Haematological Disorders Flashcards
When is HbF very low in healthy children - when is it not?
By age 1
Increased proportions of HbF are indicators of severe inherited disorders of haemoglobin production - haemoglobinopathies
Hb at birth
14-21.5g/dl to compensate for low oxygen concentration in fetus
What happens to Hb after birth
Falls over first few weeks of life, mainly due to reduced red cell production, to 10g/dl at 2 months of age
What happens to Hb after birth in pre-term babies?
It has a steaper fall to a mean of 6.5-9g/dl at 4-8 weeks chronological age
What are the iron, B12 and folic acid stores like in term and preterm infants at birth and after birth?
Iron, B12 and folic acid are adequate at birth in term and preterm babies
However in preterm babies stores of iron and folic acid are lower and are depleted more quickly leading to deficiency after 2-4months if recommended daily intakes are not maintained by supplements
Anaemia value in neonate
Hb less than 14g/dl
Anaemia value in 1-12months old
Hb less than 10g/dl
Anaemia value in 1-12 years
Hb less than 11g/dl
What is red cell aplasia
Complete absence of red cell production
What is ineffective erythropoeisis?
Red cell production is normal/increased rate but differentiation or survival of red cells is defective
What are the main causes of iron deficiency anaemia x3
Inadequate intake (common in infants)
Malabsorption
Blood loss
Which milk is not good for maintaining infant iron levels?
Cows milk because it has a higher iron content than breast milk but only 10% of the iron is absorbed
Therefore infants should not be fed unmodified cows milk
At what Hb level do children become symptomatic with anaemia?
6-7g/dl
How do children with iron deficiency anaemia present?
Pica- eating non-food materials such as soil, chalk, gravel or foam rubber
What are indicators on blood tests of iron deficiency anaemia
Microcytic, hypochromic anaemia (low MCV and MCH)
Low serum ferritin
Management of iron deficiency anaemia in infants?
Increase oral iron intake with supplementation - Sytron or Niferex are best tolerated preparations
Or just increase iron rich foods
What are the 3 main causes of red cell aplasia in children?
1) Diamond-Blackfan anaemia - congenital red cell aplasia
2) Transient erythroblastopenia of childhood
3) Parvovirus B19 infection in children with haemolytic anaemia
Diagnostic features of red cell aplasia x4
Low reticulocyte count despite normal Hb
Normal bilirubin
Negative direct antiglobulin/Coombs test
Absent red cell precursors on bone marrow examination
What is Diamond-Blackfan anaemia?
It is a rare congenital disease of red cell aplasia
Inheritance of Diamond-Blackfan anaemia
20% family history - remaining 80% are sporadic mutations
RPS (ribosomal protein) genes implicated in some cases
Presentation of Diamond-Blackfan anaemia
Most present at 2-3 months of age but 25% present at birth
Features of Diamond-Blackfan anaemia x2
Anaemia
Also congenital abnormalities such as short stature or abnormal thumbs
Treatment of Diamond-Blackfan anaemia x2
Oral steroids
Monthly red cell transfusions for children not responsive to steroids
What is transient erythoblastopenia of childhood?
Red cell aplasia usually triggered by viral infections
Same haemotological features as D-Blackfan anaemia
Prognosis of transient erythroblastopenia of childhood
Always recovers - usually within several weeks (hence differs from d-blackfan)
Inheritance of transient erythroblastopenia of childhood
No family history
When does haemolysis lead to anaemia?
