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Vit a-csbrp


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for Undergraduate medical students (MBBS)

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Vit a-csbrp

  1. 1. Nutritional disorders Dr.CSBR.Prasad, MD.
  2. 2. Vitamins • Definition: Organic micronutrients found in a large variety of foods, which are essential for our health. They act as critical catalytic co-factors / prosthetic groups on enzymes in vital metabolic reactions.
  3. 3. Vitamins Classification: 1-Water soluble vitamins (B-complex and Vit-C) 2-Fat soluble vitamins (Vit-A, D, E, K)
  4. 4. • Fat soluble vitamins: Deficiencies occur mainly due to interference with their absorption ---Pancreatic diseases ---Liver diseases ---Intestinal malabsorption syndromes Vitamins
  5. 5. • Clinical features: • 1-Night blindness • 2-Keratomalasia • 3-Papular desquamation • 4-Frequent respiratory tract infections • 5-Bitot’s spots. Vitamin-A deficiency
  6. 6. Vitamin-A • Chemistry: 1-Retinol (Retinol, Vit-A1, Dehydroretinol, Vit-A2) 2-Availability in diet (2 forms) ----as vitamin-A itself (retinol) ----as provitamin precurssors (carotenoids) (imp: ß-carotene)
  7. 7. • Factors influencing absorption: 1-Dietory fat and proteins 2-Vit-E (prevents its destructions by oxidation) Vitamin-A
  8. 8. E s t e r if ic a t io n w it h p a lm it ic a c id h y d r o ly s is T a r g e t t is s u e e n t e r s b lo o d a n d b o u n d t o R B P F r e e R e t in o l R e t in y l p a lm it a te V i t a m i n - A a s R e t in o l o r C a r o t e n e Vitamin-A
  9. 9. • Requirements (per day): Infants 1500IU Adults 4000-5000IU Pregnancy & lactation 6000-8000IU Vitamin-A
  10. 10. • Serum levels Carotenes 90-220 µg/100ml Vit-A 30-70 µg/100ml • Liver reserves 25-200µg/gm of liver Vitamin-A
  11. 11. Vitamin-A deficiency • Causes: 1-Inadequate diet (very high tissue reserves) 2-Disease of the liver or biliary tract 3-Sprue 4-Severe intestinal disease 5-Generalized protein deficiency (Fall in RBP)
  12. 12. “Vitamin-A deficiency is usually secondary to malabsorption or other situations affecting fat absorption” Irrespctive of the cause in Vit-A deficiency plasma levels fall. Vitamin-A
  13. 13. Vitamin-A deficiency • Disease states: 1-night blindness 2-epithelial metaplasia 3-xerophthalmia 4-keratomalacia 5-follicular keratosis 6-disturbances in bone growth.
  14. 14. lig h t in d a r k S o m e o f t h e r e t in o l is lo s t s p o n t a n e o u s c o m b in a t io n o f t h e a b o v e tw o t o fo r m a g a in R h o d o p s in o p s in + is o m e r o f r e t in a l R h o d o p s in R E T I N A L + O P S IN Vitamin-A deficiency Night blindness Because of the loss vit-A should be made available for the adequate regeneration of Rhodopsin
  15. 15. • Vit-A is necessary for the maintanance of specialized epithelial surfaces (ex: GIT, Respiratory, GUT, Skin) • Vit-A deficiency induces excessive keratinization. Vitamin-A deficiency Epithelial metaplsia
  16. 16. • Epithelium: • 1-other than stratified squamous will under go atrophy and metaplasia (to stra.squ.epi) • 2-stratified squamous epithelium will under go excessive keratinization • 3-non-keratinizing stratified squamous epithelium (ex; cornea, conjunctiva, vagina) become keratinized. Vitamin-A deficiency Epithelial metaplsia
  17. 17. • It’s well established in animals but, strong evidence in humans is lacking. • 1-Deficiency retards normal growth • 2-Excess of Vit-A stimulates bone growth • 3-Epiphyseal bone formation is especially affected • 4-Increased growth rate accompanied by bone resorption leads to increased fragility Vitamin-A deficiency Disturbances in bone growth
  18. 18. • Eyes: 1-Cornea & conjunctiva become keratinized 2-Goblet mucous cells on the surface will disappear 3-Lining of the ducts of lacrimal glands will be replaced by str.squ.epith. 4-Keratin debri form plugs in the ducts 5-Mucosal surfaces become dry and rough (Xerophthalmia) 6-Keratin debri accumulate in conjunctiva producing plaques (BITOT’s spots) 7-Visual acuity is impaired by keratinization & thinning of corneal mucosa resulting in ulceration and softening of cornea (KERATOMALACIA) may lead to perforation Vitamin-A deficiency Pathology
  19. 19. • Respiratory tract: • Atrophy of ciliated columnar epithelium • Squamous metaplasia with keratinization • Impairement of cilialry action & keratin debri accumulation results in recurrent infections. Vitamin-A deficiency Pathology
  20. 20. • Urinary tract (esp. renal pelvis and bladder): • Keratinization of keratin debri formation. • Keratin debri acts as a nidus for stone development • Calculi formation results in infections and hematuria. Vitamin-A deficiency Pathology
  21. 21. • SKIN: • Hyperplasia and hyperkeratinization of epidermis • Plugging of hair shafts and seaceous gland ducts by piled up keratin • Sand paper like skin (Phrynoderma) Vitamin-A deficiency Pathology
  22. 22. “Similar keratin plugs in salivary gland ducts and pancreatic ducts produces significant digestive disturbances”. Vitamin-A deficiency Pathology
  23. 23. • Clinical features: • 1-Night blindness • 2-Keratomalasia • 3-Papular desquamation • 4-Frequent respiratory tract infections • 5-Bitot’s spots. Vitamin-A deficiency Pathology
  24. 24. • Acute • Chronic Vitamin-A TOXICITY
  25. 25. • Acute: Head ache, dizziness, vomiting and diarrhea Raised ICT Occur when >350,000 units are given as in children Vitamin-A TOXICITY
  26. 26. • Chronic: Bone pain, Loss of hair, Skin desquamation, Anorexia, Raised ICT. Occurs if doses >60,000units are given daily Vitamin-A TOXICITY
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