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Peads > Haematology > Flashcards

Haematology Flashcards

1
Q

Explain the normal types of haemoglobin in adult?

A

HbA (a2b2) 90%
HbA2 (a2d2) 3%
HbF (a2g2) 1%
Neonates has majority HbF but some HbA (25%)

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2
Q

What are the main causes of haemolytic anaemia in the newborn?

A

-Blood group incompatibility (Rh or ABO)
-Red cell membrane disorders e.g. hereditary spherocytosis
-Red cell enzyme disorders (G6PD deficiency)
Abnormal haemoglobin (thalassaemia major)

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3
Q

What is beta-thalassaemia?
How is it inherited?
Who normally gets it?

A
  • Affects the PRODUCTION of haemoglobin (reduced or none)
  • Globin part not heme part (like IDA and Achronic disease)
  • AUTOSOMAL RESSESIVE MUTATION
  • Typically people on the Indian Sub-Continent, Mediterranean and the middle east
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4
Q

What is the consequence of beta-thalassaemia on the Hb conformity?

A

Beta-thalassaemia

  • reduced HbA
  • increased HbF (doesn’t contain beta chain)
  • increased HbA2 (doesn’t contain beta chain)

-Severity of the disease depends on how much HbF resides

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5
Q

What will the clinical presentation be of beta-thalassaemia major?

A
  • Extra medullary haematopoiesis leads to hepatosplenomegaly
  • Classic ‘rodent’ face- overaction of the bone marrow leads to classical bossing of skull and forehead and maxillary overgrowth and malocclusion of teeth
  • Neonatal jaundice (heamolysis)
  • Anaemia signs (pallor, heart murmurs, FTT
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6
Q

What is beta thaleaseamia B Major (homozygous) ?

A
  • both beta chains are effected (all alpha)
  • HbA cannot be produced at all so blood transfusion are necessary for survival (to prevent Extramedullary hemopoiesis and bone deformities)
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7
Q

Explain the genetics of alpha thalesemia

A 
Alpha thalassemia (genetic DELETION)
• Inherit 1 alpha gene-asymptomatic 
•  Inherit 2 alpha genes-trait 
•  Inherit 3 alpha genes-marked anemia
•  Inherit all 4 alpha genes-Hb BARTS 
      -death in utero>hydrops fetalis
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8
Q

What is the management for thalesmias?

A

They will need intervention if severe:

  • regular blood transfusions with iron chelation (to prevent heamatomachrosis)
  • folate supplementation (heamolysis causes deficiency)
  • splenectomy may be indicated to prevent heamolysis of RBC
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9
Q
  • How common is sickle cell?
  • Who is most likely to get sickle cell disease?
  • How can we diagnose?
A

Sickle Cell anaemia

  • the most common inherited genetic condition in UK
  • most common in afro-Caribbean population
  • diagnosed by blood smear
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10
Q

Describe the pathophysiology of sickle cell anaemia

How do these RBC cause disease?

A
  • AUTOSOMAL RECESSIVE
  • There is a point mutation in codon six on the beta chain of haemoglobinA meaning there is an amino acid swap (missence glut acid>valine)

RBC cause disease due to:

1) Heamolysis
2) Vasoocclusion

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11
Q

What triggers an acute sickle cell episode?

A
  • Cold, low oxygen and dehydration (think about being on a mountain)
  • Infection
  • Stress
  • acidosis also reduces affinity for Hb for oxygen
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12
Q

Explain the 4 types of sickle cell?

A

1/ SICKLE CELL ANAEMIA (Homozygous)

  • HbSS (virtually all their Hb is HbS)
  • They have small amount of HbF and NO HbA
  • Most severe

2/ HbSC DISEASE (combined heterozygous)

  • Affected children inherit HbS from one parent and HbC from another (HbC is a different point mutation on the beta-globin chain).
  • They also have no HbA

3/ SICKLE TRAIT:

  • Single copy of HbS (inheritance of Hbs from one parent but normal HbA genes from the other)
  • Asymptomatic carriers
  • Small amounts of HbF

4/ SICKLE BETA THALASSEMIA

  • HbS/beta thalaseamia
  • affect structure AND production
  • Affected children inherit HbS from one parent and beta-thalassemia from another.
  • They have no normal B-globin genes and so most patients can make no HbS
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13
Q

Long term treatment of sickle cell disease?

