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Vitamins

Vitamins. Presented by Dr. Deena Abdel-Hadi Moderator Dr. A. B. Hamam. Vitamin B12 (cyanocobalamin). - Vitamin B12 is derived from cobalamin in food , mainly animal sources , 2ry to production by micro-organisms. - Humans can’t synthesize vitamin B12.

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Vitamins

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  1. Vitamins Presented by Dr. Deena Abdel-Hadi Moderator Dr. A. B. Hamam

  2. Vitamin B12 (cyanocobalamin) -Vitamin B12 is derived from cobalamin in food , mainly animal sources , 2ry to production by micro-organisms. -Humans can’t synthesize vitamin B12. -The cobalamins are released in the acidity of the stomach & combine there with R proteins & IF, traverse the duodenum, where pancreatic proteases break down the R proteins, & are absorbed in the distal ileum via specific receptors for IF cobalamin.

  3. Characteristic: 1. Slightly soluble in water. 2. Stable to heat in neutral solutions. 3. Labile in acid or alkaline solutions. 4. Destroyed by heat. 5. Castle intrinsic factor of the stomach required for absorption.

  4. Biochemical Action: 1. Essential for maturation of RBCs in BM. 2. Metabolism of nervous tissue.

  5. Daily Requirement: Infants: [ 0 - 6/12 ] = 0.3 ug/day. [ 6/12 - 1 yr ] = 0.5 ug/day. Children: [ 1 - 3 yr ] = 0.7 ug/day. [ 4 - 6 yr ] = 1.0 ug/day [ 7 - 10 yr ] = 1.4 ug/day.

  6. Effects of Deficiency: Juvenile pernicious anemia - Rare Autosomal recessive disorder results from an inability to secrete gastric IF or secretion of a functionally abnormal IF. -Other Causes: 1. 2ry to gastrectomy. 2. Celiac disease. 3. Inflammatory lesions of small bowel. 4. Long term drug therapy (neomycin).

  7. Clinical Manifestations: - Prominent symptoms @ 9/12 to 11 yr of age. - Smooth, red & painful tongue. - Neurologic manifestations [ ataxia, parethesias, hypo- reflexia, babiniski responses, clonus & coma]. - Weakness, irritability & anorexia. Lab. Finding: - Serum B12 <100 pg/ml. - High serum LDH level. - absent IF activity in gastric secretion.

  8. - Schilling Test : In which, after body stores of the vitamin are saturated, a tracer dose of radio-active B12 is given by mouth, with or without IF, & urinary excretion measured over the next 24 hr. Defective absorption in the presence of IF, shown by urinary excretion of less than 5% of the dose, occurs when an extensive length of distal ileum is resected or diseased, or when bacterial over-growth occurs within the bowel lumen.

  9. Treatment: - A prompt hematological response follows parenteral administration of vitamin B12 (1 mg),with reticulocytosis in 2-4 days. - The physiological requirement is 1-5 ug/day. - If there is neurological involvement, 1 mg IM daily X 2/52. - Maintenance therapy is 1 mg IM vitamin B12 monthly.

  10. Effect of Excess: Unknown Sources: 1. Muscle & organ meats. 2. Fish. 3. Eggs. 4. Milk . 5. Cheese.

  11. Folate ( Folic Acid) The disease is caused by a deficient intake or absorption of folic acid . Folic acid is absorbed throughout the small intestine ( the specific nature of folate receptors & transport via the intestinal cell is not clear) . Surgical removal or disorders of small intestine may lead to folate deficiency.

  12. Dietary deficiency is usually compounded by rapid growth or infection, which may increase folic acid requirements. The needs are also increased with accelerated tissue turnover, as in hemolytic anemia. Human & cows milks provide adequate amounts of folic acid. Goat’s milk is clearly deficient. Unless supplemented, powdered milk may also be a poor source of folic acid.

