Haemotology Flashcards
What is haematopoesis?
Commitment and differentiation process of a stem cell to the different types of cells in blood
Where does haematopoesis occur?
**Adults: **
Mainly in bone marrow: pelvis, vertebrae,sternum (known as medullary haematopoesis).
Can occur in liver, thymus and spleen (known as extra medullary haematopoesis)
Where does haematopoesis occur as a foetus
Liver and Spleen
Describe haematopoesis throughout life
Role of erythrocyte?
Transport Oxygen around body
What is erythropoesis
Production of red blood cells
Red blood cell removal occurs in
Spleen
Liver
Bone Marrow
What factor/hormone affects erythropoesis
HYPOXIA: Decrease in oxygen
Stimulates kidneys to produce erythropoetin
What occurs once reticulocyte enter circulation
Red Blood Cell Removal
Red Blood Cell Production
Composition of blood
Where do platelets come from?
Role of platelets?
Help form clots together with clotting factors
What are leukocytes subdivided into
Granulocytes:White blood cells containing pathogen combating granules
Agranulocytes: White blood cells that dont contain pathogen combating granules
What are the 3 main granulocytes
What do agranulocytes divide into?
What is anaemia?
Low haematocrit.
Level <120 g/L in females and <140 g/L in males
RBC importance
Carry O2 and CO2 as well as maintaining blood pH
Where do erythrocytes originate from
Myeloid progenitor cells
Hormones involved in myeloid progenitor -> reticulocyte
Erythropoetin
Thyroid Hormone
Androgens
How do you identify anaemia
Take a full blood count and look at the mean corpuscular volume (average size of persons red blood cell)
Classifications of anaemia
Microcytic anaemia (<80fl)
Normocytic (80-100fl)
Macrocytic (>100fl)
Causes of microcytic anaemia (<80fl)
Iron deficiency
Chronic Inflammatory Disease
Thalassaemia
Investigations carried out for microcytic anaemia
Iron studies
+/- Mentzer Index
Investigations for normocytic anaemia
Reticulocyte Count
Investigations for macrocytic anaemia
Causes of anaemia
- Decreased production of erythropoesis
- Blood Loss
- Increased destruction
Reasons for a decreased production of erythropoesis
Reasons for increased production leading to anaemia
Disseminated Intravascular Coagulation
Thrombotic Thrombocytopenic Purpura
Hemolytic uremic syndrome
What does a red blood cell release when they get destroyed?
Lactate Dehydrogenase
Haemoglobin:
-Globin
-Unconjugated bilirubin
-iron
Blood Test in haemolytic anaemia
Clinical Presentation with someone having anaemia
Types of microcytic anaemia
Fe deficiency
Alpha & Beta Thalassemia
Sideroblastic
What is iron deficiency anaemia
Anaemia due to a decrease in iron
Iron deficiency symptoms?
Anaemia
Fatigue
Headache
Palpitations
Pallor
Nausea
Iron Deficiency
Pica (Pica is the abnormal craving or appetite for non-food substances, such as dirt, ice, paint, or clay.)
Nail changes (koilonychia-spoon shaped nails)
Hair Loss
Glossitis and Angular stomatitis
Restless Leg Syndrome
Patients with iron deficiency anemia are often asymptomatic and have limited findings on examination.
Remember Elder patient presenting with iron deficiency must be investigated for colon cancer malignancy even in the absence of Foecal blood
Risk Factors or Fe2+ anaemia
Decrease in the iron intake or impaired Absorption
Vegan diet
Low socioeconomic status
Gastrectomy
Coeliac Disease
Increase in iron loss
Menorrhagia
Hookworm
NSAID use
Gastrointestinal Bleeding
Increase in iron demand
Pregnancy
Infancy
Side note Our body needs iron 1mg/day. Pregnant women need 5-6mg/day
Differential diagnosis for Fe2+ anaemia
Anaemia
Vitamin B12 deficiency
Folate deficiency
Thalessemia - also hypochromic and microcytic
Anaemia of chronic disease
Sideroblastic
Iron Disorder
Atransferrinaemia
Lead toxicity
Investigations for Fe2+ anaemia
The lower the haemoglobin the more likely there is to be serious underlying pathology and the more urgent is the need for investigation. Patients without a clear physiological explanation for iron deficiency (especially men and postmenopausal women) should be evaluated by gastroscopy/colonoscopy to exclude a source of gastrointestinal bleeding, particularly a malignant lesion.
Full blood count
Haemoglobin/Haematocrit: decreased
Mean cell volume (MCV): decreased
Red cell distribution of width: increased because as iron decreases cells become smaller, increasing distribution
Think In anaemia of chronic disease, the RDW decreases the red blood cells of similar size.
