Niacin (Vitamin B3) deficiency

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Niacin (Vitamin B3) deficiency

Nutrition & Biochemistry

Nutrition & Biochemistry

Vitamin K deficiency

Vitamin D deficiency

Excess Vitamin A

Excess Vitamin D

Folate (Vitamin B9) deficiency

Niacin (Vitamin B3) deficiency

Vitamin B12 deficiency

Vitamin C deficiency

Wernicke-Korsakoff syndrome

Iodine deficiency

Zinc deficiency

Fat-soluble vitamin deficiency and toxicity: Pathology review

Zinc deficiency and protein-energy malnutrition: Pathology review

Water-soluble vitamin deficiency and toxicity: B1-B7: Pathology review

Carbohydrates and sugars

Fats and lipids

Essential fructosuria

Hereditary fructose intolerance

Pyruvate dehydrogenase deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Lactose intolerance

Glycogen storage disease type I

Glycogen storage disease type II (NORD)

Glycogen storage disease type III

Glycogen storage disease type IV

Glycogen storage disease type V

Metachromatic leukodystrophy (NORD)

Gaucher disease (NORD)

Niemann-Pick disease types A and B (NORD)

Niemann-Pick disease type C

Fabry disease (NORD)

Tay-Sachs disease (NORD)

Mucopolysaccharide storage disease type 1 (Hurler syndrome) (NORD)

Mucopolysaccharide storage disease type 2 (Hunter syndrome) (NORD)

Hartnup disease

Ornithine transcarbamylase deficiency

Phenylketonuria (NORD)

Cystinuria (NORD)

Maple syrup urine disease

Abetalipoproteinemia

Familial hypercholesterolemia

Hypertriglyceridemia

Disorders of carbohydrate metabolism: Pathology review

Disorders of fatty acid metabolism: Pathology review

Dyslipidemias: Pathology review

Glycogen storage disorders: Pathology review

Lysosomal storage disorders: Pathology review

Disorders of amino acid metabolism: Pathology review

Citric acid cycle

Electron transport chain and oxidative phosphorylation

Gluconeogenesis

Glycogen metabolism

Pentose phosphate pathway

Physiological changes during exercise

Amino acid metabolism

Nitrogen and urea cycle

Fatty acid synthesis

Fatty acid oxidation

Ketone body metabolism

Cholesterol metabolism

Lesch-Nyhan syndrome

Orotic aciduria

Mitochondrial myopathy

Flashcards

Niacin (Vitamin B3) deficiency

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Questions

USMLE® Step 1 style questions USMLE

0 of 2 complete

A 15-year-old boy is brought in by his parent to the clinic for evaluation of a skin rash over his chest and arms for the past 2 weeks. The patient has noticed that the rash becomes pruritic and painful to touch when he goes outside to play soccer. He also complains of loose stools over the last week. Three months ago, he was diagnosed with latent tuberculosis and was started on isoniazid. He and his family immigrated from India 9 months ago. Temperature is 37.0°C (98.6°F), pulse is 74/min, respirations are 16/min, and blood pressure is 115/75 mmHg. BMI is 20 kg/m2. Physical examination reveals scaly erythematous patches and hyperpigmentation of the arms, chest and skin below the knees. Motor strength is 5/5 in all four extremities. Sensation is intact throughout. Which of the following amino acids is a precursor of the vitamin that is most likely deficient in this patient?

Key Takeaways

Niacin or vitamin B3 is important for the proper functioning of the nervous system and the metabolism of carbohydrates, fats, and proteins.

Deficiency in niacin presents with weakness, fatigue, loss of appetite, and skin problems such as rashes or hyperpigmentation. Severe niacin deficiency can lead to a condition called pellagra, which is characterized by diarrhea, dermatitis, dementia, and death.

Niacin deficiency is commonly caused by inadequate intake of niacin or tryptophan, an amino acid that the body can convert into niacin. The treatment is usually increasing the intake of niacin through diet or supplements.