Jul 03, 2023
Bone marrow produces abnormally large red blood cells, which results in the blood disorder known as macrocytic anemia. These abnormal blood cells lack the nutrients that red blood cells require to function normally. There are two types of macrocytic anemia. They expand when your body lacks certain nutrients. Despite the fact that macrocytic anemia is not a dangerous illness, ignoring it might have serious negative effects on your health.
Read this blog further to get a quick overview of this important topic Macrocytic Anemia: Megaloblastic Anemia, Pernicious Anemia, Causes , Diagnosis for pathology and ace your NEET PG exam preparation.
Occurs due to Deficiency of Vitamin B12 and folic acid. Vitamin B12 is Absorbed at terminal ileum. B12 is Absorbed only if B12 is combined with intrinsic factor (IF). Intrinsic factor also called castle's factor is Released by Parietal cells of the stomach. Vegetarian food is deficient in vitamin B12, Food with B12 when ingested,B12 is separated from food by peptic enzymes Enters the stomach then it Binds with haptocorrin - released by Salivary gland. The complex enters the duodenum. Haptocorrin is separated from B12 by Pancreatic enzymes. B12 binds with intrinsic factor (IF) and Moves to the terminal ileum. Terminal ileum has cubilin receptors, B12-IF binds to the receptors and get absorbed. Absorbed B12 is transported by transcobalamin 2. Vitamin B12 is used for Thymidine production which is important for nuclear maturation. In Patients with vitamin B12 deficiency the Nuclear membrane is not matured, Cytoplasm is matured and there is asynchrony between nucleus and cytoplasm ratio.
Vit. B12 Helps in conversion of Methylmalonyl CoA to succinyl CoA and Homocysteine to methionine. Vitamin B12 deficiency doesn't convert the methylmalonyl CoA to succinyl CoA. Methylmalonyl CoA levels increase whereas succinyl CoA levels decrease. Succinyl CoA is important for myelin production. Due to deficiency of myelin production, Leads to Neurological symptoms. Vitamin B12 deficiency doesn't convert homocysteine to methionine. Homocysteine levels increase and methionine levels decrease. Increase in homocysteine levels leads to atherosclerosis.
It is an autoimmune disorder. 3 types of antibodies which causes prenicious anemia are:
Clinical Feature seen only in B12 deficiency and not seen in folic acid deficiency. Neurological manifestations are:
Shows problems associated with:
The RBCs shows the presence of:
Hypersegmentation of neutrophil is observed.
Normal lobes of Neutrophils is 2 to 5 lobes. A neutrophil is said be hypersegmented when 5% of the Neutrophils have 5 lobes. Any 1 neutrophil has more than or equal to 6 lobes. The megaloblastic anemia present with pancytopenia ultimately. In this RBC, WBC and platelets count is low.
Bone marrow hypercellular (hyperplasia)- It is erythroid hyperplasia as RBCs are mostly affected. In normal bone marrow-Myeloid / erythroid ratio is 3:1. In erythroid hyperplasia there will be a reversal of the M / E ratio. More erythrocytes are present. It Shows sieve like chromatin.
Ineffective erythropoiesis causes lysis there is Increases serum bilirubin and LDH.
|Anti IF antibody||Present (Pernicious anemia)|
It is used to find the cause of megaloblastic anemia. It is not for the diagnosis of megaloblastic anemia.
Site of folate absorption - Jejunum. Chromosome controlling the folate metabolism - chromosome 21. Deficiency of folate seen in Alcoholic patients and in Pregnancy, In some cases may cause neural tube defects.
Clinical Features are Same as vitamin B12 deficiency. Neurological symptoms are not seen. Serum folate and RBC folate is less. The FIGLU test is positive. It is Urine test for folic acid deficiency.
Histidine converts to FIGLU (Formimino glutamic acid) and it uses folic acid converts to glutamate In folate deficiency as there is no folate available to convert to glutamate. Therefore, FIGLU is excreted through urine treatment includes vitamin B12 and folic acid supplements.
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