47. Megaloblastic Anemia Flashcards
(16 cards)
What is megaloblastic anemia?
Megaloblastic anemia is a condition resulting from a deficiency in vitamin B12 and/or folate, leading to disrupted DNA synthesis and abnormal development of blood cells.
What are the characteristics of megaloblastic anemia?
It is characterized by an elevated mean corpuscular volume (MCV) above 110 (normal range: 80-100) and is more prevalent in women over 50 years old.
What is the pathogenesis of megaloblastic anemia?
Megaloblastic erythropoiesis occurs due to B12/folate deficiency, leading to large RBCs, hyper-segmented neutrophils, and platelets.
What are the GI causes of vitamin B12 deficiency?
GI causes include gastric atrophy leading to intrinsic factor deficiency, gastrectomy, pancreatic insufficiency, and competitive consumption by bacteria and parasites.
What medications can cause vitamin B12 deficiency?
High doses of vitamin C, metformin, and proton pump inhibitors can lead to vitamin B12 deficiency.
What is the primary etiology of vitamin B12 deficiency?
The main etiology is pernicious anemia, which involves reduced intrinsic factor secretion and autoimmune destruction of gastric mucosal cells causing gastric atrophy.
What are the clinical symptoms of megaloblastic anemia?
Chronic anemia leads to fatigue, exertional dyspnea, and possibly neurological symptoms like peripheral paresthesia.
What can untreated megaloblastic anemia progress to?
If untreated, it can progress to spinal cord degeneration and permanent ataxia.
What are the lab tests for diagnosing megaloblastic anemia?
Lab tests show decreased hemoglobin and RBC count, elevated MCV (above 110), MCH (normal 28-35), oval megalocytosis, severe anisocytosis, poikilocytosis, hyper-segmented neutrophils, elevated serum iron with decreased iron binding capacity, increased LDH, and decreased serum vitamin B12.
What does a myelogram show in megaloblastic anemia?
A myelogram shows hyperplastic bone marrow.
What is the Schilling test used for?
The Schilling test assesses the absorption of vitamin B12 by radioactive vitamin B12.
What is the management for vitamin B12 deficiency?
Administer hydroxo-cobalamin 1mg IM and folic acid orally immediately. Response is seen in 3-5 days with reticulocyte response above 10%. Initial therapy is hydroxo-cobalamin 5 × 1mg IM in the first 2 weeks, then maintenance every 3 months.
What is another main cause of megaloblastic anemia?
Folate deficiency is another main cause of megaloblastic anemia.
How is folate deficiency distinguished in megaloblastic anemia?
It is distinguished by decreased RBC and serum folate levels.
What are the hematological findings in folate deficiency?
Hematological findings are similar to B12 deficiency, showing macrocytic, megaloblastic anemia with reduced folate levels.
How is severe anemia due to folate deficiency treated?
Severe anemia is treated as for B12 deficiency, with prophylactic folate supplements in pregnancy and high-demand states (prematurity).