When the bone marrow can no longer increase red cell production to compensate for the premature destruction of red cells
Main causes of haemolytic anaemias in children? What is uncommon children
Intrinsic abnormalities of RBCs (membrane and enzyme disorders and haemoglobinopathies)
Immune haemolysis is uncommon
What does haemolysis from increased RBC breakdown lead to? x4
Anaemia
Hepatomegaly and splenomegaly
Increased blood levels of unconjugated bilirubin
Increased urinary urobilinogen
Diagnostic clues to haemolytic anaemia x4
Increased reticulocyte count
Unconjugated bilirubinaemia and urinary urobilinogen
Abnormal appearance of red blood cells on film (spherocytes, sickle shaped or very hypochromic)
Increased red blood cell precursors in bone marrow
Incidence of hereditary spherocytosis
1 in 5000 live births in caucasians
Inheritance of hereditary spherocytosis
Usually autosomal dominant inheritance - BUT in 25% there is no family history and it is sporadic mutation
What is pathology of hereditary spherocytosis?
Mutation in gene for protein in red blood cell membrane - therefore RBC looses part of its membrane when it goes through the spleen
Therefore reduced surface-to-volume ratio and cell becomes spherical
Therefore less deformable than normal RBC and destruction of microvasculature of spleen
What are the clinical features of hereditary spherocytosis? x5
Clinical manifestations vary and patients can be completely asymptomatic or present during childhood or be intermittent - but can have:
- Jaundice
- Anaemia
- Mild-moderate splenomegaly
- Aplastic crisis with parvovirus B19
- Gallstones
Management of hereditary spherocytosis x2
Many have mild and therefore only require folic acid supplementation
Splenectomy is beneficial but only indicated if poor growth or troublesome symptoms - usually deferred until after 7 years old because of risk of sepsis
Management of aplastic crisis in hereditary spherocytosis
Usually requires 1 or 2 blood transfusions over 3-4 weeks whilst no red blood cells are produced
What is incidence of Glucose-6-phosphate dehydrogenase deficiency?
G6PD is commonest red cell enzymopathy - affects 100million people worldwide
10-20% of individuals from central africa, mediterranean and the middle east and far east
What is pathology of G6PD deficiency?
G6PD is an enzyme required to prevent oxidative damage to red cells - therefore red cells lacking the enzyme are susceptible to oxidant-induced haemolysis
Inheritance of G6PD deficiency?
It is x-linked therefore predominantly affects males. Heterozygous females are usually clinically normal and homozygous females (or one deletion + one mutation) will be affected
Clinical presentation of G6PD in children x2
1) Neonatal jaundice - onset in first 3 days of life - severe
2) Acute haemolysis precipitated by infection, certain drugs, fava beans (broad beans) and naphthalene (mothballs)
Details of haemolysis in G6PD - where does it occur and what does it cause x4
Mostly intravascular
Causes fever, malaise, passage of dark urine
Rapid fall in Hb
Diagnosis of G6PD
Between episodes almost all patients have a completely normal blood picture therefore diagnosis by looking at G6PD activity
During an episode G6PD may be misleadingly high due to increased reticulocyte production
Management of G6PD
Parents should be given advice about signs of acute haemolysis and provided with a list of what to avoid
Transfusions are rarely required even for acute episodes
When do B-thalassaemias present?
Delayed until after 6months of age when most of HbF (no B chains) has been replaced by HbA (with B chain)
Prevalence of sickle cell disease
1 in 2000 live births in UK
What does sickle cell disease encompass?
Sickle cell anaemia, sickle cell trait, HbSC disease and Sickle B-thalassaemia
What is HbSC disease?
One HbS and one HbC from other parent - HbC is point mutation in B-globin therefore also have no HbA
Features of sickle B-thalassaemia
Also have no normal B chains therefore no HbA and similar symptoms to sickle cell anaemia
Features of sickle cell trait?
