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Riboflavin (Vit B2)

  1. Riboflavin a yellow fluorescent water soluble substance is stable to heat Q and acid but is destroyed by light Q and alkali
  2. Coenzymes FMN, FAD takes part in Krebs’ cycle, synthesis of fatty acid, oxidation of fatty acid and electron transport.
  3. Riboflavin is essential for growth and tissue respiration.  

Clinical manifestation of deficiency

  1. Cheilosis, glositis, Angular stomatitis Q, keratitis, photophobia, marked corneal vascularization and seborrheic dermatitis
  2. Normocytic normochromic anemia with Dome marrow hypoplasia is common  

Lab diagnosis

  1. Decrease urinary riboflavin exceration < 30 μgm/24 hr.
  2. Decrease level of erythrocyte glutothionine reductase Q  

Niacin [Vita B3)

  1. Coenzyme NAD, NADP takes part in Krebs’ cycle, glycol sis and electron transport.
  2. Cssential for functioning of skin, intestinal tract and nervous system.
  3. In pharmacological doses it control blood cholesterol and lipids
    1 mg of niacin is formed from 60 mg of tryptophane Q

Clinical Deficiency State (Pellagra)

  1. Occur mainly where maize a poor source of tryptophan is a basic food stuff.
  2. Pellagra is also a rare manifestation of (I) carcinoid syndrome in which tryptophan is catabolized by minor pathway (2) Hartnup disease - in which tryptophan is poorly absorbed  



Early symptoms are anorexia, weakness, burring sensation numbness. After a long period of niacin deficiency classic triad of dermatitis, diarrhea and dementia develop. 

  1. The most characteristic manifestations are the cutaneous ones. They first appear as asymmetric erythema of exposed surface.
    On the had → pellagrous glove
    On the foot → pellagrous boot
    Around the neck → Casal necklace Q
  2. Diarrhea when present result from wide spread inflammation of mucous surface. Other mucosal abnormalities include achlorhydria, glossitis, stomatitis, vaginitis.
  3. Nervous system involvement include - depression, disorientation delirium and insomnia.

Mental changes in pellagra may be due to diminished conversion of tryptophan to serotonin


Diagnosis → rapid clinical response to niacin is a important confirming test.


Px – Niotinamide initial Im/Iv then oral


Large doses of niacin may causes cholestatic jaundice or hepatotoxicity.

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