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paediatrics > Haematology > Flashcards

Haematology Flashcards

1
Q

Thalassaemia types where transfusions NOT required

A

Alpha thalassaemia trait Beta thalassaemia minor

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2
Q

Equation for tissue oxygen delivery

A

Tissue O2 delivery = CO x Hb x O2 sat x 1.34 CO = HR x SV

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3
Q

Causes of isolated prolonged APTT

A

Factor deficiency: VIII, IX, XII, XI, vWF Heparin in sample Antibodies in sample (most commonly lupus anticoagulant) What do you do? - Mix test 1:1 patients plasma + donor plasma. If factor deficiency will then normalise APTT.

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4
Q

Cause of isolated PT prolongation

A

Factor VII deficiency or Anticoagulant therapy (most commonly wafarin therapy)

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5
Q

Cause of neonate with delayed bleeding from umbilical cord day 5-14 of life with normal PT, APTT + fibrinogen

A

Factor XIII deficiency Factor XIII cross links fibrin forming a strong fibrin clot

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6
Q

Why should you order fibrinogen as a part of your coag screen?

A

PT + APTT only measures the coagulation cascade down to fibrin formation. If you do NOT have enough fibrinogen then the PT + APTT will be abnormal, not as a result of deficit higher up in the cascade but at the level of fibrinogen.

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7
Q

What blood product do you use if you have a fibrinogen deficiency?

A

Cryoprecipitate

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8
Q

DIC coag results DIC disease of the vascular endothelium

A

APTT: prolonged PT/INR: prolonged Fibrinogen: low or normal D dimers: elevated Plts: low

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9
Q

Liver disease (not producing factors) coag results

A

APTT: prolonged PT/INR: prolonged Fibrinogen: normal D dimers: normal Plts: normal unless portal HTN

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10
Q

Vitamin K deficiency coag results

A

APTT: prolonged PT/INR: prolonged Fibrinogen: normal D dimers: normal Plts: normal

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11
Q

PT vs INR

A

PT: thromboplastin used to activate factor VII and time how long it takes to form fibrin PT / PT ratio = INR

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12
Q

Vitamin K deficiency

A

Early: 48 hrs (usually due to maternal epileptics / antimetabolites) Classical: 48hrs- 7 days Late: 7 days - 9 months Formula has vitamin K in it

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13
Q

Causes of microcytic anaemia

A

TICLSS Thalassaemia Iron deficiency, infantile pokilocytosis Copper deficiency, chronic disease Lead poisoning Sideroblastic (XLR) Spherocytosis

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14
Q

Causes of normocytic anaemia

A

RACHAEL Renal disease Acute blood loss Chronic disease Haemolysis (inherited + acquired) Aplastic anaemia Erythroblastopenia of childhood Liver disease

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15
Q

Causes of macrocytic anaemia

A

BLOOMED B12 deficiency foLate deficiency Osteopetrosis O Myelodysplastic syndrome EtOH Diamond-blackan / Fanconi anaemia Drugs (MTX, chemo)

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16
Q

Causes of spur cells, bizarre red cells (poikilocytosis)

A

Vitamin E deficiency (neonates) Burns Hereditary pyropokilocytosis

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17
Q

Causes of target cells

A

Liver disease Thalassaemia

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18
Q

Post splenectomy changes

A

Target cells Spherocytes Acanthocytes Howell-Jolly bodies Nucleated RBC

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19
Q

Iron deficiency anaemia FBE, film + iron study results

A

FBE = low Hb, low MCV, elevated RDW, common to have thrombocytosis Film= cigar cells, target cells, tear drops, anisocytosis “pencil cells” Iron studies= low ferritin, low iron, high transferrin, low transferrin sat

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20
Q

Iron deficiency: supplementation + prevention

A

Supplementation - 2-6mg/kg/day of elemental iron - Usually reticulocyte response in 48-72hrs - Supplementation should produce a Hb rise of 1g/DL within 4 weeks Prevention - Encourage breast feeding - Iron fortified formula - Encourage vitamin C intake - Introduce iron rich foods from 6 months - Avoid unmodified cow’s milk until 12 months

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21
Q

Clinical consequences of iron deficiency

A

Most children are asymptomatic Pallor most important clinical sign- only apparent when Hb 70-80 Irritability, anorexia, lethargy + flow murmurs- when Hb falls to <50 Impaired lower scores on Bayley Scale of Infant Development Impaired short term memory + reduced attention in older children Poor growth PICA Exercise intolerance Breath holding spells

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22
Q

Results of iron studies, transferrin, ferritin, soluble transferring receptor in iron deficiency