Peripheral blood smear: microcytic, hypochromic red blood cells
Iron studies
Serum iron: decreased
Total iron-binding capacity: increased
Transferrin Saturation: decreased (transferrin is being overproduced to compensate for low iron)
Serum Ferritin: reduced. Ferritin reflects iron stores and is the most accurate test to diagnose iron deficiency anaemia.
Endoscopy: check for peptic ulcer disease, coeliac disease, and other gastrointestinal bleeding conditions
Colonoscopy
Coeliac disease screening at any age?
Remember, IDA may be effectively diagnosed by full blood examination and serum ferritin level in most cases. Serum iron levels should not be used to diagnose iron deficiency.
Side note A complete blood count can help determine the mean corpuscular volume or red blood cell size. Although iron deficiency is the most common cause of microcytic anaemia, up to 40 per cent of patients with iron deficiency anaemia will have normocytic erythrocytes.
Diagnosis for Fe2+ anaemia
Diagnosis of iron deficiency anaemia requires laboratory-confirmed evidence of anaemia and evidence of low iron stores. Anaemia is defined as a haemoglobin level two standard deviations below normal for age and sex.
Think: Iron deficiency anaemia and thalassaemia trait are the commonest causes of microcytic anaemia, but they may coexist. Serum ferritin and haemoglobin A2 quantitation are the two most important investigations to distinguish between iron deficiency anaemia and thalassaemia trait
Causes of Fe2+ anameia
Once iron deficiency anaemia is identified, the goal is to determine the underlying aetiology.
Decreased iron intake
Poverty
Starving
Patient not taking oral iron therapy
Patient taking an iron supplement or multivitamin tablet with insufficient iron content
Inadequate diet or impaired absorption
Concomitant consumption of inhibitors of iron absorption (eg, tea, calcium, antacids, tetracycline, within 2 hours of iron ingestion)
Coexisting inflammation with functional iron deficiency
Intestinal mucosal disorders (eg, coeliac disease, inflammatory bowel disease)
Impaired gastric acid secretion (including use of proton pump inhibitors)
Gastric/intestinal bypass procedures
Helicobacter pylori colonisation
Controlled-release iron formulations may contribute (ie, potential for limited iron absorption in some patients
Increased iron loss
Occult, undiagnosed or recurrent gastrointestinal blood loss (eg, peptic ulcer, malignancy, angiodysplasia, small bowel lesion, parasites)
Other source of recurrent blood loss (eg, menorrhagia due to uterine pathology or an inherited bleeding disorder such as von Willebrand disorder)
Multiple sources of recurrent blood loss (eg, hereditary haemorrhagic telangiectasia)
Ongoing urinary iron losses (eg, significant valve haemolysis)
Renal failure responding to erythropoietin-stimulating agents
Increased iron requirements
Coexisting condition interfering with bone marrow response
Superimposed infection, inflammation, malignancy or renal failure
Concomitant B12 or folate deficiency
Coexisting primary bone marrow disease or suppression
Unknown cause (congenital iron deficiency)
Patients with an underlying condition that causes iron deficiency anemia should be treated or referred to a subspecialist (e.g., gynecologist, gastroenterologist) for definitive treatment.
Remember Gastrointestinal, Genitourinary sources of bleeding should always be excluded
Pathophysiology of Fe2+ anaemia
- Iron is required to form the haem moiety in haemoglobin, myoglobin, and haem enzymes, also known as cytochromes.
- Iron can also be stored in the form of ferritin
- Iron Deficiency can be a result of:
Decreased iron intake because of inadequate diet or impaired absorption
Increased iron loss
Increased iron requirements
Depletion of Iron stores - Anaemia then results in decreased oxygen-carrying capacity and the resultant symptoms of fatigue, low energy level, and dyspnoea on exertion.
Treatment and management for Fe2+ anaemia
Oral iron replacement OR
Parenteral iron replacement
Blood transfusion - serious cases with low haemoglobin
Ascorbic acid (helps in the absorption of iron)
Improve diet
Remember: Oral iron therapy, in appropriate doses and for a sufficient duration, is an effective first-line strategy for most patients.
Complications for Fe2+ anaemia
Diastolic heart failure
Impaired muscular performance
Cognitive impairment
Developmental delays
What do we need iron for?
Iron reacts with protoporphyrin (pigment in RBC) converts it to haem. Haem is essential for haemoglobin. Therefore less iron-less haem-less haemoglobin
What happens if there is less haemoglobin in the blood due to iron. Related condition
Iron deficiency (condition)
It takes up most volume in blood and therefore becomes Microcytic- decrease in MCV less than 80fl.
Iron-deficiency Anaemia and Children (Risk Factors)
Low birth weight
History of prematurity
Exposure to lead
Exclusive breastfeeding beyond four months of life
Weaning to whole milk and complementary foods without iron-fortified foods.
