A 42-year-old male construction worker from Uttar Pradesh presents with a 4-week history of dermatitis on sun-exposed areas (face, neck, hands), chronic diarrhea, and mood disturbance. On examination, he has a well-demarcated erythematous rash with scaling and lichenification in a glove-and-stocking distribution. Serum albumin is 2.8 g/dL. He reports a diet consisting mainly of polished rice and legumes. What is the most appropriate immediate management?

Explanation

## Clinical Diagnosis: Pellagra (Niacin Deficiency) This patient presents with the classic **4 Ds of pellagra**: **Dermatitis** (sun-exposed areas), **Diarrhea**, **Dementia** (mood disturbance), and **Death** (if untreated). The glove-and-stocking distribution of the rash and low serum albumin (indicating malnutrition) are pathognomonic. ## Why Oral Niacin is the Correct First Step **Key Point:** Pellagra is a medical emergency but responds rapidly to oral niacin supplementation. Treatment should begin immediately based on clinical diagnosis—do not delay for confirmatory serum levels. **High-Yield:** Niacin (vitamin B3) deficiency is endemic in populations consuming polished rice without legume fortification. The diagnosis is primarily **clinical**; serum niacin levels are not routinely measured and should not delay treatment initiation. **Mnemonic:** **PEL**agra = **P**olished rice, **E**nzyme deficiency (NAD/NADP), **L**ow tryptophan conversion ## Niacin Dosing and Route Selection | Route | Dose | Frequency | When to Use | Advantage | |-------|------|-----------|-------------|----------| | **Oral (nicotinic acid)** | 500 mg | TDS (1500 mg/day) | Mild-moderate pellagra, good GI absorption | First-line; rapid clinical response in 24–48 hrs | | **IV (nicotinamide)** | 100 mg | Daily × 5 days | Severe pellagra, severe malnutrition, poor oral intake | Reserved for critical cases; not needed here | | **Oral (nicotinamide)** | 500 mg | TDS | Alternative to nicotinic acid | Avoids flushing; slower onset | **Clinical Pearl:** Oral niacin produces flushing and pruritus (prostaglandin-mediated vasodilation) but this is not a contraindication—it indicates bioavailability. Nicotinamide avoids flushing but is less effective for acute pellagra. ## Management Algorithm ```mermaid flowchart TD A[Clinical suspicion of pellagra]:::outcome --> B{Dermatitis + diarrhea + neuropsych signs?}:::decision B -->|Yes| C[Start oral niacin 500 mg TDS immediately]:::action B -->|No| D[Consider other diagnoses]:::action C --> E[Reassess at 24-48 hours]:::outcome E -->|Improvement| F[Continue oral niacin; add dietary counseling]:::action E -->|No improvement| G[Consider IV niacin or comorbidities]:::action ``` ## Why Serum Niacin Levels Are Not Required **Warning:** Waiting for serum niacin confirmation (option 1 says "after confirming") is a common trap. Serum niacin levels are: - Not routinely available in most Indian labs - Not sensitive or specific for tissue niacin status - Clinically unnecessary when the diagnosis is clear (dermatitis + diarrhea + malnutrition + dietary risk) Treat based on **clinical presentation**, not laboratory confirmation.