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Year 4 Paediatrics > Haematology > Flashcards

Haematology Flashcards

1
Q

How many protein subunits form haemoglobin?

A

Four, made of two pairs of subunits

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2
Q

HbF - subunits

A

Two alpha
Two gamma

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3
Q

HbA - subunits

A

Two alpha
Two beta

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4
Q

Differences between fetal and adult haemoglobin

A

SUBUNITS: Adult x2 alpha and x2 beta sub units, fetal x2 alpha x2 gama subunits

O2 exhange: In adults Hb binds to O2 in lungs, in the fetus, HbF picks up O2 in the placenta from mothers HbA

AFFINITY: HbF has greater affinity - O2 binds more easily and is released less easily
Partial pressure of O2 required: Adult haemoglobin requires a higher partial pressure of oxygen for the molecule to fill with oxygen compared with fetal haemoglobin.

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5
Q

At what gestation does production of HbF decrease and HbA increase?

A

32-36 weeks.

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6
Q

Eventually, red blood cells contain entirely HbA. At what age is there only very little HbF profuced?

A

6 weeks

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7
Q

Why does sickle cell disease not affect fetal haemoglobin?

A

In sickle cell disease, a genetic abnormality coding for the beta subunit is responsible for causing the sickle shape of the red blood cells.

Fetal haemoglobin does not lead to sickling of red blood cells because there is no beta subunit in the structure.

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8
Q

What is the role of hydroxycarbamide in sickle cell anaemia?

A

Hydroxycarbamide can be used to increase the production of fetal haemoglobin (HbF) in patients with sickle cell anaemia.

This has a protective effect against sickle cell crises and acute chest syndrome.

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9
Q

How does the normal range of Hb vary as children get older?

A

Decreases

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10
Q

What causes most cases of anaemia in infancy?

A

Physiologic anaemia of infancy

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11
Q

Causes of anaemia in infancy?

A

Physiologic anaemia of infancy
Anaemia of prematurity
Blood loss
Haemolysis (haemolytic disease of the newborn, hereditary spherocytosis, G6PD deficiency)
Twin-twin transfusion, where blood is unequally distributed between twins that share a placenta

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12
Q

Causes of haemolysis in the neonate

A

Haemolytic disease of the newborn (ABO or rhesus incompatibility)
Hereditary spherocytosis
G6PD deficiency

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13
Q

At what age does physiologic anaemia of infancy occur?

A

There is a normal dip in haemoglobin around six to nine weeks of age in healthy term babies.

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14
Q

Why does physiologic anaemia of infancy occur?

A

High oxygen delivery to the tissues caused by the high haemoglobin levels at birth cause negative feedback.

Production of erythropoietin by the kidneys is suppressed and subsequently there is reduced production of haemoglobin by the bone marrow.

The high oxygen results in lower haemoglobin production.

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15
Q

Premature neonates are much more likely to become significantly anaemic during the first few weeks of life compared with term infants. The more premature the infant, the more likely they are to require one or more transfusions for anaemia.

For what reasons do premature neonates become anaemic?

A

Less time in utero receiving iron from the mother

Red blood cell creation cannot keep up with the rapid growth in the first few weeks

Reduced erythropoietin levels

Blood tests remove a significant portion of their circulating volume

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16
Q

When is anaemia of prematurity more likely to occur?

A

The more premature the neonate is

Significant number of blood test

Unwell at birth, particularly with neonatal sepsis

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17
Q

Why Haemolytic Disease of the Newborn occur?

A

It is caused by incompatibility between the rhesus antigens on the surface of the red blood cells of the mother and fetus.

Rhesus D negative mother becomes pregnant with rhesus D positive fetus

At some point in the pregnancy, the blood from the fetus mixes with the blood in the mother’s blood stream

When this happens, the fetal red blood cells display the rhesus D antigen. The mother’s immune system will recognise the rhesus D antigen as foreign and produce antibodies to the rhesus D antigen. The mother has then become sensitised to rhesus D antigens.

Usually, this sensitisation process does not cause problems during the first pregnancy (unless the sensitisation happens early on, such as during antepartum haemorrhage).

During subsequent pregnancies, the mothers anti-D antibodies can cross the placenta into the fetus.

If that fetus is rhesus positive, these antibodies attach themselves to the red blood cells of the fetus and causes the immune system of the fetus to attack its own red blood cells.

This leads to haemolysis, causing anaemia and high bilirubin levels.

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18
Q

What does a direct Coombs test check for and when will it be positive?