Although iron deficiency anemia is associated with cognitive delays in children, it is unclear if iron supplementation improves cognitive outcomes.
Syptoms Iron deficiency Anaemia and Children
Early symptoms: poor attention span, irritability
Later symptoms & signs: cognitive deficits, lethargy, pallor, poor growth, weakness, listlessness, dyspnoea/ tachypnoea, conjunctival pallor, tachycardia pica, poor feeding, cardiomegaly & signs of cardiac failure
What is thalassemia?
Genetic condition
Two types (alpha and beta)
Missing a globin chain:
alpha: 1aplha + 2beta
beta: 2alpha + 1beta
Where is thalassemia more common in?
Mediterranean ancestry
Thalassemia-microcytic or macrocytic?
microcytic
Treatment of thalassemia
Bone stem cell transplant
Iron
Transfusion
What is alpha thalassemia?
Autosomal recessive
Deletion of alpha globin genes on chromosme 16
No. of defective thalassemia
- Defective alpha gene: Silent carrier
- Defective alpha gene: Alpha thalassemia Minor = mild symptoms
- Defective alpha genes: Haemoglobin H (HbH) disease (excess Beta chains). Enlargens liver, spleen and bone containing bone marrow
- Alpha genes deleted: Hb Bart’s Hydrops foetal
Initial symptoms of alpha thalassemia
Diagnosis of alpha thalassemia
+Haemoglobin electrophoresis
Confirmed by: genetic testing
Treatment for alpha thalassemia
What is beta thalassemia
Autosomal recessive
Mutation in Beta globin gene on chromsome 11. This results in a reduced or absent Beta globin chain synthesis
3 types of beta thalassemia
Symtoms of beta thalassemia
Diagnosis of beta thalassemia
Confirmed : Haemoglobin electrophoresis. Low HbA, High HbF, HbA2
Treatment for beta thalassemia
What is sideroblastic anaemia
type of blood disorder where there’s a buildup of iron in the RBC’s in the body causing them to be immature and dysfunctional
Causes of sideroblastic anaemia
Congenital abnormality
Acquired cause:
-Vitamin B6 deficiency
-Excessive alcohol use
-Lead poisoning
=Decrease in functional haem -> damage to other organs -> anaemia and fatigue
Diagnosis of sideroblastic anaemia
Treatment for sideroblastic anaemia
Removal of Toxins
Pyridoxine, thiamine & folic acid
Macrocytic anaemia
Normocytic (MCV 80-95)
Haemolytic – Sickle cell, Hereditary spherocytosis, G6PDH deficiency, Malaria, Autoimmune Haemolytic
Non-Haemolytic – CKD, Aplastic
What is haemolytic anaemia
Anaemia due to premature destruction of red blood cells
Haemolysis cn occur either
Intravascularly: haemolysis occuring within vasculature
Extravascularly: haemolysis occuring outside vasculature, typically in organs such as spleen or liver
What does haemolysis stimulate the production of
Erythropoietin
What is the reticuloendothelial system
Clearence of old/damaged RBC
Classic laboratory result findings in Haemolytic anaemia
What causes intravascular haemolysis (COMMA)
1.Mechanical Valve (sheer stress) -> haemolysis
2.Microangiopathic haemolysis
3.Cold autoimmune haemolytic anaemia
4.Osmotic lysis following infusion of hypotonic solution
5.Acute transfusion reactions
What causes extravascular haemolysis
Further subdivided into extracorpuscular and intracorpuscular
What is sickle cell anaemia
Sickle cell anaemia is an autosomal recessive disorder causing production of abnormal ß-globin chains. A single amino acid is substituted in the ß-globin chain (Glu to Val at position 6). This results in the production of HbS (haemoglobin Sickle) rather than HbA. The common variants of sickle cell disease are:
Sickle cell anaemia (SS disease) is the most common
Sickle cell trait - causes no disability and protects from malaria except in hypoxia.
Sickle ß Thalassemia (HbS/ßthal)
Sickle haemoglobin C disease (HbSC)
What causes sickle cell anaemia
A missense mutation in the Beta Globin chain
When in sickle cell anaemia does haemoglobin have its sickle shape?
When its not bound to oxygen
What can sickle cell anaemia lead to?
Splenic infarction (<2yo)
Increase risk of infection
Failure to thrive
Chronic renal failure
Gallstone
Iron overload
Lung damage - Hypoxia → fibrosis → pulmonary hypertension
Aplastic crisis - Paravirus B19 infection causing drop haemotocrit
Remember Paravirus B19 infection causing drop haemotocrit in sickle cell and thalassaemia. Treatment is immunoglobulins
Treatment of sickle cell anaemia
Sickle cell anaemia can mean that your immune to what?
