Pellagra

Pellagra is a disease caused by a deficiency of niacin, also known as vitamin B3, or its amino acid precursor, tryptophan. It primarily manifests as a triad of symptoms - dermatitis, diarrhea, and dementia. If left untreated, it can potentially be fatal.

Pellagra

Pathophysiology of Pellagra

Niacin is an essential nutrient that plays a critical role in cellular metabolism. It serves as a precursor to nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), both of which are necessary for various metabolic reactions and cellular processes.

When the body lacks sufficient niacin or tryptophan, these processes are disrupted, leading to the characteristic symptoms of pellagra. This condition is most commonly seen in regions where maize (which contains niacin in a form that is not bioavailable) is a dietary staple and protein intake, particularly of tryptophan-rich foods, is low.

Clinical Presentation of Pellagra

The classic presentation of pellagra is often summarized as the "four D's": dermatitis, diarrhea, dementia, and death.

• Dermatitis: The skin rash typically associated with pellagra is symmetrical, scaly, and occurs on areas of the body exposed to sunlight or friction such as hands, feet, and neck (referred to as Casal's necklace).
• Diarrhea: Gastrointestinal symptoms can be diverse and include diarrhea, nausea, vomiting, and abdominal pain.
• Dementia: Neurological symptoms range from irritability and fatigue to advanced cognitive decline and psychiatric symptoms.
• Death: If left untreated, pellagra can lead to death, typically due to multiorgan failure.

Diagnosis and Treatment of Pellagra

The diagnosis of pellagra is usually based on clinical signs and symptoms along with dietary history. Laboratory testing can be performed to measure niacin levels, but these are not routinely done.

Pellagra is primarily treated by replenishing the body's niacin supply. This is typically achieved through oral niacin supplements and promoting a balanced diet that includes niacin-rich foods, such as lean meats, fish, and legumes. In severe cases or when oral administration is not feasible, niacin can be given intravenously.

Prevention and Prognosis

Prevention strategies for pellagra focus on dietary diversification and fortification, increasing intake of niacin and tryptophan-rich foods, and educating populations at risk about the disease.

The prognosis of pellagra is generally good with prompt diagnosis and treatment. However, in severe cases or if treatment is delayed, irreversible neurological damage may occur.

Conclusion

Pellagra is a preventable disease that continues to affect populations with limited diets or malabsorption conditions. Understanding its causes, presentation, and management strategies is essential for healthcare professionals, especially those working in global and public health contexts.

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References

• Stratigos JD, Katsambas A. Pellagra: a still existing disease. The British Journal of Dermatology. 1977;96(1):99-106.
• Hegyi J, Schwartz RA, Hegyi V. Pellagra: dermatitis, dementia, and diarrhea. International Journal of Dermatology. 2004;43(1):1-5.
• Brown TM. Pellagra: an old enemy of timeless importance. Psychosomatics. 2010;51(2):93-97.