Haem Flashcards
Signs / Symptoms Anaemia
Fatigue
Dyspnoea
Faintness
Palpitations
Headache
Tinnitus
Anorexia
Pallor
Hyperdynamic circulation e.g. tachycardia, flow mumurs, cardiac enlargement
Big consequences of anaemia
↓O2 Transport
Tissue hypoxia
Compensatory changes - (↑tissue perfusion, ↑O2 transfer to tissue, ↑RBC production)
Pathological consequences of anaemia
Myocardial fatty change
Fatty change in liver
Aggravate angina
Skin and nail atrophic changes
CNS cell death (cortex and basal ganglia)
State causes of macrocytic anaemia
B12/Folate def
+ HLARD
Hypothyroidism
Liver disease
Alcohol
Reticulocytes - haemolysis
Drugs - Azathioprine
State causes of normocytic anaemia
- Acute blood loss!
- Anaemia of Chronic disease
- BM failure
- Renal failure
- Hypothyroidism
- Haemolysis
- Pregnancy
Is haemolytic anaemia microcytic or macrocytic?
Neither - bc it can be normocytic or macrocytic
Define anaemia
State values
Low haemoglobin conc
< 135 g/L for men
< 115g/L for women
Investigations for anaemia
FBC + film
Reticulocyte count
U&Es, LFTs, TSH
Iron def - ferritin, iron studies, look for cause
Chronic disease - clinical Ix, lab investigation, renal failure?
B12 def - IF antibodies, schilling test, coeliac ab
Define FBC
What does one consist of?
Basic blood test that gives info on blood constituents
RBC vol
WBC vol (all types)
Platelet vol
Haemoglobin conc
Mean corpuscular volume (MCV)
Why is the GS Ix for IDA limited?
Because ferritin is an acute phase protein
What does reticulocyte count show?
How quickly new RBCs are being formed
What are reticulocytes?
Immature RBCs
What does a low reticulocyte count show?
Give an example of a cause
Something is preventing new RBCs from being produced
e.g. Haemantinic deficiency
What does a high reticulocyte show?
Give an example of a cause
RBCs are being lost or destroyed & ↑Reticulocyte as a compensatory mechanism
e.g. Bleeding or Haemolytic anaemia
What is ferritin?
Major iron storage protein of the body
What can ferritin be used to measure?
Used to indirectly measure iron levels in body
When and why can ferritin be falsely raised?
In inflammation and malignancy
Because it is an acute phase protein
What does a thick blood film permit?
Examination of a large amount of blood for presence of parasites (NOT identification of species)
What does a thin blood film permit?
Observation of RBC morphology, inclusions and intracellular/extracellular parasites
What does each haemoglobin molecule consist of?
2 alpha and beta chains
State the value ranges for micro, normo and macrocytic anaemia
MCV < 80 = Microcytic
MCV 80 - 100 = Normocytic
MCV > 100 = Macrocytic
UNITS - femtolitres 2
Where is iron absorbed?
Duodenum
Pathophysiology of Iron-Def anaemia
↓Iron available for haem synthesis
∴ ↓ Haemoglobin
∴ ↓ Effective RBCs
∴ Anaemia
Causes IDA
Low iron diet
Blood loss - menorrhagia, GI bleeding, Hookworm
Malabsorption - coeliac disease
Pregnancy
Breastfeeding
Signs/Symptoms more specific to IDA
Brittle hair and nails
Atrophic glossitis
Angular stomatitis
Koilonychia
DDx IDA
Anaemia of chronic disease
Thalassaemia
Ix IDA
FBC & Blood film - hypochromic microcytic RBCs
Also, anisocytosis and poikilocytosis
Serum ferritin - low
↑ Total iron binding capacity
↓Reticulocyte count
Endoscopy/Colonoscopy - to see if upper/lower GI bleed
Tx IDA
Treat cause!
Ferrous sulphate - oral iron
Ferrous fumarate
Continue for 3 months until Hb is normal
If a patient is responding to iron treatment, what should you find?
