
  6. Constipation
  • Signs
  • Classic Triad
  1. Diarrhea
  2. Dermatitis
  3. Dementia
  • Signs
  • Dermatitis
  1. May be absent despite neurologic changes (esp. chronic Alcoholism)
  2. Early (wet Pellagra)
    1. Sunburn-like skin dermatitis (erythema in sun exposed areas progresses to overlying vessicles or bullae)
  3. Later
    1. Scaly, symmetric red-brown Skin Discoloration involving face, neck (casal necklace), extensor hands/Forearms
    2. Dull red discoloration of nose with yellow Scaling
  4. Other skin and mucosal findings
    1. Alopecia
    2. Beefy red, smooth Glossitis
    3. Edema
  • Signs
  • Neurologic changes
  1. Ataxia
  2. Confusion or Memory Loss
  3. Major Depression
  4. Photophobia
  5. Peripheral Neuropathy
  • Labs
  1. Avoid lab testing (treat empirically based on symptoms, signs)
  2. Serum Levels (e.g. Niacin, tryptophan) are typically unreliable
  3. Urine metabolites (e.g. N-methylnicotinamide, 2-pyridone) are unreliable
  • Management
  1. Precautions
    1. Replacement of other B Vitamins without B3 replacement may exacerbate pellegra encepholopathy
  2. Vitamin B3 replacement
    1. Observe for rapid improvement in symptoms after starting replacement
    2. Initial
      1. Niacinamide 50 mg orally every 6 hours until major signs and symptoms resolve
    3. Next
      1. Niacinamide 50 mg orally every 8-12 hours until skin lesions resolve
  • Complications
  1. Dementia
  2. Cardiomyopathy
  • References
  1. Jhun et al. in Herbert (2016) EM:Rap 16(9): 8-10
  2. Rendon et al. (2017) Crit Dec Emerg Med 31(6): 15-21
  3. Ghosh (2013) Am Fam Physician 88(7):457-458 [PubMed]