Vitamin B12_Folic acid test.pptx

Testing for Vit B12 and Folic acid deficiency

1. Vitamin B12/Folic acid test

2. Dietary Sources of vitamin b12 B12 is predominantly present in animal products (meat, muscle, fish, eggs, cheese and milk) Therefore, pure vegetarians may suffer from deficiency B12 is synthesized by bacteria in nature. In humans, these bacteria are normal inhabitants of large bowel but B12 cannot be absorbed from this site and thus humans are entirely dependent on dietary sources.

3. Absorption of Vitamin B12

4. Transportation of vitamin B12 Cobalamin is a general term for compounds with biologic vitamin B12 activity. Transport form of Cobalmin: Methylcobalamin) Storage form of cobalamin: adenosylcobalamin. There are three major vitamin B12-binding proteins in plasma namely transcobalamins I, II and III

5. Function of Vitamin B12

6. Folic acid

7. Dietary sources Green leafy vegetables are a rich source of folate. Moderate amounts are present in meat, and milk is a poor source

8. Absorption transport and storage

9. Functions of Folic acid Folates are needed for synthesizing DNA and RNA, as well as the conversion of homocysteine to methionine Synthesis of purines Histidine metabolism (deficiency of folate leads to increase formiminoglutamic acid or FIGLU)

10. Clinical Features of Vitamin B12 Deficiency

11. Laboratory Diagnosis of Megaloblastic Anaemia General blood parameters RBC count and haemoglobin levels are decreased. MCV is increased (>100 fL) Reticulocyte count is normal. Peripheral smear Red cells show the presence of macrocytes and macroovalocytes Neutrophil hypersegmentation Bone marrow Shows megaloblastic hyperplasia

12. Biochemical test Serum vitamin B12 levels <200 pg/mL (normal 200–900 pg/mL) Serum folate levels <6 ng/mL (normal 6–12 ng/mL) There are two methods to measure serum B12—microbiological and radioisotope assay. Radioisotope assay is the preferred method. Serum B12 assay should however be interpreted with caution as it represents the total and not metabolically active B12 Elevated methylmalonic acid (MMA) level indicates depletion of B12 stores Red cells normally contain 20–50 times more folate than serum and red cell folate assay is more reliable than serum folate assay

13. The test is often difficult to do or interpret because of incomplete urine collection or renal insufficiency.

14. Iron Profile

15. Average daily intake of iron in a normal adult: 10–20 mg Eighty percent of functional iron is in haemoglobin: 2–3 g Storage or available tissue iron (ferritin and hemosiderin): 1 g Essential or nonavailable iron (myoglobin and other enzymes of cellular respiration): 0.5 g Iron is transported in the plasma, bound to a glycoprotein called transferrin

16. Iron Heme Iron Non Heme Iron Fe2+ Fe3+

17. Iron Metabolism

18. Fate of Hemoglobin

19. Storage of Iron: Ferritin/ Hemosiderin Free iron is highly toxic For storage, iron is bound to either Ferritin or Hemosiderin Ferritin is a protein-iron complex Found in the liver, spleen, bone marrow, and skeletal muscles Plasma ferritin levels correlate with body iron stores. In iron deficiency, serum ferritin is below 12 μg/L, whereas In iron overload values approaching 5000 μg/L may be seen

20. Food→ Broken down in stomach→ Iron released Heme Iron Fe2+ Non Heme Iron Ferroreductase Fe2+ Fe3+ Ferritin-Fe2+ Stored temporarily Fe2+ Fe3+ Hephaestin Transferrin-Fe3+ TARGET TISSUES Ferritin+Fe3+ Duodenal cell

21. Complete blood count QUANTITATIVE PARAMETERS: Hemoglobin: decreased RBC count: decreased Hematocrit: Decreased QUALITATIVE PARAMETERS MCV: Decreased usually below 75 fL MCH / MCHC: <25pg RDW: >15% WBC COUNT: Normal Platelets: Normal or increased in number

22. 2. Peripheral smear examination Microcytic hypochromic cells Anisocytosis : Variation in size Poikilocytosis or variation in cell shape Elliptocytes, pencil-shaped cells and target cells Increased red cell distribution width (RDW) : Marked in IDA, than thalassemia

23. Peripheral smear- IDA

24. 3. Reticulocyte Count Normal or decreased Due to insufficient iron stores to produce reticulocytes

25. 4. Bone marrow examination Presence of erythroid hyperplasia Cytoplasm shows ragged borders- incomplete hemoglobinization Myelopoiesis and megakaryopoiesis: Normal Prussian blue stain shows decreased iron stores

26. 5. Iron studies S. Ferritin : <15mcg/L indicates depleted iron stores Serum iron : Decreased (Normal: 50-150 mcg/dl) TIBC : increased 360-450 mcg/dl (normal- 300-360 mcg/dl) Transferrin saturation: < 16% Serum transferrin receptor assay : Released by Erythroid precursors in the marrow, increased in IDA Free erythrocyte Protoporphyrin . Protoporphyrin binds iron to form haem in erythroid precursors. In IDA protoporphyrin fails to bind iron and its levels increase.