Malaria
Diagnosis of sickle cell anaemia
Sickle cell disease can be diagnosed in newborns, as well as older persons, by hemoglobin electrophoresis, isoelectric focusing, high-performance liquid chromatography or DNA analysis
FBC
Blood smear - sickle cells and target cells
Remember Sickle cell trait have normal blood smear, sickle cell anaemia does not!
Side note Target cells are found in Thalassaemia too.
Sickle solubility test
The parents of the affected child with sickle cell aneamia will show features of sickle cell trait.
Sickle solubility test is where a mixture of Hb S in a reducing solution such as sodium dithionite gives a turbid appearance because of precipitation of Hb S, whereas normal Hb gives a clear solution.
Differential diagnosis of sickle cell anaemia
Autoimmune haemolysis
Hereditary spherocytosis
G6PD deficiency
Signs and symptoms of sickle cell anameia
Overview Newborns are usually asymptomatic because babies still have fetal haemoglobin
Vaso-occlusive crisis
Dactylitis (children)
Mesenteric Ischaemia
CNS infarction - seziures, stroke, cognitive defects
Avascular necrosis (neck of femur)
Leg ulcers
Priapism
Fever - infection
Acute chest syndrome
a new infiltrate on chest x-ray
associated with one or more NEW symptoms:
fever, cough, sputum production, dyspnea, or hypoxia.
Acute splenic sequestration
Splenomegaly
Hepatomegaly
Aplastic crisis - due to parovirus infection, with a sudden reduction in bone marrow production
Remember children typically present with acute dactylitis. Males can present with priapism
Pathophysiology of sickle cell anaemia
Substituting one amino acid in the haemoglobin molecule results in sickle haemoglobin. Amino acid changed from Glu to Val. As a result, RBCs sickle in low oxygen states, causing occlusion of blood vessels, increased viscosity, and inflammation.
The average life span of these sickle RBCs is 20 days (120days is normal)
What is hereditary spherocytosis
Genetic
Mutation (ankyrin and spectrin) results in a spherical haemoglobin-loses its biconcave shape. Not good at delivering oxygen effectively as it gets stuck
Risk Factors of hereditary spherocytosis
Family History of anaemia of haemolysis
Northern European
Hereditary spherocytosis symptoms
Splenomegaly
Haemolysis
How to detect hereditary spherocytosis?
Lab: Coombs test
Clinically: Anaemia, jaundice, gall stones, splenomegaly
Treatment for hereditary spherocytosis
There is no cure for HS, but it can be treated. The severity of your symptoms will determine which course of treatment you receive. Options include:
Surgery: In moderate or severe diseases, removing the spleen can prevent common complications that result from hereditary spherocytosis. Your red blood cells will still have their spherical shape but live longer. Removing the spleen can also prevent gallstones.
Not everyone with this condition needs to have their spleen removed. Some mild cases can be treated without surgery. Your doctor might think less invasive measures are better suited for you. For example, surgery is not recommended for children younger than 5 years.
Vitamins: Folic acid, a B vitamin, is usually recommended for everyone with HS. It helps you make new red blood cells. A daily dose of oral folic acid is the main treatment option for young children and people with mild cases of HS.
Transfusion: You may need red blood cell transfusions for severe anaemia.
Light therapy: The doctor might use light therapy, also called phototherapy, for severe infant jaundice.
Vaccination: Getting routine and recommended vaccinations are also important to prevent infectious complications. Infections can trigger the destruction of red blood cells in people with HS.
What is G6PD deficiency
What triggers G6PD Deficiency
Infections
Food
Medications e.g Sulfa-drugs & antimarials
Symptoms of G6PD deficiency
Jaundice
Dark Urine
Back Pain
Anaemia
Typical Findings with someone having G6PD Deficiency
Blood Smear:
Heinz Bodies
Bite Cells
Diagnosis of G6PD Deficiency
Confirmed with Enzyme Assay
Treatment of G6PD Deficiency
Avoid Oxidant Factors
Transfusion (if haemolysis is SEVERE)
What is autoimmune haemolytic anaemia
A condition where the immune system makes antibodies against specific antigens on RBC.
Types of autoimmune haemolytic anaemia
Pathway by which RBC are destroyed
Aetiologies of Autoimmune haemolytic anaemia
Symptoms of autoimmune haemolytic anaemia
Diagnos of haemolytic autoimmune anaemia
Treatment for Autoimmune haemolytic anaemia
Warm: corticosteroids
Cold: Plasmapheresis
Aetiologies of Autoimmune haemolytic anaemia
Diagnos of haemolytic autoimmune anaemia
What is aplastic anaemia, what does it cause?
Form of pancytopenia resulting form the autoimmune destruction of haematopoirtic stem cells
Causes of Aplastic anaemia
Medications
Viruses
Toxins
Genetic Disorders
Treatment for aplastic anaemia
Stem cell transplant
Immunosuppressive therapy