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Haematological Disorders Flashcards

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1
Q

Where does haematopoiesis take place in Utero? Post natal?

A

Liver, spleen

Bone marrow

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2
Q

How does Hb and haematocrit compare in newborn to normal? Why? How does this change?

A

High (14-20g/dL) due to low oxygen tension in Utero.

Value declines over 2-3 months to give a physiological anaemia (9g/dL)

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3
Q

In preterm infants does the physiological anaemia take longer or shorter to decline?

A

It’s faster (7/52)

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4
Q

What happens during the physiological anaemia of newborn

A

Erythroid hyperplasia (increased growth of RBCs) in the marrow & a change from fetal (HbF) to adult (HbA) haemoglobin

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5
Q

What is anaemia

A

Decrease of circulating haemoglobin

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6
Q

Most common cause of anaemia

A

Dietary iron deficiency

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7
Q

How is anaemia Classified

A

Colour - mono/hypochromic

Size - micro/normo/macrocytic

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8
Q

Causes of microcytic hypochromic anaemia

A

Iron deficiency
Chronic inflammation
Thalassaemia

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9
Q

Causes of intrinsic RBC defects

A

Spherocytosis, sickle cell disease, G6PD deficiency

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10
Q

Causes of extrinsic RBC defects

A

Rh incompatibility (immune mediated)
Haemorrhage eg. Menstruation, meckels diverticulum
Hypoproduction disorders - renal disease (RBCs), marrow aplasia, leukaemia (pancytopenia)

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11
Q

What causes macrocytic anaemia

A

Bone marrow megaloblastic - b12/folate deficiency

Not megaloblastic - hypothyroidism, fanconi anaemia

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12
Q

Describe anaemia in iron deficiency

A

Hypochromic, microcytic

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13
Q

How does the fetus receive iron? How long does it have reserves for after birth ?

A

Placenta

4/12

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14
Q

Dietary sources of iron ? How to increase absorption ? What decreases absorption ?

A

Red meat, dark green veg, bread (10% absorbed)

Increased by ascorbic acid (vit c)

Decreased by tannins (eg. Tea)

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15
Q

Causes of iron deficiency

A

Nutritional - preterm infants, poor diet (associated with low socioeconomic status)
Menstruation, recurrent epistaxis (nose bleed)
Malabsorption

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16
Q

Features of iron deficiency ? O/e?

A

Mild - asymtomatic
Irritability, lethargy, fatigue, anorexia
O/e - pallor of skin, conjunctiva, other mucous membranes

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17
Q

Why do preterm infants get iron deficiency

A

Breast milk / cows milk low in iron

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18
Q

Diagnosis of iron deficiency anaemia

A

Blood count & film + ferritin

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19
Q

Management of iron deficient anaemia

A

Oral - 6mg/kg/day PO

This equals - 30mg/kg/day ferrous sulphate for 3-6 months

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20
Q

What are the DDs of microcytic hypochromic anaemia

A

Iron deficiency
Chronic disease
Thalassaemia
Sideroblastic anaemia

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21
Q

Where is the defect in thalassaemia

A

Globin synthesis

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22
Q

Two types of thalassaemia

A

Alpha and beta in their respective globin chains

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23
Q

Pathology of thalassaemia ? 2 ways it causes damage?

A

Mutations lead to reduction/ absence of globin chains -> excess globin chants of the other subtype remain unpaired -> join to form insoluble tetramers that precipitate membrane damage:
1 - cell death within the bone marrow (ineffective erythropoesis)
2- premature removal by the spleen (resulting in haemolytic anaemia)

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24
Q

Who is likely to get b-thalassaemia ? What are the two types?

A

Mediterranean & middle eastern
B-Thalassaemia major - homozygous
B-T-minor - heterozygous (“b-thalassaemia trait)

