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Pathophys and Cause ⬇

Cause:Niacin (nicotinic acid) deficiency, esp in populations dependent on corn (maize), which lacks tryptophan

Pathophys:Dietary tryptophan deficiency

Signs and Symptoms ⬆ ⬇

Sx:Diarrhea, dementia/depression/delirium, dermatitis

Si:Casal's necklace (neck erythema, scales, and hyperpigmentation)

Complications ⬆ ⬇

r/o photosensitive dermatitis in gastric bypass patients (Nejm 2006;354:1614)

Lab and Xray ⬆ ⬇

Lab:

Urine: N-methylnicotinamide, a normal metabolite of niacin, undetectable

Treatment ⬆

Rx:50-300 mg niacin po qd, balanced diet