Biochemistry:

Tryptophan 

• converted into serotonin → melatonin
• Converted into niacin (catalyst B2, B6) → Niacin has two form 

1. Nicotinic acid → used as lipid lowering agent
2. Nicotinamide →NAD, NADP → REDOX reaction 

Description of photograph:

• Erythematous, hyperpigmented, scaly rashes on chest, face, arm
• alopecia, cheilosis

1. Causes of Niacin Deficiency

1. Drug: INH (reduce vit B6)
2. Carcinoid syndrome →tryptophan consumed for excessive serotonin synthesis
3. Hartnup syndrome → decreased absorption of several amino acid including tryptophan 
4. Alcoholics
5. Chronic small intestinal disease

1. Mention 3 history:

• Diet history, oral sore (glossitis), alcohol
• Diarrhea, Dementia (forgetfulness), insomnia
• H/O bariatric surgery
• Drug history: INH 

D/D:

1. Photodermatitis, Zinc deficiency
2. Contact dermatitis, Drug Eruption
3. PCT, SLE, Seborrheic dermatitis

Investigation:

1. Mention one drug for treatment with dose.

• Nicotinamide 100 mg TDS oral/IV