Haematology 1 Flashcards
What is the site of haematopoiesis?
Mainly liver in fetal life.
Bone-marrow in post-natal life.
When are stores of iron, folic acid and Vitamin B12 low?
In preterm infants - depleted quickly in the first few months of life.
What is anaemia in different age groups
Neonate Hb < 14
1-12 months Hb <10
1-12 years Hb <11
What is the platelet count in children compared to adults?
Similar to that of an adult:
150-450x10^9
It increase to 270-570 (1-6months)
What is the pattern of normal WCC in children
Highest in newborn to 2 years.
Slowly declines until adulthood
Change in Haemoglobin from fetal to neonatal life?
Most important difference.
Foetal Hb is made of 2 alpha + 2 gamma units (higher affinity for oxygen)
Adult Hb is made of 2 alpha + 2 beta units
HbF is gradually replaced by HbA in the first year of life
What are the changes in Hb concentration in a newborn
At birth, Hb is HIGH (14-21.5g/dl)
-to compensate for the low O2 concentration in the fetus
Hb falls over the first few weeks because of RBC production.
10g/dl at 2 months of age
What are the general causes of IDA
Inadequate intake Malabsorption Blood loss (rare)
Why is IDA common in infants?
Additional iron is required for the increase in blood volume accompanying growth and also to build up iron stores
The role of diet in maintaining normal iron
Breast milk, formula or cow’s. Later solids!
Delay in weaning beyond 6 months can lead to IDA
Best absorbed with Vitamin C.
Tannin from tea reduces absorption.
Diagnosis of IDA in infants
Clinical features present < 6-7g/dl
Easily fatigued
Feed more slowly
Pale (confirm on conjunctiva, tongue, palmar crease)
Microcytic, hypochromic anaemia (low MCV and MCH) and low serum ferritin
Management of IDA
Dietary advice!
Oral supplementation if needed
If still no gain, investigate malabsorption
Foods to avoid in excess for toddlers:
cow’s milk, tea (tannin), high fibre foods (phytates inhibit)
Average iron:
pulses, beans, peas
fortified breakfast cereal with added Vit C
Wholemeal products
Dark green vegetables (broccoli, spinach)
Raisins, sultanas
Nuts and seeds (cashew/peanut butter)
HIGH in iron:
Red meat
Liver/kidney
Oily fish
What are the effects of folate and vit B12 deficiency on blood cells?
Folate provides constituents to produce red cells.
Without them the body cannot make enough cells:
Macrocytic megaloblastic anaemia
B12 vital for DNA synthesis so similar effect
Neutrophil and lymphocyte count changes with age
Slight drop with age
Effect of malignant disorder of the blood on WCC
Can be both high or low
Generally a drop in WCC
What is haemolytic anaemia
Lifespan of normal red cell is 120 days. Reduced in haemolysis (either intravascular or extravascular haemolysis)
If it is reduced to the point where bone marrow cannot compensate (production can increase about 8fold)
Main causes of haemolysis in neonates and children
Neonates - immune haemolytic anaemia is common
In children, uncommon: mainly caused by intrinsic abnormalities of RBC
- RBC membrance disorders (eg. hereditary spherocytosis)
- Red cell enzyme disorders (G6PD deficiency)
- Haemoglobinopathies (abnormal haemoglobins eg. ß-thalassaemia major, sickle cell disease)
Symptoms and signs of haemolysis
Anaemia
Hepatomegaly and splenomegaly
Increased serum unconjugated bilirubin
Excess urinary urobilinogen
Diagnostic markers for haemolysis
Raised reticulocyte count (polychromasia - lilac)
Unconjugated bilirubinaemia and increased urinary urobilinogen
Abnormal appearance of RBC on blood film - eg. spherocytes, sickle shaped or very hypochromic
Positive direct antiglobulin test (identified antibody coated RBCs)
Increased RBC precursors in bone marrow
What is hereditary spherocytosis (pathophysiology)
Usually autosomal dominant inheritance. In 25% it is a new mutation
Mutations in genes for protein in RBC membrane. (spectrin, ankyrin)
Reduces survace to volume ratio - become spheroidal. Less deformable and thus destroyed in the microvasculature of the spleen.
Clinical features of hereditary spherocytosis
Jaundice - usually during childhood. May be severe in first few days of life
Anaemia - mild anaemia, but Hb level may transiently fall during infections
Mild to moderate hepatosplenomegaly
Gallstones (due to increased bilirubin excretion)
Aplastic crisis (uncommon transient)
Diagnostic test for spherocytosis
Blood film
Spherocytes may also occur in autoimmune haemolysis: exclude with direct antibody test if no FHx
What is G6PD deficiency
Glucose 6 phosphate dehydrogenase deficiency
It is a rate-limiting enzyme in preventing oxidative damage to RBCs
X-linked: predominantly affects males
Presentation of G6PD
Neonatal jaundice - usually first 3 days of life
Acute haemolysis, precipitated by:
- infection (most commonly)
- fava beans
- certain drugs
Predominantly intravascular haemolysis leading to an acute picture:
jaundice
pallor
fever, malaise, passage of dark urine (Hb+urobilinogen)
Intermittent haemolytic crises
Ethnically, most affected are central Africa, Mediterranean, middle East, far East
Diagnosis of G6PD deiciency
measure G6PD activity in RBC
However, may be elevated in a haemolytic crisis, so repeat assay in the steady state is required
What are haemoglobinopathies?
RBC disorders which cause haemolytic anaemia because of reduced/absent production of HbA (alpha and beta thalassaemia) or because of the production of abnormal Hb (sickle cell)
What are thalassaemias
Alpha is caused by deletions in the alpha-globin gene
Beta and sickle cell disease are caused by mutation in the beta globin gene
When do haemoglobinopathies present
Alpha thalassaemia from newborn period (maybe even fetus?)
Beta thalassaemia and Sickle cell only after 6 months after birth - most HbF replaced by adult HbA
