paeds haematology Flashcards by Ismay Hathawau

What rhesus antigen causes haemolytic disease of the newborn?

rhesus D
(mother who is rhesus negative, baby who is rhesus positive)

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Pathophysiology of rhesus haemolytic disease

rhesus negative mother has rhesus positive child
If her blood is exposed to the fetal blood it will produce anti-D antibodies (sensitisation)
In future pregnancies these can cross the the placenta and causes fetal anaemia.

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what severe fetal emergency can occur in rhesus disease?

hydrops fetalis

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How does rhesus disease present

jaundice (Early within 24 hours)
pallor
hepatosplenomegaly
hydrops fetalis
heart failure

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how does hydrops fetalis present antinataly

polyhydramnios

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how does hydrops fetalis present postnataly

subcutaneous oedema
pericardial effusion
pleural effusion
ascites
hepatosplenomegaly

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What test is used to screen for rhesus disease during pregnancy

indirect coombs test- checks for antibodies to d in the maternal blood

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Genetics of sickle cell disease

autosomal recessive condition affecting the beta-globin on chromosome 11

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How does sickle cell disease present?

anaemia
increased risk of infection
sickle cell crisis- acute exacerbation, usually triggered by stress, cold weather, dehydration
Vaso-occlusive crisis- pain in hands or feet
priapism
Aplastic crisis
Acute chest syndrome

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How does ALL present on blood smear

blast cells

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How is von willebrands disease inherited

autosomal dominant (except type 3= recessive)

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what are the three types of von-willebrands disease

type 1- partial reduction of vWF
type 2- abnormal form of vWF
type 3- total lack of vWF

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what is the most common type of von willebrands disease

type 1 (80% of cases)

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pathophysiology of von willebrands disease

a reduction or abnormality in von willebrands factor- a large glycoprotein that promotes platelet adhesion to damaged endothelium
Is also a carrier molecule for factor VIII

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How does von willebrands disease present

epistaxis
menorrhagia
haemoarthrosis
muscle haematomas
easy bruising
GI bleeding
post natal haemorrhage

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diagnosis of von willebrands disease

prolonged bleeding time
APTT may be prolonged, PT and TT will be normal
factor VIII levels reduced
von willebrand functional assay

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how is von willebrand disease treated

tranexamic acid for mild bleeding
desmopressin
factor VIII concentrate

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how does desmopressin treat von willebrand disease

it raises the levels of vWF by inducing release of vWF from Weibel - palade bodies in the endothelial cells

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when does immune thrombocytopenic purpura commonly occur?

following a viral illness or immunisation

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pathophysiology of immune thrombocytopenic purpura
which receptors are effected?

it is a type II hypersensitivity reaction where the spleen produces antibodies against the glycoprotein IIb/IIIa or Ib-V-IX complex

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How does ITP present

purpura
petechiae
prolonged bleeding
mucocutaneous bleeding
heavy periods
blood in urine or stool

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How can you differentiate between ITP and ALL

ATP will just have low platelets on bloods whereas ALL shows pancytopenia

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what chemotherapy agents are used in ALL

vincristine
cyclophosphamide
doxorubicin
prednisolone

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what is the inheritance of haemophilia?

x linked recessive

what is haemophilia

an inherited bleeding disorder caused by a deficiency in a clotting factor

what two types of haemophilia are there?

haemophilia type A and type B

what factor is deficient in haemophilia type A

factor VIII (8)

what factor is deficient if haemophilia type B

factor IX (9)

How does haemophilia present?

haemarthrosis (bleeding into joints) oral mucosa bleeding epistaxis GI bleeding haematuria prolonged bleeding after trauma or surgery

how can haemophilia present in neonates

intracranial haemorrhage, haematomas, cord bleeding

how is haemophilia diagnosed?

APPT will be prolonged bleeding time, thombin time and prothrombin time will be normal Genetics

How is haemophilia treated>

infusion of the affected clotting factor (8 or 9)

what is complication that can occur with the treatment of haemophilia type A and how common is it?

antibodies can develop to the treatment - occurs in 30%

What can cause anaemia in infants

physiological anaemia anaemia of prematurity blood loss haemolysis (e.g. G6PD, Rhesus) twin to twin transfusion

Why does physiological anaemia occur in infants and when does it present?

at around 6-9 weeks. Occurs as neonates have a high Hb during birth which causes a negative feedback suppression of erythropoeisis.

Why does anaemia of prematurity occur?

- less time is spent in utero receiving mothers blood - RBC cannot keep up with growth - decreased erythropoeitin - multiple blood tests remove large proportions of blood

main causes of anaemia in older children

iron deficiency of anaemia and blood loss duirng menstruation are the most common causes Other: - sickle cell - thalassaemia, - leukaemia - hereditary spherocytosis - sideroblastic anaemia

what are some specific signs for iron deficiency anaemia?

pica hair loss kolionychia angular chellitis atrophic glossitis brittle hair and nails

what drug can cause iron deficiency anaemia and why?

PPIs- iron needs acid from the stomach to keep it soluble to carry it to the duodenum and jejunum where it is absorbed PPI's cause a decrease stomach acid.

what are some causes of iron deficiency anaemia

helminth infections menstrual loss poor diet poor absorption (e.g. Crohn's)

What is thalassaemia?

an inherited disorder where the body does not produce enough of one of the two haemoglobin chains

what is the inheritance of thalassaemia

autosomal recessive

what are the two forms of thalassaemia and what chromosome is associated with each?

alpha - chromosome 16 beta - chromosome 11

what three types of beta thalassaemia are there?

minor- carrier of the gene intermedia- two defective gene or one deleted and one defective major- two deleted genes

What test can be used to check how much fetal blood has passed into the mothers, and hence determine if further anti-D is required?

Kleinhauer's test

explain the pathophysiology of alpha thalassaemia

there are 4 alleles for the alpha globin chain- two on each chromosome If 1-2 alleles are defective then the patient will usually be normal if 3 alleles are affected then the pateint has HbH disease and will need transfusions If 4 alleles then hydrops fetalis occurs in utero .

how is thalassaemia diagnosed?

haemoglobin electrophoresis

What is the treatment of thalassaemia

blood transfusions iron chelation bone marrow transplant

why does iron overload occur in thalassaemia

faulty RBC are broken down transfusions increase iron the gut increases iron absorption in response to anaemai

How does iron overload present?

liver cirrhosis infertility impotence HF diabetes arthritis osteoporosis

What can be used to treat iron overload in thalassaemia

desferrioxamine

how does thalassaemia present?

anaemia jaundice extramedullary haematopoeisis (pronounced forehead and malar eminences) hepatosplenomegaly

What is fetal haemoglobin made up of

two alpha and two gamma chains

what is fanconi anaemia

an inherited bone marrow failure syndrome

inheritence of fanconi anaemia

autosomal recessive

How does fanconi anaemia present?

haem features- aplastic anaemia (bleeding, infections etc) neurological symptoms skeletal signs (short, thumb abnormalities) cafe au lait spots solid tumours (liver, neck, oesophageal )

what haem cancer is associated with fanconi anaemia

AML