About 40% HbS - do not have symptoms but are carriers and can pass on to children
Pathology of sickle
HbS polymerises forming stiff sickle shape with can get trapped in microcirculation - causing vaso-occlusion and therefore ischaemia
Exacerbated by low O2 tension, dehydration and cold
Clinical features of sickle x7
Anaemia (moderate 6-10g/dl) Infection Painful vaso-occlusive crises Acute anaemia (eg. in crises) Priapism Splenomegaly Long term problems
Types of infection risk in sickle
Infection from encapsulated organisms such as pnemococci and haemophilus influenzae
Increased osteomyelitis by salmonella
Due to hyposplenism and microinfarction in spleen in infancy
When is sepsis risk greatest in sickle
In early childhood - post-spleen destruction in infancy
Where is most commonly affected in painful crises of sickle x2
Bones of limbs and spines
Chest most serious as leads to hypoxia
What can cause acute anaemia in sickle? x3
Haemolytic crises (sometimes associated with infections) Aplastic crises (B19) Sequestration crises (sudden splenic or hepatic enlargement due to accumulation of sickled cells in spleen)
What needs to be done if priaprism in sickle
Urgent treatment with exchange transfusion as may lead to fibrosis in corpora cavernosa and erectile impotence
What age is splenomegaly common in sickle?
Common in younger children but not older children
What are long-term problems for sickle?x 6
Stroke and cognitive problems
Adenotonsillar hypertrophy - causing sleep aponea syndrome
Cardiac enlargement, heart failure - from anaemia
Renal dysfunction
Pigment gallstones
Leg ulcers
Prophylaxis in sickle? x3
Fully immunised against pneumococcal, haem infl type B and meningococcus infections
Daily oral penicillin throughout childhood
Folic acid
Lifestyle managements in sickle
Avoid cold, dehydration, excessive exercise, undue stress or hypoxia
Treatment of acute sickle crisis x4
Oral or IV analgesia
Good hydration
Antibiotics for infection
Oxygen if O2 sats reduced
Which 3 acute sickle crisis require exchange transfusion in sickle?
Priaprism, acute chest crisis and stroke
Common painful presentation of sickle in childhood?
Hand-foot syndrome due to dacylitis causing swelling and pain in fingers and/or feet from vaso-occlusion
Management for children with recurrent sickle crises? x2
Hydroxyurea which increases HbF concentration
requires monitoring for white blood cell suppression
If this doesn’t work then bone marrow transplant can be offered
Cure rate in sickle with bone marrow transplant
Cure rate is 90%
5% risk of fatal transplant-rated complications
How is sickle diagnosed early
Guthrie heelprick test at birth
SC disease difference from sickle anaemia x3
Have fewer painful crises but may develop proliferative retinopathy in adolescence - therefore check eyes periodically
Also prone to osteonecrosis of hips and shoulders
Where is B-thalassaemia common
Indian subcontinent, mediterranean and middle east
Two different types of b-thalassaemia?
Major and intermedia- intermedia is milder
Clinical features of b-thalassaemia x3
Severe anaemia - transfusion dependant from 3-6months of age
Failure to thrive/grow
Extramedullary haemopoiesis - prevented by transfusions but if no transfusions then hepatosplenomegaly and bone marrow expansion - classic facies with maxillary overgrowth and frontal bossing
Management of b-thalassaemia
Lifelong transfusions
Can lead to iron overload therefore iron chelation with desferrioxamine or deferasirox from age 2-3
Cure for b-thalassaemia
Bone marrow transplantation (90-95% success with HLA matched identical twin)
B-thalassaemia trait features x3
Usually asymptomatic
Hypochromic and microcytic red cells
Anaemia mild or absent
What happens in a-thalassaemia major
All four a-globin genes are deleted therefore hydrops fetalis - death in utero or within hours of birth
Can only survive with intrauterine transfusions and then lifelong
What happens in HbH disease - a-thalassaemia
Three a-globin chains deleted
Mild-moderate anaemia but occasionally they are transfusion dependant
Features of alpha-thalassaemia trait
1 or 2 chain deletions
Usually asymptomatic
Anaemia is mild or absent
What can b and a-thalassaemia traits be confused with?
Diagnostically they can be confused with mild iron deficiency
What is immune haemolytic anaemia of the newborn due to?