A

A direct Coombs test (DCT) can be used to check for immune haemolytic anaemia. This will be positive in haemolytic disease of the newborn.

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19
Q

Two key causes of anaemia in older children?

A

Iron deficiency anaemia secondary to dietary insufficiency. This is the most common cause overall.
Blood loss, most frequently from menstruation in older girls

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20
Q

Causes of anaemia in older children?

A

Iron deficiency
Blood loss
Sickle cell anaemia
Thalassaemia
Leukaemia
Hereditary spherocytosis
Hereditary eliptocytosis
Sideroblastic anaemia

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21
Q

What is a common cause of chronic anaemia and iron deficiceny due to blood loss worldwide, although less common in the UK than in developing counteries?

A

Helminth infection, with roundworms, hookworms or whipworms

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22
Q

How is helminth infection, with roundworms, hookworms or whipworms treated?

A

Single dose of either

ALBENDAZOLE

or

MEBNDAZOLE

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23
Q

Causes of microcytic anaemia?

A

A helpful mnemonic for understanding the causes of microcytic anaemia is TAILS.

T – Thalassaemia
A – Anaemia of chronic disease
I – Iron deficiency anaemia
L – Lead poisoning
S – Sideroblastic anaemia

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24
Q

Causes of normocytic anaemia?

A

There are 3 As and 2 Hs for normocytic anaemia:

A – Acute blood loss
A – Anaemia of Chronic Disease
A – Aplastic Anaemia

H – Haemolytic Anaemia
H – Hypothyroidism

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25
Q

What is megaloblastic anaemia?

A

Subtype of macrocytic anaemia

Megaloblastic anaemia is the result of impaired DNA synthesis preventing the cell from dividing normally.

Rather than dividing it keeps growing into a large, abnormal cell.

This is caused by a vitamin deficiency.

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26
Q

Causes of megaloblastic anaemia?

A

B12 deficiency
Folate deficiency

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27
Q

Causes of normoblastic macrocytic anaemia?

A

Alcohol
Reticulocytosis (usually from haemolytic anaemia or blood loss)
Hypothyroidism
Liver disease
Drugs such as azathioprine

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28
Q

Causes of macrocytic anaemia?

A

Megaloblastic anaemia is caused by:

B12 deficiency
Folate deficiency
Normoblastic macrocytic anaemia is caused by:

Alcohol
Reticulocytosis (usually from haemolytic anaemia or blood loss)
Hypothyroidism
Liver disease
Drugs such as azathioprine

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29
Q

Symptoms of anaemia

A

Tiredness
Shortness of breath
Headaches
Dizziness
Palpitations
Worsening of other conditions
IRON DEFICIENCY: Pica, hair loss

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30
Q

Specific signs and symptoms of iron deficiency anaemia?

A

Pica (dietary cravings for abnormal things such as dirt)

Hair loss

Koilonychia refers to spoon shaped nails

Angular chelitis can indicate iron deficiency

Atrophic glossitis is a smooth tongue due to atrophy of the papillae

Brittle hair and nail

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31
Q

Bone deformities are a sign of which specific cause of anaemia?

A

thalassaemia (a microcytic anaemia)

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32
Q

Jaundice is a sign of what type of anaemia?

A

Haemolytic (a normocytic anaemia)

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33
Q

General signs of anazemia?

A

Pale skin
Conjunctival pallor
Tachycardia
Raised respiratory rate

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34
Q

Initial investigations for anaemia?

A

Full blood count for haemoglobin and MCV
Blood film
Reticulocyte count
Ferritin (low iron deficiency)
B12 and folate
Bilirubin (raised in haemolysis)
Direct Coombs test (autoimmune haemolytic anaemia)
Haemoglobin electrophoresis (haemoglobinopathies)

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35
Q

What are reticulocytes?

A

Immature red blood cells

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36
Q

What does high reticulocyte count suggest?

A

Reticulocytes are immature red blood cells.

A high level of reticulocytes in the blood indicates active production of red blood cells to replace lost cells.

This usually indicates the anaemia is due to haemolysis or blood loss.

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37
Q

The bone marrow requires iron to produce haemoglobin, if it is deficient it may result in a microcytic anaemia. There are several scenarios where iron stores can be used up and the patient becomes iron deficient, such as?

A

Dietary insufficiency. This is the most common cause in children.

Loss of iron, for example in heavy menstruation

Inadequate iron absorption, for example in Crohn’s disease

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38
Q

Most common cause of iron deficiency in children?

A

Dietary insufficiency

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39
Q

Why can PPIs lead to iron deficiency?