A

Iron studies: decreased - Unreliable in diagnosis of iron deficiency - Good measure of compliance of supplements - Falls in acute illness Serum transferrin - Increased Transferrin saturation - Decreased Soluble transferrin receptor - Increased in iron def - NOT an acute phase reactant Ferritin - Acute phase reactant - Decreased Bone marrow - Iron stain: gold standard

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23
Q

Role of vitamin B 12

A

Cobalamin essential cofactor for: - Synthesis of methionine from homocyteine (requires 5-methyl-tetrahydrofolate) - Conversion of methylmalonyl CoA to succinyl CoA

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24
Q

Vitamin B12 absorbtion

A

Contained ONLY in animal products Binds to intrinsic factor produced by gastric antrum Gastrectomy affects IF production Absorbed in terminal ileum Transported bound to transcobalamin II which is required to enter cells

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25
Q

Risk factors for vitamin B12 deficiency

A

Maternal B12 deficiency - Pernicious anaemia - Vegetarian - Terminal ileal disease/ gastric bypass/ gastritis NEC Crohn’s disease Small bowel resection Blind loops/ intestinal infections Pancreatic deficiency

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26
Q

Clinical manifestations of vitamin B12 deficiency + test results

A

Neurological - Posterior columns affected - Pyramidal tracts - Peripheral neuropathy - Depression - Dementia Developmental delay or regression Hypersegmented neutrophils +/- teardrop cells Macrocytosis, anaemia Raised LDH, homocysteine, methylmolonic acid

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27
Q

What is holotranscobalamin?

A

Active B12 (measures the B12-TCII complex levels) Early marker of B12 deficiency

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28
Q

Intrinsic + extrinsic causes of haemolysis

A

Intrinsic - Abnormal Hb - Red cell enzyme deficiency - Red cell membrane disorder Extrinsic - DIC - Drug - Mechanical - Immune

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29
Q

Primary vs secondary autoimmune haemolysis

A

Primary - Warm: IgG (viral esp CMV, EBV). Spherocytosis. - Cold: IgM, complement (mycoplasma, EBV, syphilis). Agglutination. Secondary - SLE - Immunodeficiency - Infection - Drugs (penicillins, cephalosporins, quinidine, isoniazid, rifampicin) - Malignancy

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30
Q

Treatment of immune mediated haemolysis

A
  • Manage underlying disease - Infection associated is often self limiting - Minimise transfusion - Immunosuppression: more effective for IgG vs IgM - Splenectomy: curative in 60-80% - Rituxamab anti CD20 antibody
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31
Q

Causes of neutropenia

A

Post viral: most common Drugs Chronic benign neutropenia Cyclic neutropenia (FBE x 3 / week for 6 weeks) Severe congenital neutropenia: early onset + severe infections. May require high dose G-CSF Schwachman Diamond syndrome - Exocrine pancreatic insufficiency - Metaphyseal abnormalities - May progress to marrow aplasia - High risk of AML with G-CSF

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32
Q

What does PT test?

A

Extrinsic / common pathway II, V, VII, X

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33
Q

What does APTT test?

A

Intrinsic / common pathway VIII, IX, XI, XII

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34
Q

What are the stages of haematopoiesis in the fetus?

A

Mesoblastic (yolk sac + placenta) - Main source until ~ 6-8 weeks - Taken over by liver Hepatic - Starts 6-8 weeks Marrow + spleen - Increases in 2nd trimester

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35
Q

Does EPO cross the placenta?

A

NO! It is initially produced by monocytes + macrophages in the fetal liver + then shifts to the kidney post birth.

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36
Q

Where is the gene for beta Hb located?

A

Chromosome 11

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37
Q

Where is the gene for alpha Hb located?

A

Chromosome 16

38
Q

What does IL2 increase the production of?

A

NK/T cell/ B cell

39
Q

What does IL7/15 increase the production of?

A

T and NK development

40
Q

What is EDTA

A

Irreversible anti coagulant

41
Q

What is in the coags tube to prevent coagulation?