Antibodies against blood group antigens - most important are anti-D, anti-A or anti-B (ABO blood group)
Mother is always negative and baby is always positive therefore mother makes antibodies against baby’s blood group
Diagnostic tool for immune haemolytic anaemia
Coombs test (direct anti-globulin) positive - only positive in antibody mediated anaemias
Which haemolytic anaemias commonly present in neonatal period
Mostly due to G6PD deficiency or hereditary spherocytosis
Haemoglobinopathies rarely present with clinical features in neonatal period (but are detected on Guthrie)
What is aplastic anaemia?
Bone marrow failure
- reduction or absence of all 3 main lineages in bone marrow
What does aplastic anaemia lead to?
Peripheral blood pancytopenia - reduction of all blood cell types
What causes aplastic anaemia?
Many are “idiopathic” because specific cause cannot be found
Some can be inherited
Some can be acquired (viruses eg. hepatitis, drugs or toxins)
Clinical presentation of aplastic anaemia? x3
Anaemia due to reduced RBC
Infection due to reduced WBC
Bruising and bleeding due to thrombocytopenia
What is Fanconi anaemia?
Most common inherited aplastic anaemia
Inheritance of Fanconi anaemia?
Autosomal recessive condition
Clinical features of Fanconi anaemia other than directly due to blood cells?
Majority of children also have congenital abnormalities including short stature, abnormal radii and thumbs, renal malformations and pigmented skin lesions
How does Fanconi anaemia present?
Can present either with signs of bone marrow failure (not usually until age 5-6) or congenital abnormalities
Management of Fanconi anaemia?
Bone marrow transplantation from healthy sibling because can progress to acute myeloid leukaemia
What is Shwachman-Diamond syndrome?
Rare bone marrow failure - autosomal recessive disorder
What features are present in Shwachman-Diamond syndrome? x3
Signs of bone marrow failure
Also pancreatic exocrine failure and skeletal abnormalities
Risk with Fanconi anaemia and Shwachman-Diamond syndrome?
Both can advance to acute leukaemia
What is a good way to establish if new onset bleeding disorder is acquired or inherited?
If previous surgical procedures or dental extractions were uncomplicated - suggests acquired
What sort of bleeding disorder is associated with mucous membrane bleeding and skin haemorrhage?
Platelet disorders or von Willebrand disease
What sort of bleeding disorder is associated with bleeding into muscles or joints?
Haemophilia
What sort of disorder is associated with scarring and delayed haemorrhage
Disorders of connective tissue such as Marfans syndrome, osteogenesis or factor XIII deficiency
Clotting factors in neonate?
Levels of all (except FVIII and fibrinogen) are lower and preterm infants have even lower values - therefore have to compare with values for gestational age
How are haemophilia a and b inherited?
Both have x-linked recessive inheritance therefore only affect males
Deficiency in haemophilia a
FVIII deficiency
Deficiency in haemophilia b
FIX deficiency
Which haemophilia is more common
haemophilia a is a lot more common
Different types of both haemophilias
Disorder is graded as severe, moderate or mild
Features of severe haemophilia
Recurrent spontaneous bleeding into joints and muscles - leads to crippling arthritis if not properly treated
Present usually towards end of 1st year when starting to crawl and walk
How can haemophilia present if presents before crawling/walking age?
Can present in neonatal period (40%) with intracranial haemorrhage, bleeding post-circumcision or prolonged oozing from heel prick and venepuncture sites
Inheritance of severity of haemophilia?
Severity usually remains constant within a family
Acute management of haemophilia
Recombinant factor VIII or IX is given IV whenever there is acute bleeding
Usually raising level to 30% of normal is enough
When do factor levels need to be raised above 30% of normal in haemophilia?
Major surgery or life threatening bleeds - require raising to 100% and then maintained at 30-50% for 2 weeks to prevent secondary bleed
Prophylactic treatment for severe haemophilia a
Prophylactic FVIII - usually begins at age 2-3 years, given 2/3x per week
Prophylactic treatment of mild haemophilia a
Desmopressin may allow mild haemophilia a to be managed without blood products
Ineffective in haemophilia b
What is von Willebrand disease?