A

Iron is mainly absorbed in the duodenum and jejunum.

It requires the acid from the stomach to keep the iron in the soluble ferrous (Fe2+) form.

When there is less acid in the stomach, it changes to the insoluble ferric (Fe3+) form.

Therefore, medications that reduce the stomach acid, such as proton pump inhibitors (lansoprazole and omeprazole) can interfere with iron absorption.

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40
Q

Where is iron mainly absorbed?

A

Duodenum and jejunum

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41
Q

What autoimmune conditions may cause iron deficiency?

A

Conditions that result in inflammation of the duodenum or jejunum such as coeliac disease or Crohn’s disease can also cause inadequate iron absorption.

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42
Q

What is the soluble form of iron?

A

Ferrous - Fe2+

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43
Q

What is the insoluble form of iron?

A

Ferric - Fe3+

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44
Q

As what ions does iron travel around the blood?

A

Ferric - Fe3+ (bound to transferrin)

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45
Q

To which protein are ferric ions (Fe3+) bound when travelling around the blood?

A

Transferrin

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46
Q

How can transferrin saturation (transferrin molecules that are bound to iron) be calculated?

A

Measure the serum iron and total iron binding capacity

Transferrin Saturation = Serum Iron / Total Iron Binding Capacity

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47
Q

What is total iron binding capacity directly related to?

A

The amount of transferrin in the blood

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48
Q

What is Total iron binding capacity (TIBC)?

A

The total space on transferrin mocelcules for the iron to bind (therefore it is directly related to the amount of transferrin in the blood)

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49
Q

What is ferritin?

A

Ferritin is the form that iron takes when it is deposited and stored in cells.

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50
Q

What is the form that iron takes when it is depositied and stored in cells?

A

Ferritin

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51
Q

Why might ferritin be high regardless of other blood test results?

A

Extra ferritin is released from cells when there is inflammation, such as with infection or cancer.

High ferritin is difficult to interpret and is likely to be related to inflammation rather than iron overload.

A patient with a normal ferritin can still have iron deficiency anaemia, particularly if they have reasons to have a raised ferritin, such as infection.

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52
Q

What does low ferritin suggest?

A

If ferritin in the blood is low, this is highly suggestive of iron deficiency.

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53
Q

Why is serum iron not a very useful measure in itself when considering iron deficiency anaemia?

A

Varies significantly in the day - higher levels in morning and after meals containing iron

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54
Q

TIBC vs transferrin levels?

A

Total iron binding capacity can be used as a marker for how much transferrin is in the blood. It is an easier test to perform than measuring transferrin. Both TIBC and transferrin levels increase in iron deficiency and decrease in iron overload.

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55
Q

What parameter gives a good indication of total iron in the body?

A

Transferrin Saturation

(Transferrin Saturation = Serum Iron / Total Iron Binding Capacity)

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56
Q

Why is it best to do iron studies fasting?

A

Transferrin saturation gives a good indication of the total iron in the body. In normal adults it is around 30%, however if there is less iron in the body, transferrin will be less saturated. When iron levels go up, transferrin will be more saturated. It can increase shortly after eating a meal rich in iron or taking iron supplements, so a fasting sample is better.

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57
Q

What can increase the value of serum iron and serum ferritin,, and decrease the value of TIBC, giving the impression of iron overload?

A

Supplementation with iron
Acute liver damage (lots of iron is stored in the liver)

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58
Q

When is oral iron unsuitable?

A

Where malabsorption is the cause of the anaemia (e.g. inflamation of duodenum/jejunum)

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59
Q

What can be used to supplement iron orally?

A

ferrous sulphate or ferrous fumarate.

This slowly corrects the iron deficiency.

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60
Q

How can oral iron supplementation affect bowel habits/stool appearance?

A

Oral iron causes constipation and black coloured stools.

61
Q

What is leukaemia?

A

Leukaemia is the name for cancer of a particular line of the stem cells in the bone marrow.

This causes unregulated production of certain types of blood cells.

62
Q

What factors determine the classification of leukaemia?

A

How rapidly they progress (chronic is slow and acute is fast)

The cell line that is affected (myeloid or lymphoid).

63
Q

What is the most common form of leukaemia in children?

A

Acute lymphoblastic leukaemia (ALL)

64
Q

What types of leukaemia affect children?

A

Acute lymphoblastic leukaemia (ALL) is the most common in children

Acute myeloid leukaemia (AML) is the next most common

Chronic myeloid leukaemia (CML) is rare

65
Q

Acute lymphoblastic leukaemia (ALL) peak age of onset?

