BCR TBL 9 - Disorders of Red Blood Cells, Platelets and Clotting
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209 Terms
What is the average lifespan of a red blood cell?
120 days
What phase begins red cell production's dependence on iron?
Erythroblast phase
What is a reticulocyte?
Immature red blood cell
Where is iron absorbed in the gastrointestinal tract?
Duodenum
What form must dietary iron be converted to for absorption?
Ferrous (Fe2+)
Which transporter moves non-heme iron across the enterocyte membrane?
DMT1
Which transporter is responsible for heme iron absorption?
HCP1
What reduces ferric iron (Fe3+) to ferrous iron (Fe2+)?
Duodenal cytochrome B
Which protein exports iron from enterocytes to plasma?
Ferroportin
Which protein oxidizes ferrous iron to ferric iron for transport?
Hephaestin
What protein binds iron in the blood to prevent toxicity?
Transferrin
What stimulates hepcidin production?
Inflammation (e.g., IL-6)
What is the function of hepcidin?
Regulates iron by inactivating ferroportin
What happens to hepcidin levels during iron deficiency?
They decrease
What is the primary site of iron storage?
Liver
What type of cell stores iron in the liver?
Kupffer cells
What is haemosiderin?
An iron storage complex seen in iron overload
Which cells phagocytose senescent red cells?
Macrophages (mainly in spleen)
What is the fate of iron after red cell destruction?
It is recycled and reused
What is the role of iron-responsive elements (IREs)?
Regulate iron-related protein translation
What happens to IRE-IRP interaction when iron is low?
It increases, enhancing DMT1 production
What is a clinical sign of chronic iron deficiency in the nails?
Brittle or spoon-shaped nails
What oral symptom is seen in iron deficiency?
Stomatitis or sore tongue
What condition may first present as iron deficiency anaemia in older adults?
Gastrointestinal cancer
What IV iron side effect requires caution?
Anaphylaxis
When is IV iron preferred over oral iron?
Urgent cases or intolerance to oral iron
Why is slow-release oral iron not first-line?
Poor absorption compared to standard formulations
How soon should iron studies be rechecked after starting therapy?
4 to 12 weeks
Which vitamin is essential for converting homocysteine to methionine?
Vitamin B12
Which food sources are richest in folate?
Green vegetables and liver
Why do patients with folate deficiency develop macrocytic anaemia?
Impaired DNA synthesis
Why is intrinsic factor essential?
Allows B12 absorption in terminal ileum
What binds B12 in the stomach before intrinsic factor?
Haptocorrin
Where is intrinsic factor produced?
Parietal cells of the stomach
Which autoimmune condition affects B12 absorption?
Pernicious anaemia
Which test detects pernicious anaemia?
Anti-intrinsic factor antibody
Why can folate therapy worsen undiagnosed B12 deficiency?
It may mask anaemia while neuropathy progresses
Which deficiency is associated with glossitis and taste changes?
Folate deficiency
What is the function of B12 in red cell production?
DNA synthesis
Which deficiency can cause combined anaemia, thrombocytopenia, and leukopenia?
Vitamin B12 or folate deficiency
What are the features of a reticulocytopenic anaemia?
Low reticulocyte count, indicating decreased marrow response
What does pancytopenia mean?
Deficiency of red cells, white cells, and platelets
Which anaemia is defined by bone marrow failure without infiltration?
Aplastic anaemia
What does a hypocellular bone marrow indicate?
Decreased production capacity
What infection is linked to pure red cell aplasia in inherited bone marrow disorders?
Parvovirus B19
Which condition is a potential trigger for red cell aplasia?
Thymoma
Which condition is a potential autoimmune cause of anaemia?
Systemic lupus erythematosus (SLE)
What is the primary feature of pure red cell aplasia?
Selective absence of erythroid precursors
What is the role of thrombopoietin receptor agonists?
Stimulate platelet production
What is the mode of action of anti-thymocyte globulin (ATG)?
Immunosuppression for aplastic anaemia
Which condition involves both haemolysis and pancytopenia?
Paroxysmal nocturnal haemoglobinuria (PNH)
What is the main diagnostic test for PNH?
