Traditionally caused by consuming a diet mainly composed of corn and maize.
Severe deficiency leads to pellagra, which is characterized by dermatitis, dementia, diarrhea, and eventually death.
Lean meat, poultry, fish, and peanuts are rich in vitamin B3 (niacin); milk and eggs are rich sources of tryptophan, the precursor of niacin.
Deficiency of vitamins B2 (riboflavin) and/or B6 (pyridoxine) reduces the synthesis of niacin from tryptophan and may lead to secondary vitamin B3 deficiency.
Rare in developed countries, although there are still outbreaks in Africa, India, and China, particularly in refugees and displaced people.
In developed countries, deficiency is most commonly associated with chronic alcohol use disorder, gastrointestinal malabsorption, and certain medications (e.g., isoniazid).
As the symptoms of mild vitamin B3 deficiency are similar to those of other B vitamin (e.g., B2 and B6) deficiencies that may coexist, the cause may be difficult to define.
Treatment with niacinamide will alleviate the cutaneous and many neurologic symptoms within 48 hours.
Vitamin B3, also referred to as niacin, is the generic term for nicotinic acid, its amide (nicotinamide or niacinamide), and their biologically active derivatives. It is also found in the form of the pyridine nucleotide coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADPH). These are essential in all cells for energy production, metabolism, and DNA repair. Severe deficiency results in pellagra, which is a combined deficiency of both niacin and its precursor, tryptophan. The symptoms of deficiency are primarily dermatitis, diarrhea, and dementia. Death results if the condition is untreated.
History and exam
Key diagnostic factors
- insomnia, depression, or memory loss
- intermittent stupor
- hallucinations or delirium
- peripheral neuropathy
- oppositional hypertonus or myoclonus
- cogwheel rigidity
- primitive reflexes
- nausea, vomiting, or diarrhea
- glossitis, cheilitis, or stomatitis
Other diagnostic factors
- anxiety or paranoia
- anorexia, weight loss, or cachexia
- angular palpebritis
- chronic alcohol use disorder
- vitamin B2 (riboflavin) deficiency
- vitamin B6 (pyridoxine) deficiency
- eating disorders
- Hartnup disease
- carcinoid syndrome
- antituberculous drugs
- Crohn disease
- HIV infection
- copper deficiency
- certain drugs
- pregnancy and lactation
- age >65 years
- Alzheimer dementia
- Parkinson disease
1st investigations to order
- serum tryptophan
- urinary N-methylnicotinamide
- urinary N-methyl-2-pyridone-5-carboxamide
- urinary 2-pyridone/N-methylnicotinamide ratio
- skin biopsy
- photosensitivity testing
- serum albumin
- serum protein
Investigations to consider
- serum total iron
- iron-binding capacity
- transketolase activity
- thiamine pyrophosphate (TPP)
- riboflavin coefficient
- serum pyridoxal-5-phosphate
- serum cyanocobalamin
- serum folic acid
- red cell folic acid
- stool exam
- neutral aminoaciduria
- serum serotonin
- platelet serotonin
- urinary 5-hydroxyindoleacetic acid
- HIV antibodies
- mental state exam
asymptomatic (marginal deficiency)
- Evaluation of the nutritional status and growth in refugee children during the domestic medical screening examination
- The management of nutrition in major emergencies
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