A

2 – 3 years

66
Q

Acute myeloid leukaemia (ALM) peak age of onset?

A

Under 2 years

67
Q

Basic pathophysiology of leukaemia?

A

Leukaemia is a form of cancer of the cells in the bone marrow.

A genetic mutation in one of the precursor cells in the bone marrow leads to excessive production of a single type of abnormal white blood cell.

The excessive production of a single type of cell can lead to suppression of the other cell lines, causing underproduction of other cell types.

This results in a pancytopenia, which is a combination of low: red blood cells (anaemia), white blood cells (leukopenia)and platelets (thrombocytopenia)

68
Q

What is pancytopenia?

A

Combination of low:
RBC (anaemia)
WBC (leukopenia)
Platelets (thrombocytopenia)

69
Q

Risk factors of leukaemia?

A

Radiation exposure, for example with an abdominal xray during pregnancy, is the main environmental risk factor for leukaemia.

There are several conditions that predispose to a higher risk of developing leukaemia:

Down’s syndrome
Kleinfelter syndrome
Noonan syndrome
Fanconi’s anaemia

70
Q

What conditions predispose to a higher risk of developing leukaemia?

A

Down’s syndrome
Kleinfelter syndrome
Noonan syndrome
Fanconi’s anaemia

71
Q

Presentation of leukaemia

A

The presentation of leukaemia is typically non-specific. Symptoms can include:

Persistent fatigue

Unexplained fever

Failure to thrive

Weight loss

Night sweats

Pallor (anaemia)

Petechiae and abnormal bruising (thrombocytopenia)

Unexplained bleeding (thrombocytopenia)

Abdominal pain

Generalised lymphadenopathy

Unexplained or persistent bone or joint pain

Hepatosplenomegaly

72
Q

NICE childhood leukaemia diagnosis guidance

A

NICE recommend referring any child with unexplained petechiae or hepatomegaly for immediate specialist assessment.

If leukaemia is suspected based on the non-specific signs above, NICE recommend a very urgent full blood count within 48 hours.

73
Q

Initial investigations for ?leukaemia?

A

Full blood count, which can show anaemia, leukopenia, thrombocytopenia and high numbers of the abnormal WBCs

Blood film, which can show blast cells

Bone marrow biopsy

Lymph node biopsy

74
Q

What might be seen on blood film in leukaemia?

A

Blast cells

75
Q

Further investigations for staging of leukaemia

A

Chest xray

CT scan

Lumbar puncture

Genetic analysis and immunophenotyping of the abnormal cells

76
Q

Management of leukaemia in children?

A

Treatment of leukaemia will be coordinated by a paediatric oncology multi-disciplinary team.

Leukaemia is primarily treated with chemotherapy.

Other therapies:
- Radiotherapy
- Bone marrow transplant
- Surgery

77
Q

Complications of chemotherapy?

A

Failure to treat the leukaemia

Stunted growth and development

Immunodeficiency and infections

Neurotoxicity

Infertility

Secondary malignancy

Cardiotoxicity

78
Q

ALL vs ALM prognosis

A

The overall cure rate for ALL is around 80%, but prognosis depends on individual factors.

The outcomes are less positive for AML.

79
Q

What is ITP?

A

Idiopathic thrombocytopenic purpura (ITP) is a condition characterised by idiopathic (spontaneous) thrombocytopenia (low platelet count) causing a purpuric rash (non-blanching rash).

80
Q

Key differentials for non blanching rash?

A

Meningococcal septicaemia

ITP (idiopathic thrombocytopenic purpura)

81
Q

What causes idiopathic thrombocytopenic purpura (ITP)?

A

ITP is caused by a type II hypersensitivity reaction. It is caused by the production of antibodies that target and destroy platelets.

This can happen spontaneously, or it can be triggered by something, such as a viral infection.

82
Q

What type of hypersensitivity reaction causes ITP?

A

Type II

83
Q

Presentation of idiopathic thrombocytopenic purpura?

A

Idiopathic thrombocytopenic purpura usually present in children under 10 years old.

Often there is a history of a recent viral illness. The onset of symptoms occurs over 24 – 48 hours:

  • Bleeding, for example from the gums, epistaxis or menorrhagia
  • Bruising
  • Petechial or purpuric rash, caused by bleeding under the skin
84
Q

Petechiae vs purpura vs ecchymoses

A

Petechiae are pin-prick spots (around 1mm) of bleeding under the skin.

Purpura are larger (3 – 10mm) spots of bleeding under the skin.

