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Haematology > Red Cells > Flashcards

Red Cells Flashcards

1
Q

How are red cells produced?

A
  • in bone marrow
  • haemocytoblast -> proerythroblast -> early erythroblast -> late erythroblast -> normoblast -> reticulocyte -> erythrocyte
  • requires substances
  • metals: iron, copper, cobalt, maganese
  • vitamins: B12, folic acid, thiamine, B6, C, E
  • amino acids
  • hormones: erythropoietin, GM-CSF, androgens, thyroxine
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2
Q

How are red cells broken down?

A
  • broken down in reticuloendothelial system
  • macrophages in spleen, etc
  • 120 day lifespan
  • globulin
  • amino acids (reutilised)
  • haem
  • iron (recycled into haemoglobin)
  • haem -> biliverdin -> bilirubin
  • bulirubin (bound to albumin in plasma)
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3
Q

What are the main genetic defects of red cells which cause congenital anaemia?

A
  • membrane
  • metabolic pathways (enzymes)
  • haemoglobin
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4
Q

How is the normal red cell membrane maintained?

A
  • skeletal proteins maintain red cell shape + deformability
  • skeletal proetin defects can inc. cell destruction
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5
Q

What is Hereditary Spherocytosis?

A
  • defects in red cell membrane structural proteins (autosomal dominant)
  • ankyrin, alpha spectrin, beta spectrin, band 3, protein 2.4
  • red cells are spherical
  • removed from circulation by reticuloendothelial system
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6
Q

What are the presentations and treatment for Hereditary Spherocytosis?

A
  • anaemia
  • jaundice (neonatal)
  • splenomegaly
  • pigment gallstones
  • folic acid
  • transfusion
  • splenectomy (if anaemia very severe)
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7
Q

What are other red cell membrane disorders?

A
  • hereditary elliptocytosis
  • hereditary pyropoikilocytosis
  • south east asian ovalocytosis
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8
Q

What are the metabolic pathways red cells are involved in?

A
  • glycolysis
  • pentose phosphate shunt
  • glucose 6 phosphate dehydrogenase (G6PD)
  • protects red cellsfrom oxidative damage
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9
Q

What is G6PD deficiency?

A
  • causes enzymopathy
  • makes red cells vulnerable to oxidative damage
  • condition gives protection against malaria
  • X linked
  • affects males, female carriers
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10
Q

What are the presentations of G6PD deficiency?

A
  • anaemia
  • jaundice (neonatal)
  • splenomegaly
  • pigment gallstones
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11
Q

What can trigger haemolysis in G6PD deficiency?

A
  • infection
  • broad beans
  • drugs
  • antimalarials
  • sulphonamides + sulphones
  • antibacterial
  • analgesics (aspirin)
  • antihelminthics
  • others
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12
Q

What are other red cell enzyme deficiencies?

A
  • pyruvate kinase deficiency
  • dec. ATP
  • inc. 2,3-DPG
  • cells rigid
  • anaemia
  • jaundice
  • gallstones
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13
Q

What is the structure of haemoglobin?

A
  • 2 alpha chains
  • 2 beta chains
  • haem
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14
Q

What is the function of haemoglobin?

A
  • gas exchange
  • O2 to tissues
  • CO2 to lungs
  • compensatory mechanisms for changes in PO2
  • acidosis
  • hyperthermia
  • hypercapnia
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15
Q

What is sickle cell disease?

A
  • sickle haemoglobin (HbS)
  • 2 alpha chains
  • 2 beta (sickle) chains
  • red cell injury, cation loss, dehydration
  • haemolysis
  • enothelial activation, promotion of inflammation, coagulation activation, dysregulation of vasomotor tone by vasodilatior mediators (NO)
  • vaso-occlusion
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16
Q

What are presentations of sickle cells disease?

A
  • painful vaso-occlusion crises
  • bone
  • chest crisis
  • stroke
  • inc. infection risk
  • hyposplenism
  • chronic haemolytic anaemia
  • gallstones
  • aplastic crisis
  • sequestration crises
  • spleen, liver
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17
Q

What is the treatment for a sickle cell painful crisis?

A
  • opiates
  • hydration
  • oxygen
  • consider antibiotics
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18
Q

What is the management for sickle cell disease?

