A young adult vegetarian develops a hyperpigmented, scaly rash symmetrically over sun-exposed skin of the face and hands, along with glossitis and episodic diarrhoea. Treatment should be supplementation with:

• A Nicotinamide ✓
• B Pyridoxine
• C Riboflavin
• D Biotin

Explanation

This is pellagra, caused by niacin deficiency, classically remembered as dermatitis, diarrhoea, and dementia, and treated with nicotinamide. Niacin can be synthesised endogenously from tryptophan (about 60 mg tryptophan yields 1 mg niacin), so maize-based or low-tryptophan vegetarian diets predispose. Riboflavin deficiency causes angular stomatitis and cheilosis without the photosensitive dermatitis, which kills option C. Pyridoxine deficiency causes sideroblastic anaemia and neuropathy, and biotin deficiency causes alopecia and neurological signs.

Reference: Harper's Illustrated Biochemistry, 31st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.