When a large area of blood is collected (more than 10 mm), this is called ecchymoses. These are all non-blanching lesions.

85
Q

How to confirm ITP?

A

The condition can be confirmed by doing an urgent full blood count for the platelet count.

Other values on the FBC should be normal.

Other causes of a low platelet count should be excluded, for example heparin induced thrombocytopenia and leukaemia.

86
Q

Is treatment always required for ITP?

A

The severity and management depends on how low the platelet count falls. Usually no treatment is required and patients are monitored until the platelets return to normal. Around 70% of patients will remit spontaneously within 3 months.

87
Q

When might treatment be required for ITP?

A

Treatment may be required if the patient is actively bleeding or severe thrombocytopenia (platelets below 10)

88
Q

What treatment if given if required (patient is actively bleeding or severe thrombocytopenia (platelets below 10)) in IPT?

A

Prednisolone
IV immunoglobulins
Blood transfusions if required
Platelet transfusions only work temporarily

89
Q

Why do platelet transfusions only work temporarily in idiopathic thrombocytopenic purpura (IPT)?

A

Platelet transfusions only work temporarily because the antibodies against platelets will begin destroying the transfused platelets as soon as they are infused.

90
Q

Idiopathic thrombocytopenic purpura (IPT) key education and advice?

A

Avoid contact sports

Avoid intramuscular injections and procedures such as lumbar punctures

Avoid NSAIDs, aspirin and blood thinning medications

Advice on managing nosebleeds

Seek help after any injury that may cause internal
bleeding, for example car accidents or head injuries

91
Q

Idiopathic thrombocytopenic purpura (IPT) - potential complications?

A

Chronic ITP
Anaemia
Intracranial and subarachnoid haemorrhage
Gastrointestinal bleeding

92
Q

What is sickle cell anaemia?

A

Sickle cell anaemia is a genetic condition that causes sickle (crescent) shaped red blood cells.

This makes the red blood cells fragile and more easily destroyed, leading to a haemolytic anaemia.

Patients with sickle cell anaemia are prone to various types of sickle cell crises.

93
Q

Pathophysiology of sickle cell anaemia?

A

Haemoglobin is the protein in red blood cells that transports oxygen.

During the development of a fetus, from 32 to 36 weeks gestation, the production of fetal haemoglobin (HbF) decreases.

At the same time, adult haemoglobin (HbA) is produced in greater quantities.

Over time there is a gradual transition from HbF to HbA. At birth, around half the haemoglobin produced is HbF and half is HbA.

By 6 months of age, very little fetal haemoglobin is produced.

Eventually, red blood cells contain almost entirely HbA.

Patients with sickle-cell disease have an abnormal variant called haemoglobin S (HbS).

HbS causes red blood cells to be an abnormal “sickle” shape.

Sickle cell anaemia is an autosomal recessive condition where there is an abnormal gene for beta-globin on chromosome 11.

One copy of the gene results in sickle-cell trait.

Patients with sickle-cell trait are usually asymptomatic.

Two abnormal copies are required for sickle-cell disease.

94
Q

Why is sickle cell disease more common in patients from areas traditionally affected by malaria, such as Africa, India, the Middle East and the Caribbean?

A

Having one copy of the gene (sickle-cell trait) reduces the severity of malaria.

As a result, patients with sickle-cell trait are more likely to survive malaria and pass on their genes.

Therefore, there is a selective advantage to having the sickle cell gene in areas of malaria.

95
Q

Diagnosis of sickle cell anaemia?

A

Pregnant women at risk of being carriers of the sickle cell gene are offered testing during pregnancy.

Sickle cell disease is also tested for on the newborn screening heel prick test at 5 days of age.

96
Q

Complications of sickle cell anaemia?

A

Anaemia

Increased risk of infection

Stroke

Avascular necrosis in large joints such as the hip

Pulmonary hypertension

Painful and persistent penile erection (priapism)

Chronic kidney disease

Sickle cell crises

Acute chest syndrome

97
Q

General management of sickle cell anaemia?

A

Avoid dehydration and other triggers of crises

Ensure vaccines are up to date

Antibiotic prophylaxis to protect against infection, usually with penicillin V (phenoxymethypenicillin)

Hydroxycarbamide can be used to stimulate production of fetal haemoglobin (HbF).

Fetal haemoglobin does not lead to sickling of red blood cells.

This has a protective effect against sickle cell crises and acute chest syndrome.

