24 Questions
What is the characteristic abnormality of erythroblasts in the bone marrow in megaloblastic anemias?
Maturation of the nucleus is delayed relative to that of the cytoplasm
What is the underlying defect that accounts for the asynchronous maturation of the nucleus in megaloblastic anemias?
Defective DNA synthesis
What is the source of vitamin B12 in nature?
Microorganisms
How do animals acquire vitamin B12?
By eating food of animal origin
What is the structure of vitamin B12?
A cobalt atom at the center of a corrin ring
What is the definition of macrocytic anemia?
Red cells are abnormally large
What is the primary function of vitamin B12 in the body?
To convert methyl THF to THF
What is a common characteristic of the anaemia seen in pernicious anaemia?
Macrocytic anaemia
What is the autoimmune target in pernicious anaemia?
Gastric parietal cells
What is a diagnostic marker for pernicious anaemia?
Intrinsic factor antibody
What is a potential initiating factor for pernicious anaemia?
Helicobacter pylori infection
What is a characteristic of the stomach in pernicious anaemia?
Atrophy of the gastric mucosa
Which of the following food sources does not contain vitamin B12?
Fruits
What is the role of vitamin B12 in DNA synthesis?
Indirectly involved in DNA synthesis
What is the consequence of folate deficiency on DNA synthesis?
Inhibition of thymidylate synthesis
What is the substrate for folate polyglutamate synthesis?
THF
What is the function of 5,10-methylene THF polyglutamate in DNA synthesis?
Synthesis of thymidine monophosphate
What is the term for both natural folates in food and folic acid, the synthetic form used in supplements and fortified food?
Folate
What is the effect of iron deficiency on MCV in megaloblastic anemia?
MCV may be normal
What is characteristic of neutrophils in megaloblastic anemia?
They have hypersegmented nuclei (with six or more lobes)
What is the typical appearance of erythroblasts in the bone marrow of megaloblastic anemia?
They are large with open, fine, lacy chromatin
What is the expected response to correct vitamin therapy in megaloblastic anemia?
The patient's hemoglobin level increases by 20-30 g/L per fortnight
What is the expected timeframe for normalization of white cell and platelet counts after correct vitamin therapy?
7-10 days
What is the characteristic feature of metamyelocytes in megaloblastic anemia?
They are giant and abnormally shaped
Test your knowledge on megaloblastic anemias, including vitamin B12 and folate deficiencies, clinical features, diagnosis, and other macrocytic anemias. Learn about the characteristics and treatment of these blood disorders.
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