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25
What happens in b-T-Major
Usually complete absence of B-globin chains -> HbA cannot be synthesised
26
Features of b-T-MAJOR? What happens if left untreated?
Usually present at 6/12 with *severe haemolytic anaemia, jaundice, failure to thrive and hepatosplenomegaly Bone marrow hyperplasia -> maxillary hyper trophy, skull bossing*
27
Diagnosis of b-t-M
Hb electrophoresis - decreased HbA and increased HbF
28
Treatment of B-T-M? Side effects?
*Regular blood transfusions* aiming to keep the Hb >10g/dL | Iron deposition in heart, skin, liver, pancreas, gonads
29
Prognosis of B-T-M
Many die from congestive heart failure due to cardiomyopathy in their 2nd/3rd decade
30
What can B-T-m be misdiagnosed as? What is the type of anaemia ? Usual symptoms?
Iron deficiency anaemia Hypochromic, microcytic anaemia Asymtomatic
31
Diagnosis of B-T-m
Increased HbA2 (50% have mild increase in HbF)
32
How bad is A-T
Manifestations and severity depend on number of genes deleted. Eg a-T-M -> death in Utero, hydrops fetalis
33
What causes haemolytic anaemias? What are they characterised by (4things)?
When RBC lifespan is under 120 days | Anaemia, reticulocytosis, increased erythropoesis in bone marrow, unconjugated hyperbilirubinaemia
34
Egs of haemolytic anaemias
Hereditary sphereocytosis, sickle cell, G6PD deficiency, pyruvate kinase deficiency
35
What is hereditary sphereocytosis ? Genetics?
*AD* caused by abnormalities in *spectrin* (major RBC membrane support protein) (25% cases are sporadic) Cells are spherical and lifespan reduced by early destruction by spleen
36
Features of spherocytosis
*Severe anaemia aged 1-3 months with unconjugated *jaundice & splenomegally
37
Complications of spherocytosis ? Why?
* Aplastic crisis* secondary to parvovirus B19 (Vth disease, "slapped-cheek") * gallstones* - due to increased bilirubin excretion
38
Diagnosis of spherocytosis ?
Spherocytes on blood film. Confirmed by *osmostic fragility test*
39
How does the osmotic fragility test work?
Spherocytes already have maximum SA:volume ratio therefore they rupture more easily than biconcave RBCs in hypotonic solution
40
Management of spherocytosis ? What's needed for life after?
Splenectomy - transfusion dependency, uncompensated haemolysis Prophylactic penicillin for life following splenectomy
41
Pathophysiology of sickle cell ?
Homozygous mutation of B-globin gene - HbS aggregates into long polymers that distort the RBCs into a sickle shape. Point mutation which *substitutes glutamine for valine at codon 6* in B-globin.
42
Who gets sickle cell
Black Afro-Caribbean, middle eastern
43
Why does having sickle cells cause issue
Reduced life span | Get trapped in microvasculature
44
Features of sickle cell? Neonate? Presentation
Synthesis of HbF offers protection until *4-6 months* -> *progressive anaemia with jaundice & splenomegaly* then develops Present with episode of *dactylitis* or overwhelming infection
45
What commonly triggers the vaso-occlusive crises in sickle cell
*Infection, dehydration, chilling* or vascular stasis
46
Features of a vaso-occlusive crisis ? Where are they uncommon?
Most are painful, particularly in *long bones & spine* | Cerebral and pulmonary vasculature
47
What happens if there is a vasoocclusive crisis in pulmonary vasculature?
'*acute chest syndrome' - fever, Crepitations, chest pain & shadowing on chest X-ray*
48
What happens to the spleen in sickle cell disease
Infancy - splenomegaly | But recurrent infarction -> *autosplenectomy* spleen regresses and is impalpable by 5 years
49
What are you at risk of if your spleen regresses?
Hypo function -> risk of *overwhelming infection with capsulated organisms* eg. H. Influenzae, S. Pneumonae
50
What are the long term consequences of sickle cell?
``` Myocardial damage and HF Gall stones Aseptic necrosis of long bones Renal papillary necrosis Leg ulcers ```
51
Management of sickle cell
Prophylaxis - *penicillin* though childhood, pneumococcus & meningococcus immunisations (+standard Hib) Daily folic acid - meet demands of increased RBC breakdown
52
Management of vasocclusive crisis
Supportive - analgesia (opioids), oxygen, hydration with IV fluids
53
When is an exchange transfusion indicated in sickle cell
Acute chest syndrome, stroke or priapism
54
Cure for sickle cell?
Bone marrow transplant - must come from HLA-identical sibling Hydroxyurea which increases HbF production is being trialled
55
What is the genotype of sickle cell carrier - Hb...? What are their symptoms ?
HbAS | Asymtomatic unless subjected to hypoxic stress (eg. General anaesthetic)
56
What happens if you get HbS & HbC from parents?
Get no HbA, but are mostly asymtomatic | Need to look out for retinopathy in adolescence
57
What happens if you get HbS and B-thalassaemia from parents?
Similar presentation to sickle cell
58
2 RBC enzyme deficiencies
Glucose-6-phosphate dehydrogenase | Pyruvate kinase
59
Genetics of g6pd ? Who gets it? What does g6pd usually do?
X linked recessive Afro-c, mid-east, Mediterranean, oriental *prevents oxidative damage to RBC*
60
Features of g6pd deficiency
