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Haematology And Oncology Notes

Medicine Notes > Paediatrics Notes

This is an extract of our Haematology And Oncology document, which we sell as part of our Paediatrics Notes collection written by the top tier of University Of Nottingham students.

The following is a more accessble plain text extract of the PDF sample above, taken from our Paediatrics Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Haematology and Oncology Types of Hb

*

Embryonic Hb Gower 1, Hb Gower 2, Hb Portland

*

Fetal HbF (holds onto oxygen better than HbA oxygen dissociation curve shifts to the right at birth
[offloads oxygen more readily])

*

Adult HbA (97%), HbA

2 *
Anaemia

*

*

Hb below the normal range

o

Neonate <14g/dl

o

112 months <10g/dl

o

112 years <11g/dl

Anaemia may be due to:

o

o

o

Reduced RBC productionRed cell aplasiaIneffective erythropoiesis

*

Fe deficiency

*

Folid acid deficiency

HaemolysisRed cell membrane disorders hereditary spherocytosisRed cell enzyme disorders glucose6 phosphate dehydrogenase deficiencyHaemoglobinopathies thalassaemias, sickle cellImmune haemolytic disease of the newborn, autoimmune

Blood loss

Anaemia Due To Reduced Red Cell Production

*

*

Ineffective erythropoiesis differentiation and survival of RBCs is defective

o

Reticuloctye count will be normal

o

MCV will be abnormalLow in iron deficiencyHigh in folate deficiency

Complete absence of RBC production in red cell aplasia

o

Low or absent reticulocyte count

o

CausesCongenital - DiamondBlackfan anaemiaTransient erythroblastopenia of childhoodParvovirus B19 (only in those with inherited haemolytic anaemias)

Iron Deficiency

*

Term newborn iron stores of 250mg

*

Adult iron stores of 45g

*

Causes

o

Inadequate intake common in infantc*

1 year old requires 8mg/day

o

Malabsorption

o

Blood loss

Iron sources

o

Breast milk - low content but 50% of iron is absorbed

o

Infant formula

o

Cow's milk - higher content than breast but only 10% absorbed

o

Solids introduced at weaning

*

Increase absorption with Vitamin C

*

Clinically

*

o

Asymptomatic until Hb drops below 7g/dl

o

Tire easily

o

Feed slowly

o

Pallor (esp. conjunctivae, tongue or palmar creases)

o

Pica

Diagnosis

o

Microcytic, hypochromic anaemia (low MCV and MCH)o

*

[?][?]; B/athallassaemia, anaemia of chronic disease

Low serum ferritin

Management

o

Dietary advice

o

Oral supplementationContinue until Hb is normal and for a further 3 months

o

Blood transfusion should NEVER be necessary for dietary iron deficiency

Increased Red Cell Destruction

*

Increased destruction either in the circulation (intravascular) or in the liver/spleen (extravascular)

*

Haemolysis only leads to anaemia when the bone marrow can no longer compensate

*

Main cause in children is intrinsic abnormalities of the RBC

*

*

o

Red cell mebrane disorders (hereditary spherocytosis)

o

Red cell enzyme disorders (G6PD deficiency)

o

Haemoglobinopathies (thalassaemia, sickle cell)

Haemolysis leads to:

o

Anaemia

o

Hepatomegaly

o

Splenomegaly

o

Increased blood levels of unconjugated bilirubin

o

Excess urinary urobilinogen

Diagnosis

o

Raised reticulocyte count (polychromasia)

o

Unconjugated bilirubinaemia and increased urinary urobilinogen

o

Abnormal appearance of red cells on blood film

o

Positive direct antiglobulin test (Coomb's) [only in immune cause]

o

Increased red cell precursors in the bone

Hereditary Spherocytosis

*

1 in 5000 caucasian births

*

Autosomal dominant

*

Mutations in genes coding for red cell membrane proteins spectrin, ankyrin or band 3

*

Reduction in surface to volume ratio spheroidal destruction in the spleen

*

Clincally

o

Suspected due to family history

o

Jaundice intermittent during childhood OR severe jaundice in the first few days of life

o

Anaemia mild (911g/dl)

o

Mild/moderate splenomegaly

o

Aplastic crisis transient due to parvovirus B19

o

Gallstones due to increased bilirubin

*

Diagnosis

o

Blood film

o

[?][?] Autoimmune haemolytic anaemiaExcluded with a direct antibody test in the absence of a family history of hereditary spherocytosis

*

Management

o

Oral folic acid

o

Splenectomy is indicated for poor growth or troubelsome symptoms of anaemia

oDefer until 7 years oldVaccinated against Hib, Meningitis C and strep. Pneumoniae beforehandLifelong daily oral penicillin prophylaxis

