Haematology.txt

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kavinashah
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93566
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Haematology.txt
Updated:
2011-07-10 19:52:05
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paed haem
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pead haem
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  1. when is beta thalassaemia usually diagnosed?
    1st year of life
  2. why is the neonate hardly affected by beta thalassaemia?
    because it has HbF (alpha and gamma chains only, no beta chains)
  3. which people does beta thal occur in more?
    • indian subcontinent
    • mediterranean
    • middle east
  4. what do you see on Hb electrophoresis in beta thal?
    • HbA low - as deficiency of B-chains
    • HbF high
    • HbA2 - increasing as more delta chain production
  5. what happens to the red cells in beta thal?
    • get ineffective erythropoiesis (cell death in BM due to globin chain precip
    • premature removal of circulating red cells by spleen
  6. what determines the severity of beta thal?
    • amount of HbA and HbF present
    • major: most severe form, HbA cannot be produced due to abnormal B-globin gene
    • intermedia: B-globin mutations allow small amount of HbA to be formed and also lots of HbF. milder thal
    • trait: one normal and one abnormal B-globin gene. asymptomatic carrier
  7. what causes thal major?
    • auto recessive
    • mutations in all beta globin genes
  8. what are clinical features of b thal major?
    • severe anaemia and jaundice from 6months
    • failure to thrive
    • extramedullary haemopoiesis - get BM expansion - maxillary overgrowth and skull bossing, hepatosplenomegaly
  9. what is the mainstay of Rx of beta thal major?
    lifelong monthly transfusions of RBC
  10. what are main aims of Rx of beta thal?
    • Hb > 10g/dL
    • to reduce growth failure
    • prevent bone deformation
  11. what are the SE of repeat blood transfusion?
    • iron overload
    • cardiac failure
    • liver cirrhosis
    • diabetes
    • infertility - due to pit gland
    • growth failure due to pituitary gland
    • skin - hyperpigmentation (bronze skinned diabetes)
  12. what is done to minimise chronic iron overload?
    • iron chelation therapy - desferrioxamine overnight
    • start at age 2-3yo
  13. what is cause of death in beta thal major?
    non compliance with iron chelation therapy - causes iron overload (cardiac death)
  14. what is the only cure for beta thal major?
    • BM transplant
    • only for children with HLA identical sibling
  15. what does the blood film in beta thal trait look like?
    • hyopchromic, microcytic RBC
    • anaemia is mild/absent - disproportionate reduction in MCH/MCV
  16. what is the most important diagnostic feature of Beta thal TRAIT?
    increased HbA2 on HbF
  17. what can beta thal trait be confused with and why is this bad?
    • confused with mild IDA
    • lead to unnecessary iron therapy
  18. what type of vasculitis is Henoch Schonlein purpura?
    multisystem small vessel vasculitis
  19. which organs does HSP affect?
    skin, joints, GI, kidney
  20. what is HSP also known as?
    anaphylactoid purpura
  21. what age does HSP affect?
    2-11 years old
  22. is HSP more in boys or girls?
    • boys (even though autoimmune!)
    • 2:1
  23. what is the cause of HSP?
    • exact unknown
    • immunopathological involvement
    • increased IgA in serum
    • make complexes, activate complement and deposited in affected organs
    • precipitate an inflammatory response with vascultiis
  24. which other disease does HSP have an overlap with?
    IgA nephropathy
  25. what time of year is HSP more frequent in?
    winter
  26. what are the trigger agents for HSP?
    • infectious agents - URTI
    • drugs
    • food
    • insect bites
  27. what are the clinical features of HSP?
    • purpuric rash - but initially urticarial. affecting predominantly extensors (buttocks, legs) symmetrical
    • arthritis with pain and swelling - knees and ankles
    • cramping abdominal pain, GI bleed - complication intussusception ileoileal
    • renal: haematuria, proteinuria in a minority of patients. can be severe. clinical glomerulonephritis or nephrotic syndrome
  28. differential diagnosis of HSP
    • other cause of abdominal pain
    • other causes of purpuric or petechial pain eg ITP
  29. how is diagnosis of HSP made?
    clinical
  30. what are the useful Ix for HSP?
    • FBC - normal platelet count rules out ITP
    • renal funciton U&E
    • US abdo - rule out intussecption
  31. what is Rx of HSP?
    • symptomatic and supportive
    • paracetamol or NSAIDs control pain
    • oral steroids occasional used if severe abdominal pain but ensure intussesception not present
  32. what is prognosis of HSP
    majority full recovery in 4-6 weeks
  33. what does long term prognosis of HSP depend on?
    presence and severity of NEPHRITIS
  34. why do you have to follow up HSP for prolonged period?
    to monitor renal function
  35. what % of pts with HSP progress to end stage renal failure
    only 1% pts progress to end stage renal disease
  36. what is the cut off for thrombocytopenia?
    platelets < 150 x 10x9
  37. what is the most common cause of thrombocytopenia in children?
    ITP - idiopathic thrombocytopenic purpura
  38. what is the cause of ITP?
