Pellagra: Difference between revisions
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==Background== | ==Background== | ||
Pellagra is the deficiency of Niacin (Vitamin B3). | *Pellagra is the deficiency of Niacin (Vitamin B3). | ||
*Niacin is an important factor for the production of NADH and NADPH, which are important for redox reactions. | |||
**Deficiency therefore affects tissues with high turnover, including skin, GI tract and brain | |||
*Niacin is either consumed in the diet or converted from tryptophan by the hepatic kynurenine pathway in the liver. | *Niacin is either consumed in the diet or converted from tryptophan by the hepatic kynurenine pathway in the liver. | ||
*Neurological symptoms can also be exacerbated by supplementation by other B vitiamins, particularly B1, B2, B6, and B12. Mechanism is unknown but may be secondary to the increased demand of NAD. | *Neurological symptoms can also be exacerbated by supplementation by other B vitiamins, particularly B1, B2, B6, and B12. Mechanism is unknown but may be secondary to the increased demand of NAD. | ||
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==Clinical Features== | ==Clinical Features== | ||
[[File:Casal's_necklace.png|thumb|Casal's Necklace in a case of isoniazid-induced pellagra.]] | [[File:Casal's_necklace.png|thumb|Casal's Necklace in a case of isoniazid-induced pellagra.]] | ||
''Niacin deficiency classically causes the 4 D's: Dermatitis, Diarrhea, Dementia and Death.'' | |||
* Skin photosensitivity and rash. Erythematous and scaly. May be mistaken for sunburn. | * Skin photosensitivity and rash. Erythematous and scaly. May be mistaken for sunburn. | ||
**secondary to UV damage and decreased repair | **secondary to UV damage and decreased repair | ||
Revision as of 12:26, 7 February 2016
Background
- Pellagra is the deficiency of Niacin (Vitamin B3).
- Niacin is an important factor for the production of NADH and NADPH, which are important for redox reactions.
- Deficiency therefore affects tissues with high turnover, including skin, GI tract and brain
- Niacin is either consumed in the diet or converted from tryptophan by the hepatic kynurenine pathway in the liver.
- Neurological symptoms can also be exacerbated by supplementation by other B vitiamins, particularly B1, B2, B6, and B12. Mechanism is unknown but may be secondary to the increased demand of NAD.
Drugs that inhibit niacin production
- Azathioprine
- Chloramphenicol
- Ethionamide
- 5-Fluorouracil
- Isoniazid
- 6mercaptopurine
- Pyrazinamide
Conditions that decrease niacin GI absoprtion
- Colitis
- Celiac disease
- Crohn's disease
- Ulcerative colitis
- Cirrhosis
- Gastrectomy patients
Clinical Features
Niacin deficiency classically causes the 4 D's: Dermatitis, Diarrhea, Dementia and Death.
- Skin photosensitivity and rash. Erythematous and scaly. May be mistaken for sunburn.
- secondary to UV damage and decreased repair
- "Casal's Necklace." Reddish rash surrounding the neck, and on the hands and feet. This is a photosensitivity rash in the exposed areas of the neck. Originally described by Gaspar Casal in 1735.
- GI symptoms
- secondary to decreased cell turnover
- Neurological symptoms
- "Pellagra encephalopathy," depression, anxiety, altered mental status, hallucinations, delusions, affective disorders, cognitive dysfunction.
- Niacin deficiency is often associated with chronic alcohol use secondary to nutritional deficiency and malabsorption.
Differential Diagnosis
Diagnosis
Management
Niacin supplementation.
Disposition
See Also
External Links
References
- Badaway, Abdulla. “Pellagra and Alcoholism: a biochemical perspective.” Alcohol and alcoholism 2014; vol 49, No 3, pages 238-250
- Lopez, Marta, et al. “Pellagra Encephalopathy in the context of alcoholism: review and case report.” Alcohol and alcoholism. Vol 49. No 1. pages 38-41. 2014.