Aplastic crisis1 or 2 blood tranfusions over 34 weeks when no RBCs are produced

Glucose6 Phosphate Dehydrogenase Deficiency

*

High prevalence in those originating from central Africa, the Mediterranean, the Middle East and the Far East

*

Rate limiting enzyme in the pentose phosphate pathway and prevents oxidative damage to RBCs

*

X linked and therefore largely affects males

*

Clinically

*

o

Neonatal jaundice

o

Acute haemolysis precipitated by:InfectionDrugs antimalarials, sulphonamides, quinolones, nitrofuratoinFava bean

o

Intravascular haemolysis fever, malaise

o

Dark urine - urobilinogen and Hb

Diagnosis

o

Measure G6PD activity in RBCs

o

During a crisis the G6PD levels may be mistakingly elevated due to higher enzyme concentration in reticulocytes

*

Management

o

Info regarding signs of acute haemolysis (jaundice, dark urine)

o

And list of druge, chemicals and food to avoid

Haemoglobinopathies

*

Reduced or absent production of HbA (thalasaemia) or production of abnormal Hb (sickle cell)

Sickle Cell

*

1 in 2000 live births

*

Most common in patients who have black parents and originate from tropical Africa or the Caribbean

*

Mutation in codon 6 of the B globin chain HbS forms

*

Clincal manifestation is delayed until 6 months when the HbF has all but disappeared

*

Three main forms of disease and the sickle cell trait

o

Sickle Cell Anaemia (HbSS)o

Homzygous for HbS

HbSC DiseaseHbS from one parent and HbC from the other

*

o

o

*

HbC forms due to a different point mutation in B globinNo HbA - as no normal B globin genesDevelop proliferative retinopathyOsteonecrosis of hips and shoulders

Sickle B thalassaemiaHbS from one parent and B thalassaemia trait from the otherNo normal B globin genes

Sickle TraitHbS from one parent and a normal B globin chain from the other40% of Hb is HbSCarriersAsymptomatic

Clinical Features

o

Anaemia moderate anaemia with detectable jaundice

o

Infection

oEsp. from encapsulated organisms (pneumococci, Hib)Osteomyelitis due to SalmonellaDue to hyposplenism secondary to microinfarction in the spleen

Painful Crises

o

oVasoocclusive crisisDactylitis with pain and swelling in the hands and feet in late infancyBones of the limbs and spine are commonest sitesPrecipitated by cold, dehydration, exercise, stress, hypoxia and infection

Acute Chest Syndrome - type of painful crisisLeads to hypoxia and need for mechanical ventilation(Emergency transfusion)

Acute anaeimaSudden drop in Hb due to:

*

Haemolytic crisis (due to infection)

*

Aplastic crises (Parvovirus causes complete, temporary cessation)

*

Sequestration crises - sudden splenic or hepatic enlargement, abdo pain and circulatory collapse from accumulation of sickle cells in spleen

o

Priapism

o

Splenomegaly

o

Long termShort stature and delayed pubertyStroke (1 in 10)

*

2x this develop more subtle neuro damage (poor concentration and school performance)

*Adenotonsillar hypertrophy - sleep apnoeaCardiac enlargementHF - from uncorrected anaemiaRenal dysfunctionPigment gallstonesLeg ulcers

Management

o

o

ProphylaxisFull immunisation (pneumococcal, Hib, meningococcus)Daily oral penicillin throughout childhood (Vs. pneumococcus)Once daily folic acid due to increased demandAvoid exposure to triggers of vasoocclusive crisis

Treatment of acute crisis

oAnalgesiaHydrationInfection requires antibioticsExchange transfusion acute chest syndrome, priapism, stroke

Treatment of chronic problemsRecurrent painful vasoocclusive crises or acute chest syndrome hydroxyurea increases HbF

*Bone marrow transplant if unresponsive only cure

*

*

S/E - WBC suppression

Only safely carried out with an HLA identical twin

Diagnosis and Screening

o

Guthrie

o

Prenatal diagnosis by chorionic villus sampling at the end of the 1st trimester

o

50% with the most severe form die by 40 years of age

B Thalassaemias

*

Most commonly in people from the Indian subcontinent, Mediterranean and Middl East

*

Two main types both involve a sever reduction in B globin hence HbA

o

o

*

B Thalassaemia majorSevereHbA cannot be produced

B Thalassaemia IntermediaMilder / variable severitySmall amount of HbA and/or large amounts of HbF are produced

Clinical Features

o

Severe anaemia - transfusion dependent from 36 months

o

Jaundice

o

FTT

o

Extramedullary haemopoiesisPrevent with transfusionAbsence of tranfusion = hepatosplenomegaly and bone marrow expansion

*

*

Management

Maxillary overgrowth and skull bossing

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