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