Megaloblastic Anemia

1. Megaloblastic Anemia Teoman SOYSAL Prof.MD

2. Megaloblastic Anemia • A subclass of macrocytic anemia (under morphologic classification) Or • A subclass of anemias due to defective DNA synthesis (pathogenetic classification)

3. Megaloblastic Anemia • Main causes of “Megaloblastic Anemia” • Vit.B12 deficiency • Folic acid deficiency • Others

4. Megaloblastic Anemia • 30-50 % of all macrocytic anemias are caused by folic acid and/or Vit.B12 deficiency.

5. Vit B12 • Metabolic active cobalamins in the body are; • Methyl cobalamin and adenosyl cobalamin • Hydroxocobalamin can be reversed to the above cobalamins. • Pharmacy: • Most stable cobalamin: cyanocobalamin

6. Vit B12 • Natural forms • Produced by microorganisms (bacteria/fungi) • Plants do not produce or contain Vit B12 (except contamination) • Colonic bacterial production occurs but their location is distal to the site of absorbtion

7. Vit.B12 • Food sources rich in Vit.B12 • Liver • Kidney • Muscle • Egg • Milk ,Cheese and other diary products • Seafood

8. Plants are not sources of Vit.B12

9. Vit.B12 Daily requirements Age Amount/day 0 - 1 0.3 – 0.5 g, 1 – 10 0.7 – 1.5 g Adults 2g . Pregnancy (2g + ) 2nd Trimestr 0.5g 3rd Trimestr 1g Lactation 2.5 – 3 g

10. Vit.B12 • Average diet contains 5 – 30g Vit. B12 daily • The amount of Vit. B12 in the body is about 2 – 5 mg. • Most of it is in the liver. • The store is sufficient for 3-6 years in case of impaired absorbtion. • The storage form is mainly adenosylcobalamin.

11. B12 in diet R-Binder Parietal cell IF R - B12 stomach Duodenum and jejunum Pancreas enzymes R- B12 Enterohepatic circulation B12 B12 IF B12 TC II B12 Ileum cells IF - B12 İleum

12. Vit.B12 • Circulates with TCII and TCI in plasma. • Generally in the form of methylcobalamin. • Although most of the B12 is bound to TCI , • TCII is the functional carrier, rapidly cleared from plasma. • TCII deficiency is a cause of megaloblastic anemia.

13. Vit .B12 Plazma level of Vit. B12 • 200 - 900 ng/ L

14. Functions of Vit.B12 1) Methylmalonyl co - A mutase Methylmalonyl co - A succinyl co - A 5-deoxyadenosyl B12

16. Functions of Vit.B12 2- Methyl FH4FH4 HomocysteinMethioninSAM B12 Methionin synthase

18. Folic Acid Pteroyl glutamic acid and similar compounds are termed as folic acid . Polyglutamate is the natural form. Dihydro or tetrahydro folate are metabolic active forms.

19. Folic acid Sources : • Produced by plants and some microorganisms • Folate rich foods; • vegetables (Green leaf), • Liver and kidney (parenchymal organs) • Molds.

20. Folic acid Daily requirements Age • 0 - 10 3.6g /kg • > 10 3g /kg • Pregnants 500 g • Lactation +100 g • Diet contains 100 - 500 g folate/day.

21. Folate absorbtion • Mainly jejunum. • In the form of monoglutamate . • Methyltetrahydrofolate monoglutamate is the form it is found in serum .

22. Folate levels: Normal ranges • Serum: 6 – 21 g/L (RBC volume) • Red cell: 160 – 640 g/L (RBC volume) Folate deficiency • Serum folate : <4g /L • Red cell folate: <140g /L

23. Folate stores • Total body folate: 5 – 20 mg • Storage place : Liver • Storage form: Methyl-FH4 polyglutamate

24. Functions of folic acid: Transfer of methyl or formyl groups to other compounds. eg-During the production of thymidylate for the synthesis of DNA (methylation of deoxyuridylate) Source of the 1-carbon moieties; 1-serine Serine + THF glycine + N-methylene THF 2-Formiminoglutamic acid Formiminoglutamate+FH4 glutamate+N-formimino THF

25. Thymidylate synthase Deoxyuridilate DNA-thymine Thymidilate Methylene THFA Dihydrofolate THFA Dihydrofolate reductase serine Methyonine glycine B12 Homocystein Methyl THFA

26. Megaloblastic Hematopoiesis • Anemia +/- leukopenia +/- thrombocytopenia. Causes of cytopenias : 1-DNA synthesis is deranged 2-Ineffective hematopoiesis 3-Shortened RBC survival

