pellagra (niacin deficiency, vitamin B3 deficiency)

Introduction

The clinical syndrome resulting from deficiency of niacin.

Etiology

• malnutrition
  • dietary restriction
  • alcoholism

Epidemiology

• homeless
• rare in the U.S.

Pathology

• diffuse inflammation & atrophy of gastrointestinal mucosa results in non-bloody diarrhea

Clinical manifestations

• photosensitivity:
  • recurring pruritic erythema on sun-exposed areas of skin
  • exfoliative dermatitis
  • edema, thickening, dryness, roughness, hyperpigmentation, & eruption with desquamation may occur
• muscle weakness
• gastrointestinal manifestations in 50%
  • glossitis, stomatitis, dyspepsia
  • intractable non-bloody diarrhea
• backpain
• psychiatric manifestations develop late (40%)
  • irritability
  • anxiety
  • delusions
  • hallucinations
  • apathy, melancholia
  • fatigue
  • depression
• neurologic manifestations
  • spastic paresis
  • myelitis
  • peripheral neuropathy
  • idiocy, cognitive impairment, dementia

Laboratory

• serum niacin is low or undetectable

Management

• niacin replacement therap
  • 300 mg/day in divided doses for severeal weeks
• multivitamin & mineral supplementation prudent as patients are often deficient in several essential nutrients
• prognosis
  • response time varies according severity, but clinical improvement may be seen within a few days

More general terms

• vitamin B deficiency

Additional terms

• nicotinic acid (niacin, vitamin B3, Niaspan)