  13. Daily Requirement: Infants: [ 0 - 6/12]= 25 ug/day. [ 6/12 - 1 yr]= 35 ug/day. Children: [ 1 – 3 yr ] = 50 ug/day. [ 4 – 6 yr ] = 75 ug/day. [ 7 – 10 yr ] = 100 ug/day.

  14. Effects of Deficiency: Megaloblastic Anemia of Infancy Clinical manifestation: - Megaloblastic anemia has been reported in VLBW, its peak incidence at 4 - 7 month of age. - Irritability, failure to gain weight & chronic diarrhea. - Hemorrhages due to thrombocytopnia occur in advanced cases.

  15. Laboratory Findings: - Macrocytic anemia (MCV more than 100 fl). - Low reticulocyte count. - Nucleated RBCs. - Neutropenia & thrombocytopenia ( long standing deficiency ). - Large neutrophils with hyper segmented nuclei ( more than 5% of neutrophils have 5 or more nuclear segments). - Low serum folic acid less than 3 ng/ml (5 - 20 ng/ml). - Levels of RBCs folate (150 - 600 ng/ml).

  16. Treatment: 1-5 mg/day P.O. or parenterally. 50-100 ug/day for a week (doubt diagnosis). 1 ug/day parenterally (for ? B12 deficiency). Folic acid therapy should be continued for 3 - 4 weeks. Sources: 1. Green vegetables. 2. Fruits. 3. Animal organs (liver & kidney).

  17. Vitamin C (ascorbic acid) Characteristics: 1. Water soluble 2. Easily oxidized, accelerated by: - Heat. - Light. - Alkali oxidative enzymes. - Traces of copper or iron.

  18. Biochemical Action: 1.Integrity & maintenance of intracellular material. 2. Facilitates absorption of iron & conversion of folic acid to folinic acid . 3. Metabolism of tyrosine & phenylalanine 4. Regulation of serum phosphatase in infants.

  19. Daily Requirement: Infants [ 0 - 6/12] = 30 mg/day [6/12 - 1 yr] = 35 mg/day Children [1-3 yr] = 40 mg/day [4 - 6 yr] = 45 mg/day [7 - 10 yr] = 45 mg/day

  20. Effects of Deficiency: 1. Scurvy. 2. Poor wound healing.

  21. Scurvy - Ascorbic acid is essential for the formation of normal collagen. - Breast milk contains about 4 - 7 mg/dl of ascorbic acid & is an adequate source of vitamin C . - Deficiency of vitamin C in the mother’s diet may result in scurvy in their breast-fed infant.

  22. - The need for vitamin C is increased by: 1. Febrile illnesses, particularly infectious & diarrheal diseases. 2. Iron deficiency. 3. Cold exposure 4. Protein depletion. 5. Smoking.

  23. The tendencies to hemorrhage, defective tooth dentin & loosening of the teeth are caused by deficient collagen. Because osteoblasts no longer form their normal intracellular substance (osteoid), endochondral bone formation ceases; the bony trabeculae that have been formed become brittle & fracture easily . In sever scurvy there may be: - Degeneration in skeletal muscles - Bone marrow depression. - Cardiac hypertrophy. - Adrenal atrophy.

  24. Clinical manifestations: - Rare in the newborn infant. - Peak incidence at 6 - 24 month of age. - Presented as vague symptoms of irritability, tachypnea, digestive disturbances& loss of appetite. - There is general tenderness (legs). - Petecheal hemorrhages may occur in the skin & mucous membranes. - Hematuria, melena, orbital & subdural hemorrhages may be found. - Delayed wound healing. - Ground-glass bone X ray appearance.

  25. Treatment: - The administration of 3 - 4 oz of orange juice or tomato juice daily will quickly produce healing, but ascorbic acid is preferable. - The daily therapeutic dose is 100-200 mg or more,P.O. or parentally.

  26. Effects of Excess: oxaluria

  27. Sources: 1. Citrus fruits 2. Tomatoes. 3. Berries. 4. Cantaloupe. 5. Cabbage. 6. Green vegetables. Cooking has destructive effect.

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