Blood transfusion for severe anaemia

Bone marrow transplant can be curative

98
Q

Sickle cell crisis is an umbrella term for a spectrum of acute crises related to the condition. These range from mild to life threatening. They can occur spontaneously or be triggered by stresses such as infection, dehydration, cold or significant life events.

There is no specific treatment for sickle cell crises and they are managed supportively - how?

A

Have a low threshold for admission to hospital

Treat any infection

Keep warm

Keep well hydrated (IV fluids may be required)

Simple analgesia such as paracetamol and ibuprofen (NSAIDs should be avoided where there is renal impairment)

Penile aspiration is used to treat priapism

99
Q

Types of sickle cell crisis?

A

Vaso-occlusive Crisis (AKA painful crisis)
Splenic Sequestration Crisis
Aplastic Crisis
Acute Chest Syndrome

100
Q

What is caso-occlusive crisis (aka painful crisis)

A

Type of sickle cell crisis caused by the sickle shaped blood cells clogging capillaries and causing distal ischaemia.

It is associated with dehydration and raised haematocrit.

Symptoms are typically pain, fever and those of the triggering infection.

It can cause priapism in men by trapping blood in the penis, causing a painful and persistent erection.

This is a urological emergency and is treated with aspiration of blood from the penis.

101
Q

What is splenic sequestration crisis?

A

Type of sickle cell crisis caused by red blood cells blocking blood flow within the spleen.

This causes an acutely enlarged and painful spleen.

The pooling of blood in the spleen can lead to severe anaemia and circulatory collapse (hypovolaemic shock).

Splenic sequestration crisis is considered an emergency.

Management is supportive, with blood transfusions and fluid resuscitation to treat anaemia and shock.

Splenectomy prevents sequestration crisis and is often used in cases of recurrent crises.

Recurrent crises can lead to splenic infarction, resulting in susceptibility to infections.

102
Q

What is Aplastic crisis?

A

Sickle cell crisis where there is temporary loss of the creation of new blood cells.

This is most commonly triggered by infection with parvovirus B19.

It leads to significant anaemia.

Management is supportive with blood transfusions if necessary.

It usually resolves spontaneously within a week.

103
Q

What does a diagnosis of acute chest syndrome require?

A

Fever or respiratory symptoms, with:
New infiltrates seen on a chest xray

104
Q

Why might acute chest syndrome occur?

A

Acute chest syndrome can be due to infection (e.g. pneumonia or bronchiolitis) or non-infective causes (e.g. pulmonary vaso-occlusion or fat emboli).

105
Q

How is acute chest syndrome managed?

A

Acute chest syndrome is a medical emergency with a high mortality. It requires prompt supportive management and treatment of the underlying cause:

Antibiotics or antivirals for infections
Blood transfusions for anaemia
Incentive spirometry using a machine that encourages effective and deep breathing
Artificial ventilation with NIV or intubation may be required

106
Q

Thalassaemia is related to a genetic defect in the protein chains that make up haemoglobin - how does the structure of Hb vary in normal haemoglobin, beta thalassemia and alpha thalassemia?

A

Normal haemoglobin consists of 2 alpha and 2 beta globin chains.

Defects in the alpha globin chains lead to alpha thalassaemia.

Defects in the beta globin chains lead to beta thalassaemia.

Both conditions are autosomal recessive. The overall effect is varying degrees of anaemia, depending on the type and mutation.

107
Q

What is the inheritance pattern of thalassemia?

A

Autosomal recessive

108
Q

Thalassaemia is related to a genetic defect in what?

A

the protein chains that make up haemoglobin

109
Q

Why does splenomegaly occur in thalassaemia?

A

In patients with thalassaemia the red blood cells are more fragile and break down more easily.

The spleen acts as a sieve to filter the blood and remove older blood cells.

In patients with thalassaemia, the spleen collects all the destroyed red blood cells, resulting in splenomegaly.

110
Q

What causes a susceptibility to fractures and prominent features, such as a pronounced forehead and malar eminences (cheek bones) in patients with thalassemia?

A

In patients with thalassaemia the red blood cells are more fragile and break down more easily.

In patients with thalassaemia, the spleen collects all the destroyed red blood cells

The bone marrow expands to produce extra red blood cells to compensate for the chronic anaemia

This causes a susceptibility to fractures and prominent features, such as a pronounced forehead and malar eminences (cheek bones).

111
Q

Thalassemia - potential signs and symptoms?

A

Microcytic anaemia (low mean corpuscular volume)

Fatigue

Pallor

Jaundice

Gallstones

Splenomegaly

Poor growth and development

Pronounced forehead and malar eminences

112
Q

What type of anaemia occurs in thalassemia?

