Niacin (nicotinic acid) deficiency results in a clinical syndrome termed pellagra ("rough skin").


Classic description of clinical findings - the 4 D's:

(1) diarrhea

(2) dermatitis

(3) dementia

(4) death


Mucosal changes in GI and GU tracts:

(1) swelling and soreness of the tongue and mouth with erythema (stomatitis)

(2) inflammation and erythema of mucosal surfaces (esophagitis, gastritis, urethritis, proctitis, vaginitis)

(3) diarrhea


Skin changes:

(1) symmetric pigmented rash with scaling and hyperkeratosis, which is worse in areas of sun exposure or trauma

(2) "necklace" lesion of Casal


Neurological changes:

(1) anxiety and depression

(2) insomnia

(3) headaches

(4) tremulous movements or rigidity of limbs

(5) loss of tendon reflexes, numbness and paresthesias in limbs

(6) dementia with disorientiation and hallucinations

(7) delirium


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