Makindo Medical Notes

⚠️ The classic mnemonic for pellagra = the four Ds: Dermatitis, Diarrhoea, Dementia → Death. 📜 Historically, it was thought to be an infectious disease until the early 20th century.

ℹ️ About

• 🔬 Pellagra = deficiency of niacin (Vitamin B3) or its precursor tryptophan.
• 🍽️ Results from inadequate dietary intake or impaired metabolism.
• 📖 Name derived from Italian “pelle agra” = “rough skin”.
• 🧪 First B-vitamin identified was thiamine, but pellagra highlights niacin’s role in metabolism.

⚠️ Causes / Risk Factors

• 🌽 Maize/corn-based diets (low in tryptophan & niacin unless treated with alkali)
• 🍷 Alcoholism, anorexia, severe malnutrition
• 🧬 Malabsorption & chronic GI disease
• 💊 Drugs: Isoniazid (inhibits conversion of tryptophan → niacin)
• 🏥 Hypercatabolic states (infection, adrenal phaeochromocytoma, malignancy)

🧬 Aetiology

• Niacin is required for synthesis of NAD and NADP, essential cofactors in oxidative metabolism.
• Critical for energy production in all living cells.
• Some hepatic storage exists but limited.
• 💉 Pharmacological niacin lowers LDL & VLDL cholesterol.

📂 Types

• 🥗 Primary pellagra: Dietary deficiency of niacin/tryptophan.
• 🧪 Secondary pellagra: Due to impaired absorption, metabolism, or increased demand (alcoholism, isoniazid therapy, chronic illness).

💊 Pearl: Pellagra is a recognised complication of isoniazid therapy, which blocks tryptophan → niacin conversion.

🩺 Clinical Features

• 👅 Glossitis, angular stomatitis, pigmented & scaling rash (esp. sun-exposed areas)
• 🍽️ Anorexia, irritability, abdominal pain, diarrhoea, vomiting
• 🩸 Mucosal involvement: vaginitis, oesophagitis
• 🌞 Dermatitis: photosensitive rash, Casal’s necklace around the neck (pathognomonic)
• 🧠 Neuro: irritability → depression → progressive dementia
• ☠️ Untreated disease progresses to death

🔎 Investigations

• 🩸 Anaemia (often microcytic hypochromic)
• ⬆️ Hyperhomocysteinaemia (due to impaired NAD metabolism)
• 📉 Low serum niacin levels (confirmatory)

💊 Management

• 💊 Oral nicotinamide supplementation (dramatic clinical improvement in days–weeks)
• 🥗 Optimise overall nutrition: protein, vitamins, and minerals
• 🌽 Public health: maize flour fortification with nicotinamide for long-term prevention

📌 Exam Pearl: Pellagra = think of “corn diet + 4Ds”. In clinical practice, always ask about alcohol use, nutrition, and isoniazid therapy.

📚 References

• WHO: Pellagra – Prevention and Control in Major Emergencies