A

Sodium citrate a reversible coagulant

42
Q

Causes of spherocytes on a blood film

A

• Hereditary spherocytosis • Immune haemolytic anaemia • Post splenectomy • Liver disease

43
Q

Causes of schistocytes (helmet cells) on a blood film

A

• Microangiopathic haemolytic anaemia (eg. HUS/TTP, DIC) • Vasculitis • GN • Prosthetic heart valve

44
Q

Causes of target cells on a blood film

A

• Liver disease (macrocytic) • Thalassaemia (microcytic) • Hb SC • IDA • Asplenia

45
Q

Causes of teardrop cells on a blood film

A

• Myelofibrosis • Thalassaemia major • Megaloblastic anaemia

46
Q

Causes of heinz bodies (denatured + precipitated Hb)

A

• Oxidative stress • G6PD deficiency (post exposure to oxidant • Thalassaemia • Unstable Hb

47
Q

Causes of howell-jolly bodies

A

• Post-splenectomy • Hyposplenism (sickle cell) • Neonates • Megaloblastic anaemia

48
Q

Causes of sideroblasts (erythrocytes with Fe containing granules in the cytoplasm)

A

• Hereditary • Idiopathic • Drugs • Hypothyroidism

49
Q

What factors are in FFP

A

All factors

50
Q

What factors are in cryoprecipitate?

A

Fibrinogen, VIII/vWF, XIII Prepared by thawing FFP + recovering precipitate

51
Q

What factors are in prothrombinex?

A

2, 7, 9, 10

52
Q

What are the phases of RBC treatment?

A

Leukodepletion ( all products in Victoria automatically leukodepleted)

  • Reduces risk of non-haemolytic transfusion reactions, cytokine based reactions and infections such as CMV

Washing

  • Blood product washed in normal saline
  • Removes plasma proteins iii. Reduces risk of allergic reactions

Irradiation

  • Kills T -lymphocytes
  • Reduces risk of GVHD (AND risk of similar haplotypes reacting to each other  eg related donors)
  • Not required for acellular products (FFFP, cyro, albumin, globulins, clotting factors)

CMV negative

  • CMV transmission only associated with cellular blood products (RBC, WBC, platelets)
  • For CMV -ve transplant patients + neonates
53
Q
A
54
Q

Cause of febrile reactions with blood products

A
  • Recipient antibodies reacting with white cell antigens or white cell fragments in the blood
  • Cytokines which accumulate in the blood product during storage
55
Q

Cause of urticarial reactions with blood products

A

Caused by foreign plasma proteins

56
Q

Cause of severe allergic reactions with blood products

A

In some cases patients with IgA deficiency who have anti IgA antibodies can have these reaction

57
Q

Cause of citrate toxicity with blood products

A

Citrate is the anticoagulant used in blood products. Usually rapidly metabolised by the liver. If rapid administration of large quantities of blood may cause hypocalcaemia + hypomagnesaemia when citrate binds to Ca + Mg = myocardial depression + coagulopathy

Patients at high risk: liver dysfunction + neonates

58
Q

Mutation in polycythaemia rubra vera

A

Gain of function mutation of JAK2

59
Q

What is the role of B12

A
  1. Cofactor in the methylation of HOMOCYSTEINE —-> METHIONINE
  2. Cofactor in the convesion of MMA CoA —> succynyl COA

Deficiency in B12 = high homocysteine + high MMA

60
Q

What is B12 bound to when transported in the plasma

A

Transcobalamin II

61
Q

Where is the site of B12 absorption

A

Terminal ileum (absorption of B12 + IF via receptor mediated endocytosis)

Required chief cells in the stomach to release pepsinogen–> pepsin to break down + release B12 from proteins

Gastric antrum release intrinsic factor

B12 then binds to R proteins

R proteins are broken down by amylase/lipase/proteases

62
Q

What is pernicious anaemia

A

Antibody to intrinsic factor or parietal cells resulting in vitamin B 12 deficiency

63
Q

What is the 2nd most common cause of pancreatic insufficiency in children?

A

Schwachman Diamond syndrome

64
Q

Difference between direct + indirect coombs test

A

Direct detects antibodies/complement on the surface of RBC

Indirect detects antibodies in the serum

65
Q

Classification of haemolysis

  • Intrinsic/cellular
  • Extracellular
A

Intrinsic/cellular

  • Membrane
    • Hereditrary spherocytisis/ elliptocytosis/propoikilocytosis/PNH
  • Enzyme
    • G6PD deficiency
    • PK deficiency
  • Haemaglobinopathies
    • Sickle cell
    • Thalassaemia

Extracellular

  • Autoimmune
    • Warm (IgG)
    • Cold (IgM)
  • Fragmentation
    • DIC/TTP/HUS/aHUS
    • ECMO
    • Prosthetic heart valve
    • Burns
    • Hypersplenism
  • Plasma
    • Liver disease
    • Infection
66
Q

What is the most common inherited bleeding disorder?

A
  • Von Willebrand Disease
  • Most Autosomal Dominant: on short arm of chromosome 12
67
Q

What is Bernard-Soulier disease?

