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when is beta thalassaemia usually diagnosed?
1st year of life
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why is the neonate hardly affected by beta thalassaemia?
because it has HbF (alpha and gamma chains only, no beta chains)
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which people does beta thal occur in more?
- indian subcontinent
- mediterranean
- middle east
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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
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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
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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
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what causes thal major?
- auto recessive
- mutations in all beta globin genes
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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
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what is the mainstay of Rx of beta thal major?
lifelong monthly transfusions of RBC
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what are main aims of Rx of beta thal?
- Hb > 10g/dL
- to reduce growth failure
- prevent bone deformation
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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)
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what is done to minimise chronic iron overload?
- iron chelation therapy - desferrioxamine overnight
- start at age 2-3yo
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what is cause of death in beta thal major?
non compliance with iron chelation therapy - causes iron overload (cardiac death)
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what is the only cure for beta thal major?
- BM transplant
- only for children with HLA identical sibling
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what does the blood film in beta thal trait look like?
- hyopchromic, microcytic RBC
- anaemia is mild/absent - disproportionate reduction in MCH/MCV
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what is the most important diagnostic feature of Beta thal TRAIT?
increased HbA2 on HbF
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what can beta thal trait be confused with and why is this bad?
- confused with mild IDA
- lead to unnecessary iron therapy
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what type of vasculitis is Henoch Schonlein purpura?
multisystem small vessel vasculitis
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which organs does HSP affect?
skin, joints, GI, kidney
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what is HSP also known as?
anaphylactoid purpura
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what age does HSP affect?
2-11 years old
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is HSP more in boys or girls?
- boys (even though autoimmune!)
- 2:1
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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
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which other disease does HSP have an overlap with?
IgA nephropathy
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what time of year is HSP more frequent in?
winter
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what are the trigger agents for HSP?
- infectious agents - URTI
- drugs
- food
- insect bites
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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
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differential diagnosis of HSP
- other cause of abdominal pain
- other causes of purpuric or petechial pain eg ITP
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how is diagnosis of HSP made?
clinical
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what are the useful Ix for HSP?
- FBC - normal platelet count rules out ITP
- renal funciton U&E
- US abdo - rule out intussecption
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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
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what is prognosis of HSP
majority full recovery in 4-6 weeks
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what does long term prognosis of HSP depend on?
presence and severity of NEPHRITIS
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why do you have to follow up HSP for prolonged period?
to monitor renal function
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what % of pts with HSP progress to end stage renal failure
only 1% pts progress to end stage renal disease
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what is the cut off for thrombocytopenia?
platelets < 150 x 10x9
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what is the most common cause of thrombocytopenia in children?
ITP - idiopathic thrombocytopenic purpura
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what is the cause of ITP?
- idiopathic!
- but immune mediated - anti-platelet antibodies
- happens 1-2 weeks after viral infection
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as a compensatory mechanism to reduced platelet, what increases in the BM?
megakaryocytes
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what is the peak age of ITP?
2-10 years old
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what are the features of ITP?
- petechiae
- purpura
- superficial bleeding
- bleeding from mucosal surfaces eg epistaxis
- spleen palpable in some cases
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where are the platelets destroyed in ITP?
reticuloendothelial system - mainly spleen
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what is a complication of ITP?
- intracranial bleed
- but only if long period of severe thrombocytopenia
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what is the differential diagnosis of ITP?
- Henoch Schonlein Purpura
- Acute Leukaemia
- NAI
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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
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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
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why are platelet transfusions not effective, when used?
- not effective as they will be destroyed
- use if life threatening emergency
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why is serious bleeding rare?
as platelets function more efficiently
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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
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if medical therapy fails what is the next option?
splenectomy
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which children (age and sex) have a higher risk of chronic disease?
teenage girls
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what is chronic ITP?
low platelets for 6 months after diagnosis
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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
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what happens to most children with chronic ITP?
remit within 3 years from onset or stabilise with moderate asymptomatic thrombocytopenia
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if ITP in a child becomes chronic, what needs to be screened for?
SLE
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what is the commonest cause of anaemia in childhood?
dietary IDA
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how long do term infants have iron reserves for?
4 months
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how long do preterms have iron reserves for?
by 8 weeks gone as higher rate of growth
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what % of iron is absorbed from breast milk?
50%
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what % of iron is absorbed from unmodified cows milk?
10%
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what are dietary sources of iron?
- red meat, liver, kidney, oily fish eg sardines
- dark green veg eg spinach, broccoli
- fortified cereals
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what can enhance iron absorption?
vit C
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what can reduce Iron absorption?
tannin in tea
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apart from diet what are other causes of IDA?
- hookworm
- malabsorption
- menstruation
- repeat venesection
- epistaxis
- meckels diverticulum
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what are symptoms of severe anaemia?
- lethargy
- irritable
- anorexia
- fatigue
- CCF
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what are long term consequences of iron deficiency?
- developmental delay
- behaviour problems
- low IQ
- growth problems
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how is diagnosis of anaemia confirmed?
FBC, blood film, iron stores
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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
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how long is Rx for IDA?
- continue for another 3 months AFTER correction of anaemia
- to allow replenishment of stores
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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
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what causes haemophilia A? and what is inheritance?
- factor 8 deficiency
- x linked recessive
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what are symptoms of haemophilia A?
- spontaneous or traumatic bleeding
- skin, muscle joints
- haemarthroses
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what is the APTT in haemophilia A?
- prolonged
- indicating defect in INTRINSIC pathway
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what is Rx of haemophilia A?
- replace factor 8
- IV infusion
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how can mild haemophilia A be treated?
infusion of desmopressin that releases factor 8 from tissue stores
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what is the other name of haemophilia B? what is it?
- christmas disease
- x linked recessive
- factor 9 deficiency
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what is Rx of haemophilia B?
prothrombin complex concentrate
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what are the 2 major roles of von willebrand factor?
- carrier protein for F8 - prevent from being broken down
- platelet adhesion
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what is inheritance of VW disease?
- auto dominant
- variable penetrance
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what is main feature of von willebrand disease?
- bleeding into skin
- mucous membrane - gums
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