A
  • life long prophylaxis
  • vaccination
  • penicillin prophylaxis
  • folic acid
  • blood transfusion (episodic or chronic)
  • alloimmunisation
  • iron overload
  • disease modifying drugs
  • hydroxycarbmide
  • bone marrow transplant
  • gene therapy
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19
Q

What is thalassaemias?

A
  • reduced/absent globin chain production
  • mutations or deletions in alpha genes (alpha thalassaemias) or beta genes (beta thalassaemias)
  • chain imbalance
  • chronic haemolysis
  • chronic anaemia
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20
Q

What are the different types of thalassaemias?

A
  • homozygous alpha zero thalassaemia
  • no alpha chains
  • hydrops fetalis- incompatible with life
  • beta thalassaemia major
  • no beta chain
  • transfusion dependant anaemia
  • non-transfusion dependant thalassaemia “intermedia”
  • thalassaemia minor
  • common
  • trait or carrier state
  • hypochromic microcytic red cell indices
21
Q

What are the presentation of beta thalassaemia major?

A
  • severe anaemia
  • at 3-6 months age
  • expansion of ineffective bone marrrow
  • bone deformities
  • splenomegaly
  • growth retardation
  • life expectantcy < 10 yrs, if untreated/irregular transfusion
22
Q

What is the treatment for beta thalassaemia major?

A
  • chronic transfusion support (4-6 weekly)
  • normal growth + development
  • iron overload
  • death in 2nd/3rd decade if iron overload untreated (heart/liver/endocrine failure)
  • iron chelation therapy
  • s/c desferrioxamine infusions
  • oral deferasirox
  • good adherance to chelation
  • regular monitoring (ferritin + MRI scans)
  • bone marrow transplantation (curative)
23
Q

What are other haem synthesis defects?

A
  • sideroblastic anaemia
  • defects in haem synthesis at mitochondrial steps
  • ALA synthase mutations
  • hereditary
  • aquired- myelodysplasia
  • porphyrias
  • defects in cytoplasmic steps
24
Q

What are factors that effect normal range of Hb?

A
  • age
  • sex
  • ethnic origin
  • time of day
  • time to analysis of sample
25
Q

What are reference ranges of haemoglobin?

A
  • male 12-70 yrs (140-180)
  • male > 70 yrs (116-156)
  • female 12-70 yrs (120-160)
  • female < 70 yrs (108-143)
26
Q

What are features of anaemia?

A

Due to dec. oxygen delivery to tissues:

  • tiredness
  • pallor
  • breathlessness
  • ankle swelling
  • dizziness
  • chest pain

Related to underlying cause:

  • evidence of bleeding (menorrhagia, dyspepsia, PR bleeding)
  • symptoms of malabsorbtion (diarrhoea, weight loss)
  • jaundice
  • splenomegaly
  • lymphadenopathy
27
Q

What are red cell indices?

A
  • MCH- mean cell haemoglobin
  • MCV- mean cell volume
  • can give morphological description- may be related to cause
  • hypochromic microcytic
  • normochromic normocytic
  • macrocytic
28
Q

What tests are indicated from each morphological description?

A
  • hypochromic microcytic
  • serum ferritin
  • normochromic normocytic
  • reticulocyte count
  • macrocytic
  • B12/folate bone marrow
29
Q

What can serum ferritin indicate?

A
  • low- iron deficiency
  • high- thalassaemia secondary anaemia (sideroblastic anaemia)
30
Q

What happens to absorbed iron in the body?

A
  • bound to mucosal ferritin + sloughed off

OR

  • transported across basement mebrane by ferroportin
  • then bound to transferrin in plasma
  • stored as ferritin- mainly in liver
31
Q

What is the role of hepcidin in iron metabolism?

A
  • hepcidin synthesised in liver, in reponse to inc. iron + inflammation
  • blocks ferroportin to dec. intestinal iron absorption + mobilisation from reticuloendothelial cells
32
Q

What are features of iron defciency anaemia?

A
  • dyspepsia, GI bleeding
  • other bleeding, e.g. menorrhagia
  • diet
  • inc. requirement, e.g. pregnancy
  • atrophic tongue
  • angular cheilitis
  • koilonychia

*description, NOT diagnosis, must determine cause

33
Q

What are causes of iron deficiency anaemia?

