Iron-deficiency, Haemolytic and Sickle Cell Flashcards
PPx and Aetiology of Iron deficiency Anaemia?
- Results in anaemia due to ineffective erythropoiesis, red cell production occurs at a normal rate but differentiation/survival of red cells are defective as iron required for production of haem.
- MICROCYTIC (SMALL RBC).
- Can occur due to inadequate intake, malabsorption, blood loss (Meckel’s/oesophagitis).
What are sources of iron?
High: Red meat, liver, kidney, oily fish
Average: Pulses, beans, broccoli, nuts, fortified cereals.
Food to avoid in excess: Cows milk, Tea (tannin inhibits iron uptake).
Clinical presentation of Iron-deficiency anaemia?
- Asymptomatic until haemoglobin levels drop significantly.
1) Tire easily/fatigue
2) Feed poorly
3) Pallor
4) Less happy - reduces psychomotor and cognitive development
Treatment of iron-deficiency anaemia?
1) Dietary advice: red meat, oily fish, cereals etc.
2) Oral iron: Ferrous fumerate syrup or sodium iron edetate.
3) Iron supplementation should be continues until haemoglobin levels are normal and for a further 3 months minimum to replenish iron stores.
Failure to respond to therapy:
Either poor compliance or malabsorption.
Haemolytic Anaemia (pathophys):
- Characterised by reduced red blood cell lifespan - increased blood cell destruction in circulation, liver, spleen.
- In haemolysis red cell survival (usually 120d) may be reduced to a few days but bone marrow production of RBC’s can increase 8-fold, haemolysis only leads to anaemia when the bone marrow is no longer able to compensate for premature destruction.
- Haemoglobinopathies such as B-thalassaemia and sickle cell are main causes of haemolytic anaemia.
Haemolysis from increased blood cell breakdown leads to:
1) Anaemia
2) Hepatomegaly, Splenomegaly
3) High levels of unconjugated bilirubin
4) Excess urobilinogen
Diagnostic clues to haemolysis?
1) Raised reticulocyte count
2) Unconjugated bilirubinaemia
3) Abnormal appearance on blood film
4) Increased RBC precursors in bone marrow
Haemoglobin makeup and levels?
Normal Hb (HbA) - haem, 2 alpha, 2 beta chains Foetal Hb (HbF) - haem, 2 alpha, 2 gamma chains Hb delta (HbA2) - haem, 2 alpha, 2 delta chains In a normal adult (HbA - 97%, HbA2 - 2%, HbF - 1%)
Sickle Cell Anaemia Ex, RF?
- A disorder of quality (abnormal molecule or variant haemoglobins).
- Epidemiology: Commonest genetic disorder in children, common in Africa, India, Middle East, Southern Europe.
- Autosomal recessive condition: 1 in 4 chance of being affected, 50% chance carrier, 1 in 4 chance being disease free.
- Abnormal production of Beta-globin chains.
RF: African, FH
Sickle Cell pathophys:
Heterozygous state (sickle cell trait) only carrier, as only chromosome carries this gene. Homozygous state - both chromosomes carry abnormal gene - have the disease.
- Disease only manifests itself at 6 months, when HbF (foetal/gamma) decreases to adult levels as HbF is unaffected.
- Membrane flexibility of sickle cell haemoglobin (HbS) is decreased and become more rigid taking up sickle shape.
- Sickling results in - shorted RBC survival (haemolysis) and difficulty passing through microcirculation (obstruction of small vessels - infarction and thus intense pain).
- Sickling precipitated by cold, infection, dehydration, hypoxia, acidosis.
- HbS releases oxygen more readily than normal haemoglobin thus patients feel well despite being anaemic (except in crisis/complications).
Sickle Cell trait (heterozygous) clinical presentation?
Heterozygous sickle cell trait:
1) Symptom free with no disability except in hypoxia (unpressurised aircraft/anaesthesia where vasoocclusive events may occur).
2) Carriage - protects against falciparum malaria
Sickle Cell (homozygous) clinical presentation?
1) ANAEMIA - moderate anaemia with clinically detectable jaundice from chronic haemolysis.
2) INFECTION - increased susceptibility to infection from encapsulated bacteria such as pneumococci and haemophilia influenzae, increased his of osteomyelitis from Salmonella. Susceptibility as a result of hyposplenism secondary to chronic sickling and micro-infarction in spleen. Risk of overwhelming sepsis is greatest in childhood.
3) Vaso-occlusive crises - acute pain in hand and feet (dactylics) due to vasoocclusion of small vessels and avascular necrosis of bone marrow in children. CNS infarction possible in children - strokes, seizures, neuro deficits.
4) Acute chest syndrome - A vasoocclusive crisis of the pulmonary vasculature (occurs in 30%), can result in chest pain, breathlessness, hypoxia - may require mechanical ventilation and emergency transfusion.
5) Acute anaemia:
- Haemolytic crisis - (associated with infection)
- Aplastic crisis - Parovirus infections causing complete cessation of red blood cell production.
- Sequestration crisis - Sudden hepatic or spleen enlargement, abdominal pan and circulatory collapse due to accumulation of sickled cells in spleen.
(ANAEMIA, INFECTION, VASO-OCCLUSIVE CRISES, ACUTE CHEST SYNDROME, ACUTE ANAEMIA)
Long-term problems of sickle cell anaemia?
1) Growth and development - short but regain height in adulthood, remain below weight, sexual maturation delay.
2) Bones - common site for vast-occlusive crisis resulting in chronic infarcts, avascular necrosis of the hips and shoulders, and shortening of bones in hands and feet, compression of vertebrae, osteomyelitis (salmonella, strep, staph)
3) Infections in bones, kidneys and lungs (most susceptible to vaso-occlusive crisis)
4) Cardiac - Cardiomegaly, arrhythmia, iron overload cardiomyopathy, MI)
5) Neuro - Increased risk of stroke, poor concentration and school performance
6) Renal dysfunction - exacerbate enuresis (due to inability to concentrate urine)
7) Psychosocial problems - difficulties with education and behaviour exacerbated by time off school.
Diagnosis of sickle cell anaemia?
1) Diagnosed prenatally with Guthrie test (enables prophylactic penicillin).
2) Blood count - Hb: 60-80 g/L, RAISED RETICULOCYTES
3) Blood film - Sickled erythrocytes shown
4) Sickle solubility test - POSITIVE
5) Hb electrophoresis: CONFIRMS DX - shows 80-95% HbS with NO HbA. Aim for diagnosis at birth (with cord blood) to enable pneumococcal prophylaxis
Treatment of sickle cell anaemia?
1) Vaso-occlusive crises minimised - avoid cold, excess exercise, dehydration, undue stress and hypoxia.
2) Folic acid for all haemolysis patients
3) Prophylactic penicillin against pneumococcal bacteria (Oral penicillin)
4) Acute painful attacks - IV fluids, analgesia (morphine, codeine, paracetamol, NSAIDs), Oxygen and antibiotics if required
5) Anaemia:
1) Blood transfusion (increased risk of iron overload) given for: Acute Chest syndrome, Acute Anaemia (splenic sequestration), aplastic crisis, stroke, heart failure.
2) Oral hydroxycarbamide: Increases HbF concentrations - helping protect against further crisis.
3) Bone marrow transplant - CURATIVE (required HLA-identical sibling)
