Name
PERNICIOUS ANEMIA
DESCRIPTION
DETAIL
CAUSES OF MEGALOBLASTIC ANEMIA : A. COBALAMIN DEFICIENCY 1. INADEQUATE INTAKE : VEGETARIANS ( RARE ) 2. MALABSORPTION A. DEFECTIVE RELEASE OF COBALAMIN FROM FOOD - GASTRIC ACHLORHYDRIA - PARTIAL GASTRECTOMY - DRUGS THAT BLOCK ACID SECRETION B. INADEQUATE PRODUCTION OF INTRINSIC FACTOR - PERNICIOUS ANEMIA - TOTAL GASTRECTOMY - CONGENITAL ABSENCE OR FUNCTIONAL ABNORMALITY OF INTRINSIC FACTOR C. DISORDERS OF TERMINAL ILEIUM - TROPICAL SPRUE - NONTROPICAL SPRUE - REGIONAL ENTERITIS - INTESTINAL RESECTION - NEOPLASMS & GRANULOMATOUS DISORDERS ( RARE ) - SELECTIVE COBALAMIN MALABSORPTION ( IMERSLUND SYNDROME) ( RARE ) D. COMPETITION FOR COBALAMIN - FISH TAPEWORM - BACTERIA ( BLIND LOOP SYNDROME ) E. DRUGS - PARA-AMINO SALICYLIC ACID - COLCHICINE - NEOMYCIN 3. OTHERS - NITROUS OXIDE - TRANSCOBALAMIN II DEFICIENCY ( RARE) - CONGENITAL ENZYME DEFECTS ( RARE ) B. FOLIC ACID DEFICIENCY 1. INADEQUATE DIET: ALCOHOLICS 2. INCREASED REQUIREMENTS - PREGNANCY - INFANCY - MALIGNANCY - INCREASED HEMATOPOIESIS - CHR EXFOLIATIVE SKIN DISORDERS - HEMODIALYSIS 3. MALABSORPTION - TROPICAL SPRUE - NONTROPICAL SPRUE - DRUGS : PHENYTOIN, BARBITURATES, ETHANOL 4. IMPAIRED METABOLISM - INHIBITORS OF DIHYDROFOLATE REDUCTASE : METHOTREXATE, PYRIMETHAMINE, TRIAMTERENE, PENTAMIDINE, TRIMETHOPRIM - ALCOHOL - RARE ENZYME DEFICIENCIES : DIHYDROFOLATE REDUCTASE & OTHERS C. OTHER CAUSES 1. DRUGS THAT IMPAIR DNA METABOLISM - PURINE ANTAGONISTS : 6-MERCAPTOPURINE, AZATHIOPRINE ETC. - PYRIMIDINE ANTAGONISTS : 5-FLUOROURACIL, CYTOSINE, ARABINOSIDE ETC - OTHERS : ZIDOVUDINE, PROCARBAZINE, HYDROXYUREA, ACYCLOVIR 2. METABOLIC DISORDERS ( RARE ) - HEREDITARY OROTIC ACIDURIA - LESCH-NYHAN SYNDROME - OTHERS 3. MEGALOBLASTIC ANEMIA OF UNKNOWN ETIOLOGY - REFRACTORY MEGALOBLASTIC ANEMIA - DI GUGLIELMO SYNDROME - CONGENITAL DYSERYTHROPOIETIC ANEMIAOTHER TESTS : * SIGNIFICANT MACROCYTOSIS - MCV > 100 , RETICULOCYTE COUNT- LOW . * PERIPHERAL SMEAR - MARKED ANISOCYTOSIS, POIKILOCYTOSIS, MACROOVALOCYTES, SOME BASOPHILIC STIPPLING & OCCASIONAL NUCLEATED RBC. NUTROPHILS SHOW HYPERSEGMENTATION OF NUCLEUS - CHARACTERISTIC FINDING * SERUM B 12 LEVELS - VERY LOW * BONE MARROW - HYPERCELLULAR, DECREASED MYELOID / ERYTHROID RATIO & ABUNDANT STAINABLE IRON. RBC PRECURSORS ARE ABNORMALLY LARGE WITH MUCH LESS MATURE NUCLEUS. * UNCONJUGATED BILIRUBIN - RAISED * PLASMA LACTIC ACID DEHYDROGENASE ( ISOENZYME 1 ) - RAISED * INCREASED IRON TURNOVER BUT LOW INCORPORATION OF LABELED IRON INTO CIRCULATING RBC. * MEASUREMENT OF RBC FOLATE LEVELS - MORE DIAGNOSTIC * SERUM METHYLMALONIC ACID & HOMOCYSTEINE LEVELS - ELEVATED IN COBALAMIN DEFICIENCY WHILE METHYLMALONIC ACID LEVELS ARE NOT ELEVATED IN FOLATE DEFICIENCY.
TYPENOTES
RELATED DISEASE
Not Available Disease
DISEASE
INVESTIGATION
SERUM BILIRUBIN TOTAL, SERUM BILIRUBIN DIRECT, SERUM L.D.H., SERUM BILIRUBIN INDIRECT, COMPLETE BLOOD COUNT, SERUM FOLATE, SERUM B12, SCHILLING TEST