A

PREVENTION
1) AVOID TRIGGERS (dehydration, altitude)

2) LONG TERM ANTIBIOTICS
- Daily phenoxypenecillin (Pen v)

3) FULLY IMMUNISED
- autosplenectomy
- especially encapsulated organisms (Salmonella, HiB, strep pneumonia)

4) HYDROXYUREA (Hydroxycarbamide)
- increases fatal haemoglobin

COMPLICATIONS

  • Once daily folic acid (increased demand for folic acid due to increased hemolytic anemia)
  • Bone marrow transplant/gene therapy as well
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14
Q

How should we manage a sickle cell crisis?

A
  • Management with OXYGEN AND FLUIDS improves the following triggers:
    ○ Hypoxia
    ○ Acidosis
    ○ Dehyration
  • OPIODS-pain releif
  • ANTIBIOTICS (treat underlying bacterial infection from acute chest syndrome)
    -BLOOD TRANFUSION in ACS, stroke or priapism
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15
Q

Whats the function of factor VIII (8) and factor IX (9)?

A

8 and 9 combine to activate factor 10

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16
Q

What are the most commonly inherited coagulation disorders? How are they inherited?

A

Haemophilias A and B

They are X-linked (passed down to boys through the maternal line)

17
Q

What is haemophilia B and how will it present?

A
  • Factor IX deficiency

- usually presents as bleeding into joints and muscles that will lead to crippling arthritis

18
Q

What is haemophilia A and how will it present?

A
  • Heamophillia A is Factor VIII deficiency
  • Will usually only present when they start to walk/crawl -covered in bruises (A first then B)

Other presentations might include intra-cranial bleeding in the neonatal period, excessive bleeding after circumcision, heel prick test or venipuncture

19
Q

How should we manage acute haemophilia bleed?

A

Acute bleed
• Treatment with RECOMBINANT clotting factors given IV
- FVIII (8) for haemophilia A
- FIX (9) for haemophilia B

  • Tranexamic acid (orally) can reduce bleeds
  • Physio for any bleed related arthritis
20
Q

Can we treat haemophilia A prophylactically?

A

YES - definitely with haemophilia A (treat with prophylactic FVIII that is given through a portocath)

DESMOPRESSIN can also be given to stimulate endogenous release of FVIII and vWF

Give Emicizumab subcut

21
Q

Investigations of haemophilia?

A

INVESTIGATIONS
Investigations of haemophilia
-FBC (low heamatocrit and Hb if recent bleed)
-Prothombin time (extrinsic and common), fibrinogen levels and vW factor should be normal
-Activated partial thromboplastin time (APTT) should be prolonged (intrinsic (8,9) and common)
-Then look for specific factors
-Genetic mutation tests
-LFTs

22
Q

What should you council patients about haemophilia?

A
  • ***all IM injections, aspirin and NSAIDs should be avoided in patients with haemophilias
  • check before vaccines-give subcut instead
  • Avoid contact sports
23
Q

What are the 2 types of heamaglobinopathies?

A 
Heamaglobin variants (affect STRUCTURE)
-HbS
-HbC 
-HbE
Thalaseamias (affect PRODUCTION)

can get both

24
Q

Symptoms of sickle cell aneamia?

A 
Symptoms of sickle cell aneamia
-Infection 
-Severe anemia (SOB, palpatations)
-Vaso-occlusive phenominom 
• acute pain episodes 
• stroke (heamorragic and ischemic) 
• acute chest syndrome 
• AKI (papillary necrosis) 
•  Avascular necrosis 
• priapsim (4+ hours is med emergency)
25
Q

What is acute chest syndrome?

What are symptoms?

A

Acute chest syndrome

  • Complication of sickle cell anemia
  • Fever with (or without) respiratory symptoms
  • SOB, chest pain, pulmonary infiltrates, low pO2
26
Q

What are investigations (and results) of acute chest syndrome?

A
  • Chest X ray (pulmonary infiltrates)

- ABG (hypoxia)

27
Q

Treatment of acute chest syndrome?

A
  • IV AB, oxygen, hydration

- exchange transfusion can be used to treat acute chest syndrome in hypoxic patient

28
Q

What is the most common haematological abnormality in the newborn?

A

Haemolysis of the newborn

Either due to antibody destroying fetal blood cells or an intrinsic abnormality in the baby’s blood cells themselves

29
Q

What type of anaemia does thalassaemia cause?

A

Thalaseamias cause microcytic anaemia (if a suspicion IDA doesn’t respond to treatment think thalasseamia)

30
Q

What are the causes of microcytic aneamia?

A

1) Iron deficiency anaemia
2) Thalaseamias
3) Anaemia of chronic disease (normocytic first)
4) Sideroblastic anaemia

Peads (29 decks)

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