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when is beta thalassaemia usually diagnosed?
1st year of life
why is the neonate hardly affected by beta thalassaemia?
because it has HbF (alpha and gamma chains only, no beta chains)
which people does beta thal occur in more?
- indian subcontinent
- middle east
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
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
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
what causes thal major?
- auto recessive
- mutations in all beta globin genes
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
what is the mainstay of Rx of beta thal major?
lifelong monthly transfusions of RBC
what are main aims of Rx of beta thal?
- Hb > 10g/dL
- to reduce growth failure
- prevent bone deformation
what are the SE of repeat blood transfusion?
- iron overload
- cardiac failure
- liver cirrhosis
- infertility - due to pit gland
- growth failure due to pituitary gland
- skin - hyperpigmentation (bronze skinned diabetes)
what is done to minimise chronic iron overload?
- iron chelation therapy - desferrioxamine overnight
- start at age 2-3yo
what is cause of death in beta thal major?
non compliance with iron chelation therapy - causes iron overload (cardiac death)
what is the only cure for beta thal major?
- BM transplant
- only for children with HLA identical sibling
what does the blood film in beta thal trait look like?
- hyopchromic, microcytic RBC
- anaemia is mild/absent - disproportionate reduction in MCH/MCV
what is the most important diagnostic feature of Beta thal TRAIT?
increased HbA2 on HbF
what can beta thal trait be confused with and why is this bad?
- confused with mild IDA
- lead to unnecessary iron therapy
what type of vasculitis is Henoch Schonlein purpura?
multisystem small vessel vasculitis
which organs does HSP affect?
skin, joints, GI, kidney
what is HSP also known as?
what age does HSP affect?
2-11 years old
is HSP more in boys or girls?
- boys (even though autoimmune!)
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
which other disease does HSP have an overlap with?
what time of year is HSP more frequent in?
what are the trigger agents for HSP?
- infectious agents - URTI
- insect bites
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
differential diagnosis of HSP
- other cause of abdominal pain
- other causes of purpuric or petechial pain eg ITP
how is diagnosis of HSP made?
what are the useful Ix for HSP?
- FBC - normal platelet count rules out ITP
- renal funciton U&E
- US abdo - rule out intussecption
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
what is prognosis of HSP
majority full recovery in 4-6 weeks
what does long term prognosis of HSP depend on?
presence and severity of NEPHRITIS
why do you have to follow up HSP for prolonged period?
to monitor renal function
what % of pts with HSP progress to end stage renal failure
only 1% pts progress to end stage renal disease
what is the cut off for thrombocytopenia?
platelets < 150 x 10x9
what is the most common cause of thrombocytopenia in children?
ITP - idiopathic thrombocytopenic purpura
what is the cause of ITP?
- but immune mediated - anti-platelet antibodies
- happens 1-2 weeks after viral infection
as a compensatory mechanism to reduced platelet, what increases in the BM?
what is the peak age of ITP?
2-10 years old
what are the features of ITP?
- superficial bleeding
- bleeding from mucosal surfaces eg epistaxis
- spleen palpable in some cases
where are the platelets destroyed in ITP?
reticuloendothelial system - mainly spleen
what is a complication of ITP?
- intracranial bleed
- but only if long period of severe thrombocytopenia
what is the differential diagnosis of ITP?
- Henoch Schonlein Purpura
- Acute Leukaemia
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
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
why are platelet transfusions not effective, when used?
- not effective as they will be destroyed
- use if life threatening emergency
why is serious bleeding rare?
as platelets function more efficiently
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
if medical therapy fails what is the next option?
which children (age and sex) have a higher risk of chronic disease?
what is chronic ITP?
low platelets for 6 months after diagnosis
what is treatment for ITP?
- no steroids
- avoid contact sports, but encouraged to continue normal activity eg school
- 24h access to hospital
- ITP Support Group
what happens to most children with chronic ITP?
remit within 3 years from onset or stabilise with moderate asymptomatic thrombocytopenia
if ITP in a child becomes chronic, what needs to be screened for?
what is the commonest cause of anaemia in childhood?
how long do term infants have iron reserves for?
how long do preterms have iron reserves for?
by 8 weeks gone as higher rate of growth
what % of iron is absorbed from breast milk?
what % of iron is absorbed from unmodified cows milk?
what are dietary sources of iron?
- red meat, liver, kidney, oily fish eg sardines
- dark green veg eg spinach, broccoli
- fortified cereals
what can enhance iron absorption?
what can reduce Iron absorption?
tannin in tea
apart from diet what are other causes of IDA?
- repeat venesection
- meckels diverticulum
what are symptoms of severe anaemia?
what are long term consequences of iron deficiency?
- developmental delay
- behaviour problems
- low IQ
- growth problems
how is diagnosis of anaemia confirmed?
FBC, blood film, iron stores
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
how long is Rx for IDA?
- continue for another 3 months AFTER correction of anaemia
- to allow replenishment of stores
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
what causes haemophilia A? and what is inheritance?
- factor 8 deficiency
- x linked recessive
what are symptoms of haemophilia A?
- spontaneous or traumatic bleeding
- skin, muscle joints
what is the APTT in haemophilia A?
- indicating defect in INTRINSIC pathway
what is Rx of haemophilia A?
- replace factor 8
- IV infusion
how can mild haemophilia A be treated?
infusion of desmopressin that releases factor 8 from tissue stores
what is the other name of haemophilia B? what is it?
- christmas disease
- x linked recessive
- factor 9 deficiency
what is Rx of haemophilia B?
prothrombin complex concentrate
what are the 2 major roles of von willebrand factor?
- carrier protein for F8 - prevent from being broken down
- platelet adhesion
what is inheritance of VW disease?
- auto dominant
- variable penetrance
what is main feature of von willebrand disease?
- bleeding into skin
- mucous membrane - gums