A

Severe congenital platelet disorder

Absence or severe deficiency of VWF receptor on platelet membrane

Inherited autosomal recessive

Features: thrombocytopaenia, giant platelets, prolonged bleeding time (> 20 mins)

68
Q

What is chronic ITP?

A

20% patients with acute ITP

Need to evaluate for associated disorders, especially autoimmune e.g. SLE, HIV, CVIS (common variable immunodeficiency syndrome, X-linked thrombocytopenia, Wiskott –Aldrich syndrome)

Treat with a splenectomy and/or medical therapy (IVIG, steroids, rituximab, IV anti D

69
Q

What is Wiskott-Aldrich syndrome?

A

Thrombocytopaenia with tiny platelets, eczema, recurrent infection due to immune deficiency

Inherited X linked

5% patients develop lymphoreticular malignancies

Splenectomy corrects thrombocytopaenia

Bone marrow transplant cures

70
Q

What causes target cells?

A

Thalassaemia, iron deficiency, post-splenectomy, autosplenectomy caused by sickle cell disease, liver disease

71
Q

What are bite cells?

A

Bite cells – suggest presence of Heinz bodies. Heinz bodies are membrane bound and bite cells are caused by their removal. Heinz bodies can only be seen on unstained or special stained films i.e. not on usual Wright stain

72
Q

Spherocytes are seen in hereditary spherocytosis but what is the main differential?

A

Autoimmune haemolytic anaemia

73
Q

What are the 3 types of von WIllebrand Factor?

A

Type 1: REDUCED vWF

Type 2: dysfunctional vWF

Type 3: absent vWF

74
Q

What is ristocetin co-factor?

A
  • Ristocetin is an antibiotic that is no longer in use clinically because it causes platelet agglutination.
  • If added to a sample that contains a normal amount of VWF, platelet aggregation will occur.
  • If there is reduced aggregation, this suggests reduced VWF activity.
  • If none occurs, this suggests severely reduced or absent VWF.
75
Q

What is in cyroprecipitate?

A
  • Fibrinogen
  • vWF
  • VIII
  • XIII
76
Q

What is the most common risk factor for renal vein thrombosis?

A
  • Birth asphyxia/ fetal distress
77
Q

What is the missense mutation that results in sickle cell disease?

A

Missense mutation GAG —-> GTG = substitution of valine for glutamic acid

78
Q

What is the mechanism of action of desmopressin (DDAVP) in the treatment of vWD

A

Desmopressin (dDAVP) is a synthetic analogue of antidiuretic hormone which retains antidiuretic activity but lacks vasopressor activity. It promotes the release of VWF from endothelial cell storage sites indirectly.

79
Q

What is thrombotic thrombocytopenia purpura?

A
  • Clinically similar to HUS
  • ADAMTS13-protease deficiency
    • ADAMTS13 protease usually cleaved vWF multimers. Without this cleavage vWF multimers circular + stimulate microvascular platelet thrombi
    • Results in microgangiopathic haemolytic anaemia + thrombocytopenia
  • Classical manifestations
    • Fever
    • Microangiopathic haemolytic anaemia
    • Thrombocytopenia
    • Abnormal renal function
    • CNS changes
  • Treatment
    • Plasmapheresis 80-95% effective
    • ADAMTS13 replacement (FFP)
    • Refractory
      • Rituximab
      • Corticosteroids
      • Splenectomy
80
Q

What are the investigations in VWD

A

Type 1: reduced vWF

  • Reduced VIII
  • Reduced ristocetin cofactor
  • Reduced vWF antigen

Type 2: dysfunctional vWF (qualitative)

  • Reduced ristocetin cofactor relative to vWf antigen

Type 3: complete deficiency of vWF

Ristocetin cofactor – functional assay

Von Willebrand factor antigen – quantitative assay

Factor VIII coagulant

PFA 100 – platelet function test

81
Q

What is the preferred blood product for correction of coagulation abnormalities?

A

Fresh frozen plasma is preferred over cryoprecipitate, coagulation factors, fibrinogen

82
Q

A term neonate born by vaginal delivery presents with petechia and purpura shortly after birth. A blood film shows large platelets which appear pale and hypogranulated. Which of the following is the most likely diagnosis?

  • Bernard Soulier syndrome
  • Glanzmann thrombasthenia
  • Gray platelet syndrome
  • Wiskott-Aldrich syndrome
A

Grey platelet syndrome is caused by absence of platelet alpha granules which leads to large platelets with a grey appearance. Babies present with symptoms shortly after birth.