Neonatal jaundice - usually in first 3/7 of life Acute haemolysis - induced by *infection, oxidant drugs & fava beans* *fever, malaise, passage of dark urine*
61
Egs of oxidant drugs
Antimalarials, some Abx eg Ciproflaxacin, quinolones
62
Gene transfer of pyruvate kinase deficiency? What can happen ?
``` AR Infection induced (parvovirus B19) haemolysis ```
63
Deficiency / disorder of what 3 things could lead to bleeding disorders
Blood vessels Platelets (thrombocytes) Coagulation factors
64
Clinical features of bleeding disorders
Petichae / purpura Prolonged bleeding after dental extraction, surgery or trauma Recurrent bleeding into muscles or joints
65
Eg of disorders of blood vessels
*Ehlers-Donlos syndrome* | Henoch - schonlein purpura
66
What is Ehlers-Donlos syndrome ? What are the features
``` Inherited disorder (many types but vasuclar type is type IV) Capillary fragility & hereditary haemorrhagic telangiectasia ```
67
What platelet count for thrombocytopenia ? When does purpura occur?
<150x10^9 /L | <20
68
What is the commonest form of thrombocytopenia ? Incidence? pathology? Where does destruction occur? What else accompanies low platelet count?
Immune ('idiopathic') thrombocytopenia (ITP) 4/100,000/Year *Immune mediated destruction of circulating platelets due to anti platelet autoantibodies* Spleen *compensatory increase in megakaryocytes in marrow*
69
Presentation of thrombocytopenia
Usually between 2-10 years, usually *1-2 weeks post viral infection* *purpura and superficial bruising, mucosal bleeding (epistaxis / from gums after brushing teeth)* Profuse mucosal bleeding is rare as is intracranial haemorrhage
70
What are the differentials of ITP ?* what are features of other
Acute leukaemia (?lymphadenopathy ?hepatospenomegaly ) Aplastic anaemia Non accidental injury
71
Investigations of ITP ?
FBC - decreased platelets ( all else normal) | Bone marrow - if abnormal features to exclude leukaemia / aplastic anaemia)
72
Prognosis of ITP
In most children it is *acute, benign & self limiting* within 6-8 weeks with no treatment
73
When do you treat ITP ? With what?
``` Major bleed (IC / GI), persistent minor bleed Oral prednisolone or IV immunoglobin ```
74
What do you always need to do if treating ITP with steroids
Examine bone marrow as treatment can mask features of acute leukaemia & aplastic anaemia
75
Egs of coagulation disorders
Haemophilia A / B | Von Willebrand disease
76
Haemophilia A is deficiency in what? Genetics? How common?
Factor VIII X-linked recessive (1/3 new mutations) 1:5000
77
What are the components of factor VIII
VIII:C - (deficient in Haemophilia A) A low molecular weight unit VIII: R - 'Von Willebrand factor' - high molecular weight unit
78
What determined the severity of haemophilia A
The levels of factor VIII
79
Levels of factor VIII and effect in haemophilia A?
1% Severe (spontaneous joint/muscle bleeds) 1-5% moderate (bleeds after mild trauma) 5-40% mild (increased bleeding after surgery/ dental work)
80
What is the characteristic feature of haem A ? How does it usually present and at what age? Later in life?
*spontaneous or traumatic bleeding* Present at 12 months when start to crawl & walk (&fall) with easy brusing / bleeding Later - recurrent soft tissue/muscle/joint bleeding is main problem *haemarthroses - cause pain & swelling of affected joint*
81
Management of haem A?
Recombinant factor VIII by IV infusion to avoid chronic joint damage / arthritis
82
Deficiency in haem b? Genetics? Other name? Features? Management?
Factor IX X-Linked recessive ( less common) Similar features to A Recombinant factor IX
83
Bon Willebrand deficiency? What does this factor usually do? How common is this? Genetics? Management?
``` VW factor (factor VIII:R) Acts as a carrier protein for VIII:C & facilitates platelet adhesion 1% of population AD - with variable penetrance Desmopressin (DDAVP) ```
84
What should be avoided in VW disease?
IM injections, aspirin & NSAIDs
85
What happens in disseminated intravascular coagulation?
Coagulation pathway activation leads to diffuse fibrin deposition in the microvasculature & consumption of coagulation factors & platelets
86
Causes of DIC with egs.
Damage to vascular endothelium (eg. Sepsis / renal disease) Thromboplastic substances in circulation (eg. Acute leukaemia) Impaired clearance of activated clotting factors (eg liver disease)
87
Features of DIC
Diffuse bleeding diathesis (eg. Arising from venopuncture site); bleeding from lungs; bleeding from GI tract
88
Investigations and diagnosis of DIC
Prolonged prothrombin time (INR), activated partial thromboplastin time (APTT) & thrombin time (TT). Thrombocytopenia, increased D-diners and decreased fibrinogen
89
Treatment of DIC
Supportive and replacement of platelets & fresh frozen plasma
90
What other thrombotic disorders are there?
Factor V Leiden - abnormal fV protein that is resistant to protein C Protein C deficiency - (usually inactivates the activated forms of factors V& VIII and stimulated fibrinolysis) Protein S deficiency - co factor to protein C Antithrombin III deficiency

Peadiatrics (14 decks)

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