Thalassaemia Flashcards

1
Q

Define beta thalassaemia intermedia

A

Defined by RCOG as 7 or less transfusions per year or no transfusions per year

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define beta thalassaemia major

A

Homozygous beta thalassaemia trait - RCOG defines as more than 7 transfusions per year

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define haemoglobin H

A

3 alpha globin chains affected - haemoglobin consists of tetrameric beta and gamma chains - results in anaemia and splenomegaly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define haemoglobin Barts

A

4 alpha globin chains affected - tetrameric gamma chains - incompatible to life - leads to fetal hydrops or early neonatal death (hb has a high affinity for oxygen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Consequence of 1 defective alpha globin chain

A

Silent trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Consequence of 2 defective alpha globin chains

A

alpha thalassaemia trait - mild anaemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Consequence of beta thalassaemia major on pregnancy

A

Mild to moderate anaemia - folic acid 5mg recommended, iron replacement can be given if deficient, if symptomatic of anaemia, transfusion can be considered, risk of transmission to fetus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Pre-conception considerations of beta thal major and intermedia

A

Pituitary - hypogonadotrophic hypogonadism (ovulation induction with gonadotrophins, consider preimplantation genetic diagnosis)
Thyroid - low thyroid
Liver - iron, cirrhosis, gall stones
Pancreas - diabetes (test with fructosamine)
Heart - iron, cardiomegaly, heart failure, dysrhythmia
Blood - risk of VTE, infection risk (hep B/C), alloimmunisation
Infection - hepB/C, if splenectomy (risk of encapsulated infections)
Bone - osteoporosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is iron tissue deposition assessed in beta thal major and intermedia pre-conception

A

T2* cardiac MRI >20ms = low risk, <10ms high risk
T2* liver MRI or ferriscan - aim for 7mg/g dry weight pre conception, if >15mg/g high risk of cardiac iron - offer chelation 20-24 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is iron chelation managed pre-conception?

A

Aggressively.
Oral regimes should be stopped 3 month prior to conception (teratogenic)
IV desferrioxamine (short half life) can be used during ovulation induction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How often should beta thal intermedia and major be seen in pregnancy?

A

early scan 7-9 weeks, dating and anomaly scan, 4 weekly scans from 24 weeks
Monthly until 28 weeks then every 2 weeks in clinic
joint haem/mat med MDT involvement
Cardiac review at 28/40

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the implication for beta thal major/intermedia on developing fetus?

A

Alloantibodies secondary to multiple transfusions = risk of fetal and neonatal haemolysis
Fetal growth restriction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the implications for beta thal major/intermedia on pregnant woman?

A

Co-morbidities - hypothyroid, diabetes
Cardiac decompensation and dysrhythmia in labour
Iron deposition as no longer using chelating agents
VTE risk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How should VTE risk be managed in beta thal major and intermedia?

A

Splenectomy or plt >600 = aspirin
Splenectomy AND plt >600 = aspirin and LMWH
Antenatal admission = LMWH
Postpartum LMWH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How should patients with beta thal major and intermedia be assessed for diabetes?

A

Hba1c is inaccurate - serum fructosamine should be used

Aim for <300 pre conception

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the intrapartum management of beta thal major and intermedia?

A
If alloantibodies - crossmatch 2 units
Mode and timing is obstetric decision
Beta thal major - desforoxamine, 2g 24 hour infusion in labour 
Continuous CTG monitoring
Active management of 3rd stage
17
Q

What is the postpartum management of beta thal major and intermedia?

A

Encourage to breast feed
Can restart oral chelating agents
LMWH prophylaxis

18
Q

What is the indication for transfusion in pregnancy for beta thal major and intermedia?

A

FGR or worsening maternal anaemia (e.g. <100)

If <80 at 37-38 weeks - transfuse, if >80 and not previously transfused at 36 weeks - don’t transfuse

19
Q

What is the indication for iron chelation in pregnancy for beta thal major and intermedia?

A

iron chelation is done with low dose desferioxamine at 20-24 weeks for patients with either evidence of high risk cardiac decompensation T2*MRI <10ms, hepatic iron overload >15mg/g dry weight

20
Q

What is the frequency of alloimmunisation in beta thal major patients?

A

16.5%

21
Q

What is the frequency of alloimmnisation in sickle cell disease patients?

A

18-36%