A

Microcytic anaemia (low mean corpuscular volume)

113
Q

Thalassemia diagnosis

A

Full blood count shows a microcytic anaemia.

Haemoglobin electrophoresis is used to diagnose globin abnormalities.

DNA testing can be used to look for the genetic abnormality

Pregnant women in the UK are offered a screening test for thalassaemia at boo

114
Q

Why does iron overload occur in thalassemia?

A

Faulty creation of red blood cells
Recurrent transfusions
Increased absorption of iron in the gut in response to anaemia

115
Q

How is iron overload monitored for and subsequently managed in patients with thalassaemia?

A

Patients with thalassaemia have serum ferritin levels monitored to check for iron overload.

Management of iron overload involves limiting transfusions and performing iron chelation.

116
Q

Iron overload in thalassaemia causes what effects?

A

Fatigue
Liver cirrhosis
Infertility
Impotence
Heart failure
Arthritis
Diabetes
Osteoporosis and joint pain

117
Q

Alpha-thalassaemia is caused by defects in alpha globin chains. The gene coding for this protein is where?

A

On chromosome 16.

118
Q

Management of alpha-thalassaemia?

A

Monitoring the full blood count
Monitoring for complications
Blood transfusions
Splenectomy may be performed
Bone marrow transplant can be curative

119
Q

Beta-thalassaemia is caused by defects in beta globin chains. The gene coding for this protein is where?

A

On chromosome 11

120
Q

In beta-thalassaemia, the gene defect can either consist of abnormal copies that retain some function or deletion genes where there is no function in the beta globin protein at all.

Based on the type of defect, beta-thalassamia can be split into which three types?

A

Thalassaemia minor

Thalassaemia intermedia

Thalassaemia major

121
Q

What is thalassaemia minor and how is it managed?

A

Patients with beta thalassaemia minor are carriers of an abnormally functioning beta globin gene.

They have one abnormal and one normal gene.

Thalassaemia minor causes a mild microcytic anaemia and usually patients only require monitoring and no active treatment.

122
Q

What is thalassaemia intermedia and how is it managed?

A

Patients with beta thalassaemia intermedia have two abnormal copies of the beta globin gene.

This can be either two defective genes or one defective gene and one deletion gene.

Thalassaemia intermedia causes a more significant microcytic anaemia.

Patients require monitoring and occasional blood transfusions.

When they require more transfusions, they may require iron chelation to prevent iron overload.

123
Q

What is thalassaemia major and how and when will it present?

A

Patients with beta thalassaemia major are homozygous for the deletion genes.

They have no functioning beta globin genes at all.

This is the most severe form and usually presents with severe anaemia and failure to thrive in early childhood.

124
Q

What does thalassaemia major cause?

A

Severe microcytic anaemia
Splenomegaly
Bone deformities

125
Q

Management of thalassaemia major?

A

Regular transfusions
Iron chelation
Splenectomy

Bone marrow transplant can potentially be curative.

126
Q

What is the blood abnormality hereditary spherocytosis?

A

Hereditary spherocytosis is a condition where the red blood cells are sphere shaped, making them fragile and easily destroyed when passing through the spleen.

127
Q

Inheritance of hereditary spherocytosis?

A

Autosomal dominant

128
Q

What is the most common inherited haemolytic anaemia in northern Europeans?

A

Hereditary spherocytosis

129
Q

How does hereditary spherocytosis typically present?

A

Jaundice
Anaemia
Gallstones
Splenomegaly

130
Q

What is a haemolytic crisis (hereditary spherocytosis)?

A

Patients can have episodes of haemolytic crisis, often triggered by infections, where the haemolysis, anaemia and jaundice is more significant.

131
Q

What is an aplastic crisis (hereditary spherocytosis)?

A

Patients with hereditary spherocytosis can develop aplastic crisis.

During aplastic crisis there is increased anaemia, haemolysis and jaundice, without the normal response from the bone marrow of creating new red blood cells.

Usually the bone marrow will respond to haemolysis by producing red blood cells faster, demonstrated by extra reticulocytes (immature red blood cells) in the blood.

In aplastic crisis there is no reticulocyte response.

This is often triggered by infection with parvovirus.

132
Q

What often triggers an aplastic crisis?

A

Parvovirus infection

133
Q

If a patient affected by parvovirus develops anaemia and jaundice, what might be the underlying condition?

A

Hereditary spherocytosis (aplastic crisis)

134
Q

Diagnosis of hereditary spherocytosis?

