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Why Iron deficiency causes microcytosis (cells smaller than normal)? This is because the maturing red cells undergo an extra cellular division before the critical haemoglobin concentration required to arrest mitosis is achieved. The cells are also hypochromic…
كريات الدم الحمر تحتاج حد أدنى من الهيموغلوبين حتى تتوقف عن الإنقسام. لما تركيز الهيموغلوبين يكون قليل (بسبب نقص الحديد)، الكريات رح تنقسم لخلايا أصغر لحدما توصل لتركيز الهيموغلوبين المطلوب، لهذا نقص الحديد رح يسبّب microcytosis.
Why B12/Folate deficiency causes macrocytosis (cells larger than normal)?
Both vitamin B12 and folate are essential for DNA synthesis. Defective DNA synthesis (due to a deficiency in either) results in the nucleus maturing at a slower rate than the cytoplasm, in a process called nucleo-cytoplasmic asynchrony. This leads to fewer cell divisions, thereby producing a red cell that is larger than normal (macrocyte).
Both vitamin B12 and folate are essential for DNA synthesis. Defective DNA synthesis (due to a deficiency in either) results in the nucleus maturing at a slower rate than the cytoplasm, in a process called nucleo-cytoplasmic asynchrony. This leads to fewer cell divisions, thereby producing a red cell that is larger than normal (macrocyte).
One of the earliest signs of B12/folate deficiency that even preceeds anemia is hypersegmented neutrophils (neutrophils with 5 or more nuclear lobes).
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Normally, neutrophils have 3-4 (rarely 5) lobes.
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Never treat megaloblastic anemia with folate before making sure the patient doesn't have B12 deficiency
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Never treat megaloblastic anemia with folate before making sure the patient doesn't have B12 deficiency
If a patient has B12 deficiency and you administer folate, this will effectively treat the anemia, but not the neuropathy. And this could mask the neuropathy, delay its diagnosis, and cause more severe (or irreversible) damage to the nervous system.
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Direct vs Indirect Coombs test
الـ Direct يستخدموه عادةً حتى يشوفون إذا الشخص عنده hemolysis لو لا (autoimmune hemolysis مثلًا).
الـ Indirect غرضه هو screening & prevention بالدرجة الأُولى.
الـ Indirect غرضه هو screening & prevention بالدرجة الأُولى.
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Hemolytic anemia
There are some general features of hemolysis and other specific features that help to identify the reason for hemolysis. General features of hemolysis are:
• Decreased hemoglobin level.
• Increased unconjugated bilirubin.
• Increased LDH. This is because RBCs lack mitochondria and must rely on anaerobic respiration to obtain energy.
• Increased reticulocyte count.
• Decreased hemoglobin level.
• Increased unconjugated bilirubin.
• Increased LDH. This is because RBCs lack mitochondria and must rely on anaerobic respiration to obtain energy.
• Increased reticulocyte count.
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Hemolytic anemia
The red cells may give an indication of the likely cause of the hemolysis:
• Spherocytes are small, dark red cells that suggest autoimmune hemolysis or hereditary spherocytosis.
• Sickle cells suggest sickle-cell disease.
• Red cell fragments (schistocytes) indicate microangiopathic haemolysis, such as TTP, DIC, and HUS.
• Bite cells (normal-sized red cells that look as if they have been partially eaten) suggest oxidative hemolysis. They contain Heinz bodies, which attract macrophages to eat them.
• Spherocytes are small, dark red cells that suggest autoimmune hemolysis or hereditary spherocytosis.
• Sickle cells suggest sickle-cell disease.
• Red cell fragments (schistocytes) indicate microangiopathic haemolysis, such as TTP, DIC, and HUS.
• Bite cells (normal-sized red cells that look as if they have been partially eaten) suggest oxidative hemolysis. They contain Heinz bodies, which attract macrophages to eat them.
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Hemolytic anemia
The compensatory erythroid hyperplasia may give rise to folate deficiency, with megaloblastic blood features.