Quantitative or qualitative deficiency of vWF
What does vWF do? x2
Faciliates platelet adhesion to damaged endothelium
Acts as carrier protein for FVIII
Pathology of vWD?
Defective platelet plug formation and also deficient in FVIII
Inheritance of vWD?
Autosomal dominant
Presentation age of vWD?
Commonest subtype - type 1 (60-80%) usually fairly mild and often not diagnosed until puberty or adulthood
Clinical features of vWD? x3
Bruising
Excessive, prolonged bleeding after surgery
Mucosal bleeding such as epistaxis and menorrhagia
Management of mild vWD?
Mild can often be managed with desmopressin
When do you need to be careful using desmopressin?
Need to be used with caution in children under 1 because can cause hyponatraemia due to water retention and may cause seizures if fluid intake is not strictly regulated
Treatment of more severe vWD?
Treated with plasma derived FVIII concentrate (recombinant does not contain vWF therefore no good)
What should be avoided in haemophilia and vWD patients? x3
IM injections, aspirin and NSAIDs
What is the definition of thrombocytopenia?
Platelet count below 150 x10-9/L
Definition and presentation of severe thrombocytopenia
Platelets below 20 x 10-9/l
Risk of spontaneous bleeding
Definition and presentation of moderate thrombocytopenia
Platelets 20-50
Risk of excess bleeding during operations or trauma but low risk of spontaneous bleeding
Definition and presentation of mild thrombocytopenia
Platelets 50-150
Low risk of bleeding unless there is a major operation or severe trauma
What can thrombocytopenia result in? x4
Bruising, petechiae, purpura, mucosal bleeding (nose, gums)
What is immune thrombocytopenia? (ITP)
Commonest cause of thrombocytopenia in childhood - caused by destruction of circulating platelets by antiplatelet IgG autoantibodies
Typical presentation of ITP and age
Present between ages of 2 and 10 with onset often 1-2 weeks after viral infection
Clinical features of ITP x5
Most children have a short history of days/weeks of
Petechiae, purpura and/or superficial bleeding
Can also cause mucosal bleeding and epistaxis
Rare complication of ITP
Intracranial bleeding - rare but serious - mainly in those with a long period of severe thrombocytopenia
Diagnosis of ITP
Diagnosis of exclusion
Examine bone marrow to exclude aplastic anaemia or leukaemia
Management of ITP
80% of children have benign self-limiting disease - remitting within 6-8 weeks
But if persistent bleeding then oral prednisolone, IV anti-D or IV immunoglobulin
Platelet transfusions only for life-threatening haemorrhage
What is chronic ITP
20% in whom the platelet count remains low 6months after diagnosis
Management of chronic ITP
Supportive mostly
Drugs only for chronic bleeding
Monoclonal antibodies and other new drugs
What is disseminated intravascular coagulation? (DIC)
Disorder characterised by coagulation pathway activation leading to fibrin deposition in microvasculature and consumption of coag factors and platelets and therefore bleeding
Commonest causes of DIC x3
Severe sepsis or shock due to circulatory collapse (meningococcal septicaemia), or extensive tissue damage from trauma or burns
Clinical features of DIC x3
Bruising, purpura and haemorrhage
Management of DIC
Treat underlying cause whilst providing intensive care
Can give fresh frozen plasma, platelets and cryoprecipitate
EG’s of prothrombotic disorders x4
Protein C and S deficiency
Antithrombin deficiency
Factor V Leiden
When do prothrombotic disorders present?
C and S heterozygotes - mostly in second or third decade and rarely in childhood
C and S homozygotes rare - thrombosis and widespread haemorrhage and purpura in neonatal period
Most common cause of thrombosis in children
95% of venous thromboembolic events in childhood are secondary to underlying disorder with hypercoagulable state