A

Family history
Clinical features (anaemia, jaundice, gallstones, splenomegaly)
Spherocytes on the blood film

The mean corpuscular haemoglobin concentration (MCHC) is raised on a full blood count. Reticulocytes will be raised due to rapid turnover of red blood cells.

135
Q

Hereditary spherocytosis FBC abnormalities?

A

MCHC (mean corpuscular hb conc) raised
Reticulocytes raised (rapid turnover of RBC)
Normocytic anaemia

136
Q

Management of hereditary spherocytosis?

A

Treatment is with folate supplementation and splenectomy.

Removal of the gallbladder (cholecystectomy) may be required if gallstones are a problem.

Transfusions may be required during acute crises.

137
Q

Hereditary spherocytosis vs hereditary elliptocytosis

A

Hereditary elliptocytosis is very similar to hereditary spherocytosis except that the red blood cells are ellipse shaped.

It is also autosomal dominant.

Presentation and management are very similar.

138
Q

What is G6PD deficiency?

A

G6PD deficiency is a condition where there is a defect in the G6PD enzyme normally found in all cells in the body.

Causes a haemolytic anaemia

It is more common in Mediterranean, Middle Eastern and African patients. It is inherited in an X linked recessive pattern, meaning it usually affects males, as they have only a single copy of the gene on their single X chromosome. It causes crises that are triggered by infections, medications or fava beans (broad beans).

139
Q

Which sex is affected by G6PD deficiency?

A

Males - X linked recessive, males only have a single copy of the gene on their single X chromosome

140
Q

Inheritance pattern of G6PD deficiency?

A

X linked recessive

141
Q

What triggers crises in G6PD deficiency?

A

Infections
Medications such as anti malerial
Fava beans (broad beans)

142
Q

Presentation of G6PD deficiency?

A

G6PD often presents with neonatal jaundice.

Other features of the condition are:

Anaemia

Intermittent jaundice, particularly in response to triggers (infections, antimalerial medications, fava beans)

Gallstones

Splenomegaly

143
Q

Diagnosis of G6PD deficiency?

A

G6PD enzyme assay.

144
Q

Blood film in G6PD deficiency?

A

Heinz bodies may be seen on a on blood film.

Heinz bodies are blobs of denatured haemoglobin (“inclusions”) seen within the red blood cells.

145
Q

G6PD deficiency pathophysiology

A

G6PD DEFICIENCY MAKES CELLS MORE VULENERABLE TO ROS, LEADING TO HAEMOLYSIS IN RBC

The G6PD enzyme is responsible for helping protect cells from damage by reactive oxygen species (ROS).

ROS are reactive molecules that contain oxygen, produced during normal cell metabolism and in higher quantities during stress on the cell.

The G6PD enzyme is particularly important in red blood cells.

A deficiency in G6PD makes cells more vulnerable to ROS, leading to haemolysis in red blood cells. *****

Periods of increased stress, with a higher production of ROS, can lead to acute haemolytic anaemia.

146
Q

What is the role of the G6PD enzyme?

A

The G6PD enzyme is responsible for helping protect cells from damage by reactive oxygen species (ROS).

147
Q

When managing G6PD deficienct, the patient should avoid triggers to acute haemolysis where possible. This includes avoiding fava beans and certain medications.

Medications that trigger haemolysis and should be avoided include what?

A

Primaquine (an antimalarial)

Ciprofloxacin

Nitrofurantoin

Trimethoprim

Sulfonylureas (e.g gliclazide)

Sulfasalazine and other sulphonamide drugs

148
Q

When might lymphadenopathy be normal in children

A
  1. Bilateral anterior cervical LNs up to 2cm in diameter often found in healthy older children,
    or if recovering from an URTI.
  2. Bilateral axillary LNs up to 1cm in diameter and inguinal LNs up to 1.5cm in diameter also
    often found in older children. May be found in younger children with eczema
149
Q

Concerning lymphadenopathy in children

A
  1. Supraclavicular LNs of any size at any age often reflect mediastinal disease and should
    always prompt investigation.
  2. Nodes that are firm, variable in size, non-tender and matted together warrant further
    investigation as they can be associated with malignancy.
  3. Nodes of variable size and consistency – consider TB.
  4. Skin changes over the enlarged node (erythema, warmth, LN tenderness and fluctuation
    suggest lymphadenitis and an infective origin.
  5. Rule of ‘2’s: investigate if: >2 LN palpable for >2 weeks
    >2cm in size
    2 or more regions affected

Year 4 Paediatrics (18 decks)

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