Flow cytometry for CD55 and CD59
Which structure is deficient in PNH red cells?
GPI anchor
What is the complement inhibitor used to treat PNH?
Eculizumab
What is a potential complication of untreated PNH?
Thrombosis
What triggers complement activation in PNH?
Absence of protective surface proteins
What haemolytic condition is commonly seen post-viral infection in children?
Paroxysmal cold haemoglobinuria
What is the pathogenesis of biphasic antibodies in cold haemoglobinuria?
Bind at cold temp, fix complement at warm temp
What symptom is classic in cold haemagglutinin disease?
Raynaud-like acrocyanosis
What antibody type is involved in CHAD?
Usually IgM
What is the most effective long-term treatment for CHAD?
Anti-CD20 immunotherapy (e.g., rituximab)
What is the most common presentation of warm AIHA?
Acute anaemia with jaundice
Which complement component is involved in intravascular haemolysis?
C3/C5 leading to MAC formation
What is the role of haptoglobin in intravascular haemolysis?
Binds free haemoglobin
Which protein binds heme in intravascular haemolysis?
Hemopexin
What is methaemalbumin?
Complex of heme and albumin
What is seen in the urine during chronic haemolysis?
Haemosiderin
What causes agglutination in cold AIHA?
IgM-mediated cross-linking of RBCs
What test must be performed at 37°C for CHAD diagnosis?
Cold haemagglutinin screen
Which drug class is most effective in warm AIHA?
High-dose corticosteroids
Which blood film feature supports warm AIHA?
Spherocytes
What is the role of folic acid in haemolytic anaemia?
Supports increased RBC production
What is the main side effect of splenectomy in haemolytic anaemia?
Increased infection risk
What shape are RBCs in elliptocytosis?
Elliptical
What inheritance pattern is elliptocytosis?
Autosomal dominant or recessive
What triggers haemolytic crisis in G6PD deficiency?
Infections, fava beans, drugs
What population is most affected by G6PD deficiency?
Males (X-linked recessive)
What does pyruvate kinase deficiency cause?
Chronic haemolysis due to reduced ATP
What is a common presentation of spherocytosis in neonates?
Jaundice at birth
Which stone type is common in chronic haemolysis?
Pigmented gallstones
What is the result of haemoglobin precipitation in thalassaemia?
Red cell damage and ineffective erythropoiesis
Which haemoglobinopathy is lethal in utero without intervention?
Alpha thalassaemia major (Hb Bart’s)
What happens to RBC count in thalassaemia trait?
Typically increased
Which blood smear feature is classic for thalassaemia?
Target cells
What is the relationship between iron and MCV in thalassaemia?
Low MCV, even with normal/high iron
Why must Hb electrophoresis be delayed post-transfusion?
Donor blood may mask haemoglobinopathy
What is the threshold for initiating prophylactic transfusions in thalassaemia major?
Moderate to severe anaemia with symptoms
What is the rationale for iron chelation in thalassaemia?
Prevent organ damage from iron overload
What is the current curative option for haemoglobinopathies?
Bone marrow transplant
What technology is being trialed as a cure for sickle cell disease?
Gene therapy (e.g., CRISPR-modified stem cells)
What kind of therapy is crizanlizumab?
P-selectin monoclonal antibody
What symptom distinguishes sickle cell crisis from other anaemias?
Sudden, severe pain episodes
What is the main complication in sickle cell acute chest syndrome?
Pulmonary infiltrates leading to hypoxia
What causes stroke in sickle cell disease?
Cerebral vessel occlusion by sickled cells
What is the function of NETs in VOC?
Amplify inflammation and thrombosis
What is the most important chronic management for sickle cell patients?
Hydroxyurea and vaccination
What is the role of penicillin prophylaxis in sickle cell?
Prevents infections due to splenic dysfunction
What does haemoglobin C cause when combined with HbS?
Sickle cell-HbC disease
Which syndrome involves vascular malformations and mucosal bleeding?
Hereditary haemorrhagic telangiectasia (Rendu-Osler-Weber)
What condition presents with purpura, joint pain, and renal involvement?
Henoch-Schönlein purpura (IgA vasculitis)