  • Bernard-Soulier syndrome is caused by absence or deficiency of GPIb complex. It results in giant platelets.
  • Glanzmann thrombasthenia will have normal platelet count and size and appear normal on a blood film.
  • Wiskott-Aldrich syndrome associated
    • Thrombocytopenia with small platelets
    • Immunodeficiency
    • Malignancy risk
    • Eczema
83
Q

Thrombocytpenia + absent radi

A
  • Clinical manifestations
    • Severe thrombocytopenia
    • Bilateral absent radii (thumbs ALWAYS present)
    • Congenital heart disease 1/3
    • Intolerance to cow’s milk formula (present in ~50%)
  • Natural history = thrombocytopenia usually remits over first few years of life
  • Investigations= thrombocytopenia
84
Q

What is the pathophysiology of NAIT?

A
  • NAIT is caused when the father expresses a platelet antigen which the mother does not.
  • This antigen is recognised as foreign by the maternal immune system and leads to destruction of fetal platelets, which can lead to fetal and neonatal thrombocytopaenia.
  • This is in contrast to Neonatal Autoimmune Thrombocytopaenia where the mother will have thrombocytopaenia.
  • NAIT is often compared to Rh incompatibility by way of explanation. NAIT can occur in the first pregnancy.
  • There are over 20 platelet antigens but the most commonly implicated antigen in Caucasian women is Human Platelet Antigen 1a (HPA1a) which accounts for 85% of cases.
  • Only 3% of population do not express HPA1a so if the mother does not express HP1A, it is very likely that the father will.
85
Q

What is Heinz bodies comprised of?

A

Denatured Hb

In haemoglobinopathies, there is denaturation and insoluble precipitation of haemoglobin in red blood cells. There is the presence of an abnormality in the primary structure of haemoglobin. Heinz bodies are formed by the damage to haemoglobin. They attach to, and damage, the red cell membrane. There are present characteristically in the congenital Heinz body haemolytic anaemias, such as G6PD and alpha thalassaemia.

86
Q

What is Evan’s syndrome?

A
  • Haemolytic anaemia + ITP
87
Q

What is more common haemophilia A or B?

A

Haemophilia A

88
Q

Which of the following human platelet antigens (HPA) is most commonly implicated in FNAIT

A

HPA-1a.

  • Anti-HPA-1a antibodies account for 85% of FNAIT.
  • In Caucasian populations only approximately 2% of people are HPA-1a negative.
  • There are over 20 identified platelet antigens that are implicated in FNAIT, but <1% are caused by HPAs other than 1a, 5b and 4.
89
Q

What are the genetic causes of thrombocytopenia according to platelet size?

A

Small:

  • WAS
  • X linked thrombocytopaenia (XLT)

Normal:

  • Fanconi anaemia
  • Dyskeratosis congenital
  • Shwachman-Diamond syndrome
  • Congenital amegakaryocytic thrombocytopenia (CAMT)
  • Thrombocytopenia-absent radius (TAR) syndrome.

Large:

  • Bernard-Soulier syndrome
  • X linked thrombocytopaenia with dyserythropoiesis
90
Q

Which one of the following primary immunodeficiency disorders is most likely to be associated with anaphylaxis to blood products?

a) Ataxia-telangiectasia.
b) Common variable immunodeficiency.
c) IgG subclass deficiency.
d) Selective IgA deficiency.
e) X-linked agammaglobulinaemia.

A

Selective IgA deficiency.

Selective IgA deficiency is a low or absent IgA. Clinical features include:

Asymptomatic

Respiratory infections

Chronic diarrhoea

Increased type III hypersensitivity

Treatment is specific therapy for infections

Transfusion reactions are more common

91
Q

Which one of the following is the most common cause of familial thrombophilia (deep vein thrombosis and pulmonary emboli)?

a) Activated protein C resistance.
b) Antithrombin III deficiency.
c) Protein C deficiency.
d) Protein S deficiency.
e) Prothrombin gene mutation.

A

Activated protein C resistance

due to the factor V Leiden mutation is the most common genetic hypercoagulable condition in Caucasians.

An amino acid substitution in the gene coding for factor V results in the production of factor V Leiden, a factor V variant that is resistant to inactivation by activated protein C. About 20% of unselected consecutive Caucasian adults with DVT and 40-60% of Caucasian adults from families with unexplained thrombophilia have been identified with this mutation. Venous thrombosis has been reported in children both heterozygous and homozygous for this mutation. This mutation also predisposes to ischaemic stroke. Screening may be performed with an assay for activated protein C resistance. Confirmation is by genetic-molecular analysis.

Antiphospholipid antibodies are the most common acquired prothrombotic abnormality. Acquired activated protein C resistance may occur.

paediatrics (23 decks)

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