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Haemotology > Thalassemia > Flashcards

Thalassemia Flashcards

1
Q

Inheritance of thalassemia

A

Autosomal recessive

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2
Q

Affect of thalassemias on RBC

A

Anaemia
Microcytic RBC

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3
Q

Why do thalassemias cause anaemia

A

Shsortened RBC half life and bone marrow cant keep up with RBC production

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4
Q

What can increased RBC destruction cause

A

Jaundice
Increased likelihood for gallstones

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5
Q

When does alpha thalassemia start affecting patient

A

First trimester of pregnancy to adulthood as require alpha chains from foetus for Hb

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6
Q

When does beta thalassemia start affecting patient

A

After 4-5 months old - when beta chains start being importnat for Hb

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7
Q

What genetic abnormality causes beta thalassemia major

A

2 abnormal genes

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8
Q

Situations that can cause beta thalassemia intermedia

A

2 mildly abnormal genese
One very abnormal gene

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9
Q

What is dominant negative beta thalassemia

A

Where the one abnormal beta chain protein inhibits function of the normal protein

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10
Q

What beta thalassemia diseases require regular transfusions

A

Major = lifelong
Intermediate = regular potentiall required

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11
Q

What will one gene abnormality in beta chain cause?

A

beta thalassemia trait - asymtpomatic

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12
Q

What is the normal number of genes for encoding alpha chains

A

4

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13
Q

What does alpha thalassemia severity depend on

A

how many genes lost

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14
Q

What does 0 working alpha chains cause

A

Hb barts or hydrops fetalis - incompatible with life

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15
Q

How can try and prevent alpha thalassemia complete causing hydrops fetalis

A

Intrauterine transfusion and post natal bone marrow transplant

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16
Q

What does 3 working alpha genes cause

A

Asymptomatic, no anaemia, ay have slight miscrocytic RBC

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17
Q

What causes HbH and what are the clinical features

A

1 working alpha gene
Microcytosis Marked anaemia
Surprisingly well often

18
Q

What does unbalaced/ineffective Hb stimulate

A

Production of more Hb
Iron absorpiton (causes Fe overlaod)

19
Q

What does overporduction of Hb cause

A

Extramedullay haemotopoeisis
Bony deformity

20
Q

What can bony deformity in thalassemia present as

A

‘hair on end’ skull radiograph
Thalassemic face - deformity
Risk of fractures

21
Q

Treatment for beta thalassemia symptomatic or physiological

A

1st line - blood transfusions - ALL beta majors
Hydroxycarbamide - beta intermedia
Lutacerpt- decrease transfusion burden in some
Bone marrow transplant
Gene therapy
Genetic counselling - select unaffected embryos
Iron chelation to mitigate overload effects

22
Q

Complications of thalassemia

A

Iron overlaod from regular blood transfusions

23
Q

iron overload complications (from transfusions)

A

Endocrine - diabetes, stunted grwoth
Cardiac arrhythmias
Hepatic toxiity - cirrhosis, HCC

24
Q

Summary of hereditary spherocytosis

A
  • Often asymptomatic until increased O2 requirement
  • Treatment supportive
  • Folate replacement
  • Increased thrombotic risk
  • Increased risk of pulmonary HPTN
25
Q

G6PD deficinecy summary

A
  • Acute haemolysis when exposed to oxidants
  • Classic = broad beans 9fava beans), many other drugs also cause haemolysis
    • Antimalarials, antibiotics, chemotherapy
      X linked (can affect females if both chromosomes affected)
26
Q

What do all inherited anaemias increase risk to?

A
  • Specific risk from parvovirus B19 infection
  • Can cause temporary halt of RBC production -. profound anaemia
27
Q

What diseases cause iron overload due to transfusions but canot venesect as transfusion dependent eg may need iron chelation

A

, beta thalassemia major, severe beta thalassemia intermedia, sickle cell anemia, myelodysplasia, aplastic anemia

28
Q

Meds for thalassemia iron chelation

A

Deferixamine
Deferrasirox

29
Q

HBH globin cells present

A

moderate anaemia and microcytic, hypochromic red cells anisopoikilocytosis (red blood cells of varying and abnormal sizes and shapes), teardrop cells and basophilic stippling.

30
Q

Test for thalassemia

A

haemoglobin electrophoresis

31
Q

When give folic acid supplementation

A

High turnover of RBC eg haemolysis

32
Q

Haemoglobin electrophoresis in alphA HbH disease

A

Reduced HbA
Increased HbH = large amounts

33
Q

Haemoglobin electrophoresis in beta thalassemia trait

A

raised level of haemoglobin A2 (HbA2)

34
Q

Features of beta thalassemia major

A

Severe anaemia
Bony expainsion
Hepatosplenomegaly and jaundice

35
Q

What surgery can reduce blood requirement in beta thalassemia major

A

Splenectomy

36
Q

Investigation results in beta thalassemia majro

A

Full blood count: microcytic anaemia
Liver function tests: isolated hyperbilirubinemia
Ferritin or iron studies: normal iron levels, differentiating thalassaemia from iron deficiency anaemia
Blood film: hypochromic, microcytic anaemia, nucleated red blood cells, target cells, polychromasia (reticulocytes) and basophilic stippling
Haemoglobin electrophoresis or HPLC: absence of HbA, both HbF and HbA2 are elevated

37
Q

Screening for thalassemia

A

Pregnant women are offered a blood test before they reach 10 weeks gestation to identify carriers of thalassaemia.
If mum is carrier father offered testing. If both parents -> chorionic villus sampling or amniocentesis->thalassaemia status.
Testing for thalassaemia is also included in the newborn blood spot for babies 5-8 days old.

38
Q

What infections does splenectomy increase the risk of

A

pneumococcal, Haemophilus and meningococcal infection

39
Q

Infections seen in iron overlaod

A

klebsiella, yersinia and fungal infection

40
Q

Blood transfusion complications if regular

A

Infection
Osteoporosis
Transfusion reactions
Alloimmunisation - transfused patient develops antibodies against red cell antigens, difficulties crossmatching and trasnfusion reactions
Endocrine complications: due to iron overload, patients can develop delayed sexual maturation, infertility, thyroid dysfunction and parathyroid dysfunction.
Cardiovascular complications: iron overload increase the risk of arrhythmias and heart failure due to iron-induced cardiomyopathy.
Thrombosis: thalassaemia increases the risk of thrombosis.
Other complications: gallstones, leg ulcers, gout and skin bronzing due to iron overload

Haemotology (19 decks)

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