Megaloblastic anemia

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Summary of Megaloblastic anemia

Megaloblastic anemia results from inhibition of DNA synthesis during red blood cell production. When DNA synthesis is impaired, the cell cycle cannot progress through the cell cycle properly, leading to cell growth without division, which presents as macrocytosis. Megaloblastic anemia has a rather slow onset, especially when compared to that of other anemias. The defect in red blood cell DNA synthesis is most often due to a deficiency of vitamin B12 and/or folic acid.

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Megaloblastic anemia

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NOTES NOTES MACROCYTIC ANEMIA GENERALLY, WHAT IS IT? PATHOLOGY & CAUSES ▪ Bone marrow produces larger than normal erythrocytes AKA red blood cells (RBCs) CAUSES ▪ Multifactorial: nutritional deﬁcits, genetics, substance exposure (e.g. certain drugs, alcohol) SIGNS & SYMPTOMS ▪ Fatigue, dyspnea, weight loss, pallor, impaired concentration/memory, diarrhea, onychoschizia (brittle nails) DIAGNOSIS LAB RESULTS ▪ ▪ ▪ ▪ ▪ Complete blood count Peripheral blood smear analysis Blood chemistry Iron studies Genetic testing TREATMENT ▪ Address underlying causes MEGALOBLASTIC ANEMIA osms.it/megaloblastic-anemia PATHOLOGY & CAUSES ▪ Macrocytic, normochromic anemia characterized by formation of large RBCs CAUSES Cobalamin and/or folate deﬁciency ▪ Impaired DNA synthesis during erythropoiesis → uncoordinated maturation of cytoplasm and nuclei in erythroblasts (nuclear-cytoplasmic asynchrony) → abnormally large RBCs (macrocytosis) + defective cells with fragile membranes → RBCs die prematurely → anemia B12 deﬁciency ▪ Insufﬁcient diet (e.g. vegan diet without B12 supplements, alcoholism, systemic/mental illness, food insecurity) ▪ Malabsorption ▫ Lack of intrinsic factor → pernicious anemia ▫ Surgical: gastrectomy, bariatric surgery → lack of absorptive surface → pernicious anemia ▫ Pancreatic insufﬁciency → impaired binding of B12 to intrinsic factor → pernicious anemia ▫ Medications that interfere with absorption: e.g. biguanides, H2 receptor blockers, proton-pump inhibitors, neomycin OSMOSIS.ORG 409

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Megaloblastic anemia

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A 33-year-old woman comes to the office because of fatigue and malaise for 2 months. She states that in addition she has new-onset experienced tingling in her feet. Laboratory investigations show the patient has a macrocytic, megaloblastic anemia. The attending physician believes the patient may have a folate deficiency, and chooses to treat her with intravenous folate alone. Which of the following is the most likely consequence of this treatment decision?

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