    • idiopathic!
    • but immune mediated - anti-platelet antibodies
    • happens 1-2 weeks after viral infection
  39. as a compensatory mechanism to reduced platelet, what increases in the BM?
    megakaryocytes
  40. what is the peak age of ITP?
    2-10 years old
  41. what are the features of ITP?
    • petechiae
    • purpura
    • superficial bleeding
    • bleeding from mucosal surfaces eg epistaxis
    • spleen palpable in some cases
  42. where are the platelets destroyed in ITP?
    reticuloendothelial system - mainly spleen
  43. what is a complication of ITP?
    • intracranial bleed
    • but only if long period of severe thrombocytopenia
  44. what is the differential diagnosis of ITP?
    • Henoch Schonlein Purpura
    • Acute Leukaemia
    • NAI
  45. what Ix are to be done in suspected ITP?
    • FBC - should not be pancytopenia
    • Bone marrow aspiration - exclude marrow infiltration - only if doubt about diagnosis (eg if hepatosplenomeg or lymphadenopathy) or starting steroid (as may mask other sinister causes). will see increased megakaryocytic
  46. what is the Rx of most children?
    • most - disease is acute, benign and self limiting - no therapy needed (even at platelet level <10)
    • IvIg or steroids
    • IvIg: cause more rapid rise in platelets, use in severe disease
    • steroids - only as short course (SE) - always examine BM first to exclude ALL
  47. why are platelet transfusions not effective, when used?
    • not effective as they will be destroyed
    • use if life threatening emergency
  48. why is serious bleeding rare?
    as platelets function more efficiently
  49. what advice is given to parents in ITP
    • need 24 hours immediate access to hospital
    • child avoid trauma and contact sports while plt count v.low
  50. if medical therapy fails what is the next option?
    splenectomy
  51. which children (age and sex) have a higher risk of chronic disease?
    teenage girls
  52. what is chronic ITP?
    low platelets for 6 months after diagnosis
  53. what is treatment for ITP?
    • no steroids
    • supportive
    • avoid contact sports, but encouraged to continue normal activity eg school
    • 24h access to hospital
    • ITP Support Group
  54. what happens to most children with chronic ITP?
    remit within 3 years from onset or stabilise with moderate asymptomatic thrombocytopenia
  55. if ITP in a child becomes chronic, what needs to be screened for?
    SLE
  56. what is the commonest cause of anaemia in childhood?
    dietary IDA
  57. how long do term infants have iron reserves for?
    4 months
  58. how long do preterms have iron reserves for?
    by 8 weeks gone as higher rate of growth
  59. what % of iron is absorbed from breast milk?
    50%
  60. what % of iron is absorbed from unmodified cows milk?
    10%
  61. what are dietary sources of iron?
    • red meat, liver, kidney, oily fish eg sardines
    • dark green veg eg spinach, broccoli
    • fortified cereals
  62. what can enhance iron absorption?
    vit C
  63. what can reduce Iron absorption?
    tannin in tea
  64. apart from diet what are other causes of IDA?
    • hookworm
    • malabsorption
    • menstruation
    • repeat venesection
    • epistaxis
    • meckels diverticulum
  65. what are symptoms of severe anaemia?
    • lethargy
    • irritable
    • anorexia
    • fatigue
    • CCF
  66. what are long term consequences of iron deficiency?
    • developmental delay
    • behaviour problems
    • low IQ
    • growth problems
  67. how is diagnosis of anaemia confirmed?
    FBC, blood film, iron stores
  68. what is Rx of IDA?
    • dietary advice: see dietician and inc iron rich food, avoid cows milk, more breast or formula as had added iron
    • oral iron supplements eg sodium iron edentate
  69. how long is Rx for IDA?
    • continue for another 3 months AFTER correction of anaemia
    • to allow replenishment of stores
  70. if there is a failure of response to Rx or recurrence despite adequate intake of iron, what is to be done?
    Ix for GI bleed
  71. what causes haemophilia A? and what is inheritance?
    • factor 8 deficiency
    • x linked recessive
  72. what are symptoms of haemophilia A?
    • spontaneous or traumatic bleeding
    • skin, muscle joints
    • haemarthroses
  73. what is the APTT in haemophilia A?
    • prolonged
    • indicating defect in INTRINSIC pathway
  74. what is Rx of haemophilia A?
    • replace factor 8
    • IV infusion
  75. how can mild haemophilia A be treated?
    infusion of desmopressin that releases factor 8 from tissue stores
  76. what is the other name of haemophilia B? what is it?
    • christmas disease
    • x linked recessive
    • factor 9 deficiency
  77. what is Rx of haemophilia B?
    prothrombin complex concentrate
  78. what are the 2 major roles of von willebrand factor?
    • carrier protein for F8 - prevent from being broken down
    • platelet adhesion
  79. what is inheritance of VW disease?
    • auto dominant
    • variable penetrance
  80. what is main feature of von willebrand disease?
    • bleeding into skin
    • mucous membrane - gums

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