[Pellagra].

Abstract

Pellagra is a systemic disturbance caused by a cellular deficiency of niacin, resulting from inadequate dietary nicotinic acid and/or its precursors, the essential amino-acid tryptophan. In Europe and North America cases of pellagra are rarely encountered, but in some developing countries this disease is frequent, and is the most frequent clinical feature of nutritional deficiency of adult. The principal causes of pellagra are: nutritional niacin deficiency; chronic alcoholism; gastro-intestinal malabsorption; some medications (5-fluoro-uracil, isoniazid, pyrazinamide ehtionamide, 6-mercaptopurine, hydantoins, phenobarbital and chloramphenicol). The diagnosis of pellagra is based on the patient's history and the presence of "3 D syndrome": dermatitis, diarrhea, and dementia. The dermatitis caused by pellagra is a bilaterally symmetrical erythema at the sites of solar exposure. The dermatitis begins in the form of an erythema with acute or intermittent onset gradually changing to an exsudative eruption on the dorsa of the hand, face, neck, and chest with pruritus and burning. Acute dermatitis of pellagra resembles sunburn in the first stages, sometimes with vesicles and bullae. The gastro-intestinal disturbances are: anorexia, nausea, epigastric discomfort and chronic or recurrent diarrhea. Anorexia and malabsorbative diarrhea lead to a state of malnutrition and cachexia. Stools are typically watery, but occasionally can be bloody and mucoid. Neuropsychologic manifestation included photophobia, asthenia, depression, hallucinations, confusions, memory loss and psychosis. As pellagra advances, patient become disoriented, confused and delirious; then stuporous and finally die. Pathological changes in the skin is non-specific, there are no chemical tests available to definitively diagnose pellagra. However low levels of urinary excretion of N-methylnicotinamide and pyridone indicates niacin deficiency. The treatment of pellagra consisted to exogenous administration of niacin or nicotinamide cures. Topical management of skin lesions with emollients may reduce discomfort. The therapy should also include other B vitamins, zinc and magnesium as well as a diet rich in calories. The prevention is based in the nutritional education (food sources of niacin: eggs, bran, peanuts, meat, poultry, fish, red meat, legumes and seeds), and the eviction of alcohol.