A
  • GI blood loss
  • menorrhagia
  • malabsorption
  • gastrectomy
  • coeliac disease
  • gastric ulcer
  • colon carcinoma
  • gastritis
34
Q

What is the management for iron deficiency anaemia?

A
  • correct deficiency
  • oral iron
  • IV iron
  • blood transfusion
  • correct cause
  • diet
  • ulcer therapy
  • gynae interventions
  • surgery
35
Q

What can reticulocyte count indicate?

A
  • inc- acute blood loss haemolysis
  • normal/dec- secondary anaemia (hypoplasia, marrow infiltration)
36
Q

What is secondary anaemia?

A
  • anaemia of chronic disease
  • defective iron utilisation
  • inc. hepcidin in inflammation
  • ferritin often elevated
  • identifiable underlying disease
  • infection, inflammation, malignancy
37
Q

What is haemolytic anaemia?

A
  • accelerated red cell destruction (dec. Hb)
  • compensation by bone marrow (inc. retics)
  • level of Hb- balance between red cell prodcution + destruction
  • haemolysis can be extra or intravascular
38
Q

What are causes of haemolytic anaemia?

A
  • congenital
  • hereditary spherocytosis
  • enzyme deficiency
  • haemoglobinopathy
  • aquired
  • autoimmune haemolytic anaemia (extravascular)
  • mechanical (intravascular)
  • severe infection/DIC (intravascular)
  • PET/HUS/TTP (intravascular)
39
Q

What is the direct antiglobulin test?

A
  • detects antibody or compliment on red cell membrane
  • reagent contains either; anti-human IgG or anticomplement
  • reagent bind to Ab/complement on red cell surface, causes agglutination in vitro
  • implies immune basis for haemolysis
  • if +ve- immune mediated haemolytic anaemia
  • if -ve- non-immune mediated haemolytic anaemia
40
Q

What are the different types of immune haemolysis and their causes?

A
  • warm auto-antibody
  • auto-immune
  • drugs
  • CLL
  • cold auto-antibody
  • CHAD
  • infections
  • lymphoma
  • alloantibody
  • transfusion reaction
41
Q

What tests show if a patient is haemolysing?

A
  • FBC, reticulocyte count, blood film
  • serum bilirubin, LDH
  • serum haptoglobin
42
Q

What tests show the mechanism of haemolysis?

A
  • history + examination
  • blood film
  • direct antiglobulin test (Coomb’s test)
  • urine for haemosiderin/urobilinogen
43
Q

What is the management for haemolytic anaemia?

A
  • support marrow function
  • folic acid
  • correct cause
  • immunosuppression if autoimmune (steroids, treat trigger)
  • remove site of red cell destruction (splenectomy)
  • treat spesis, leaky prosthetic valve, malignancy, etc (if intravascular)
  • consider transfusion
44
Q

What can B12/folate assay indicate?

A
  • megaloblastic
  • B12 deficiency
  • folate deficiency
  • non-megaloblastic
  • myelodysplasia
  • marrow infiltration
  • drugs
45
Q

What are the symptoms and causes of B12 + folate deficiency?

A
  • anaemia
  • neurological symptoms
  • ‘lemon yellow’ tinge

B12 causes:

  • pernicious anaemia
  • gastric/ileal disease

Folate causes:

  • dietary
  • inc. requirements
  • GI pathology
46
Q

What is pernicious anaemia?

A
  • commenest cause of B12 deficiency
  • autoimmune disease
  • antibodies against; intrinsic factor, gastric parietal cells
  • malabsorbtion of dietary B12
  • symptoms take 1-2 yrs to develop
  • Schilling test
47
Q

What is the treatment for megaloblastic anaemia?

A
  • replace vitamin
  • B12 IM injection
  • loading does, then 3 monthly maintenance
  • oral folate replacement
  • ensure B12 normal if neuropathic symptoms
48
Q

What are other causes of macrocytosis?

A
  • alcohol
  • drugs
  • methotrexate, antiretrovirals, hydroxycarbamide
  • disordered liver function
  • hypothyroidism
  • myelodysplasia

Haematology (12 decks)

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