27. Causes of Megaloblastic Anemia • Vit. B12 deficiency • Folate deficiency • Other causes

28. Causes of VitB12 deficiency I-Decreased intake ( complete vegetarianism) II-Impaired absorbtion • Gastric causes ( Pernicious anemia, gastrectomy , caustic injury, Zollinger-Ellison ) • Intestinal causes ( Ileal resection or disease,eg:sprue,blind loop syndr,Diph.Latum, ) • Pancreatic disease-(insufficiency) • Familial selective Vit B12 absorbtion defect (Imerslund –Grasbeck) • Drugs ( PAS, colchicin, neomycine, omeprazol,potasyum chloride,ethanol ) III-Other causes

29. Causes of folate deficiency • Decreased intake • Increased demands • Drug related folate insufficiency

30. Causes of Folate deficiency A) Decreased intake 1-Dietary causes Senility, Alcoholism Hyperalimentation Hemodialysis Prematurity Synthetic diet feeding Goat’s milk feeding 2- Malabsorbtion Nontropical sprue Tropical sprue Intestinal resection Other intestinal diseases

31. Causes of Folate Deficiency B) Increased demands Pregnancy Chronic hemolytic diseases Myeloproliferative diseases Dermatitis(expholiat.) Hyperthyroidism C) Drugs Oral contraseptive drugs Some anticonvulsant drugs Triamterene Cholestyramine

32. Other causes of megaloblastic anemia (1) I- Combined deficiency of Folate and Vit B12 : • Tropical sprue • Gluten enteropathy II- Acute megaloblastic anemia: • Nitrous oxide anesthesia • Dialysis • Severe disease + antifolate drug (eg:trimethoprim) • Total parenteral feeding

33. Other causes of megaloblastic anemia (2) III- Megaloblastic anemia due to drugs • Dihydrofolate reductase inhibitors (eg:MTX,trimethoprim) • Purine antagonists (eg: 6 MP, azathioprin) • Pyrimidine antagonists ( eg: ARA-C) • Alkylators (eg: cyclophosphamide ) • Zidovudine

34. Other causes of megaloblastic anemia (3) IV- Inherited metabolic diseases: • Orotic asiduria • Lesch-Nyhan syndrome • Thiamine responsive megaloblastic anemia • Transcobalamin II deficiency • Homocystinuria , methyl malonic asiduria • Deficiency of enzymes of folate metabolism Methyl tetrahydrofolate transferase Formimino transferase Dihydrofolate reductase V- Other: • Erythroleukemia (?)-not an anemia- alike only morphologically

35. Clinical features of megaloblastic anemia Folic acid deficiency AnemiaAtrophic glossitisNeurologic changes Vit B12 Deficiency

36. Tissues or organs other than bone marrow are also affected • Skin,GIS, female genital system mucosal epithelium • Congenital abn.(neural tube defects) • Neurologic changes(Vit.B12 deficiency) • Peripheral neuropathy • Subacute combined degeneration of spinal cord • Cerebral -Mental changes • Hyperhomocysteinemia

37. Clinical findings(1) • Anemia: Symptoms of anemia + palor+slight icterus • Glossitis : Sore tongue, poor taste sensation, pain Papill. atrophy-beefy tongue

39. Clinical findings(2) • Neurologic changes-Vit B12 deficiency (may occur without anemia) Paresthesias Loss of position sense, ataxia Decreased deep tendon reflexes Muscle weakness Loss of vibration sense ( post column ) Spasticity, reflex changes, Babinsky (lateral column ) Romberg Mental changes:Memory loss, confusion, dementia, hallutination etc

40. Clinical findings(3) • Other signs: Vitiligo Hyperpigmentation Premature graying of hair Weight loss Fever Diarhea Constipation Meteorismus Splenomegaly

41. Peripheral bloodCBC:Anemia  Leukopenia  Thrombocytopenia

42. RBC Indexes: • MCV • MCH • RDW

43. Peripheral smear(1) : RBC’s • Macroovalocytosis , • Anisocytosis, poikilocytosis , • Bazophilicstippling , • Howell-JollybodiesandCabot ring, • Nucleatedredcells

44. Peripheral smear(2) : Neutrophyls • Neutrophyl hypersegmentation (an early sign of megaloblastic hematopoiesis)

46. Bone marrow findings in megaloblastic anemia

47. Bone marrow Hypercellular with erythroid hyperplasia. Erythroid series • Giant erythroblasts called megaloblasts • Increased numbers of early erythroblasts • Nuclear cytoplasmic asynchronism • Increased mytosis

48. Bone marrow • Giant metamyelocytes and bands • Giant megakaryocytes • Increased bone marrow iron stores

49. Biochemical findings • LDH ( LDH -1> LDH - 2) • Bilirubin(indirect) • Ferritin and serum iron • Haptoglobin