Pellagra

Pellagra is a caused by nicotinic acid (niacin) deficiency. The classical features are the 3 D's - dermatitis, diarrhoea and dementia

Pellagra may occur as a consequence of isoniazid therapy (isoniazid inhibits the conversion of tryptophan to niacin) and it is more common in alcoholics.

Features

• dermatitis (brown scaly rash on sun-exposed sites - termed Casal's necklace if around neck)
• diarrhoea
• dementia, depression
• death if not treated