An increase in reticulocyte count
then gradual increase in Hb until normal
S/E of ferrous sulphate / fumarate
Black stool (melaena) ! (DDx for upper Gi bleed)
Constipation
Diarrhoea
Nausea
GI upset
Epigastric abdo pain
Microcytic Anaemia Causes
TAILS
Thalassaemia
Anaemia of Chronic Disease
Iron def
Lead poisoning
Sideroblastic anaemia
What is Plummer Vinson Syndrome?
TRIAD OF :
1. Dysphagia
2. Iron def
3. Oesophageal webs
What is Thalassaemia?
Inherited disease
↓ Rate of production or NO production
of one or more globin chains (α or β̞)
in red cell precursors OR mature RBCs
∴ in red cell precursors = ineffective erythropoiesis
& in mature RBCs = haemolysis
∴ ↓Production and ↑premature destruction of RBCs
Where is Thalassaemia most common?
Mediterranean
Middle East
Asia
How is Thalassaemia inherited?
Autosomal recessive
Types of Thalassaemia
α-Thalassaemia
β̞-Thalassaemia
What globin chains are found in the majority of adult haemoglobin?
2x alpha globin chains
2x beta globin chains
Where the gene for alpha-globin chains found?
On both chromosome 16s
Cause Alpha Thalassaemia
Gene deletions
How does alpha Thalassaemia present with 1 gene deletion?
(-a/aa)
Usually normal blood picute
Asymptomatic
How does alpha Thalassaemia present with 2 gene deletions?
(–/aa)
Asymptomatic with possible mild microcytic anaemia
Carrier for alpha thalassaemia
How does alpha Thalassaemia present with 3 gene deletions?
(–/-a)
Common in parts of Asia!
↓↓ Reduction of alpha chain synthesis ∴ HbH disease
Severe haemolytic anaemia & features of haemolysis = splenomegaly, jaundice, leg ulcers
Sometimes transfusion dependent
How does alpha Thalassaemia present with 4 gene deletions?
(–/–)
NO a-chain synthesis
Only Hb Barts present - not compatible w life bc cannot carry oxygen
Death in utero
Infants stillborn - pale, oedematous with huge livers and spleen
What chains does Hb Barts have?
4x gamma chains
Not compatible with life!
What is an evolutionary advantage of carriers of alpha thalassaemia?
Protected from falciparum malaria
Cause of B Thalassaemia?
Point mutation causing - transcription, RNA splicing and translation mutations
∴ Unstable and unusable B chains
Pathophysiology B Thalassaemia
Genetic defects
∴ little/no normal B chain production
∴ XS a chain production
∴ a-chains combine with whatever is available - B, gamma or delta chains
∴ ↑ Production of HbA2 and HbF
∴ Result in ineffective erythropoiesis and haemolysis
What chains does HbA contain?
2 alpha
2 beta
What chains does HbA2 contain?
2 alpha
2 delta
What chains does HbF contain?
2 alpha
2 gamma
Where are B-globin genes found?
Chromosome 11
What mutations occur in B-Thalassaemia?
Point mutations ?
Describe how B-Thalassaemia minor presents
Asymptomatic
Carrier state
Mild micro and hypochromic anaemia
Iron stores and ferritin normal
Describe how B-Thalassaemia intermedia presents
Moderate anaemia - Patients don’t require transfusion
Splenomegaly, bone abnormalities, recurrent leg ulcers & gallstones
Describe how B-Thalassaemia major presents
Presents in 1st year of life - Cooley’s anaemia (severe) - with :
Failure to thrive
Recurrent infections
Listless (lacks energy)
Crying
Pale
Bony abnormalities (bc hypertrophy of ineffective BM) e.g. skull bossing, thalassaemic faces w enlarged maxilla + prominent frontal and parietal bones, hair on end sign on skull XR
Hepatosplenomegaly (bc haemolysis)
Will require lifelong transfusion if develop to adulthood
Ix B-Thalassaemia
Blood film - microcytic hypochromic anaemia
Target cells visible!
Increased reticulocytes and nucleated RBCs in periph circulation
GS!! Hb electropheresis! - shows ↑ HbF and absent/low HbA
Skull XR - hair on end sign, enlarged maxilla
Tx B-Thalassaemia
Blood transfusions regularly (~2-4x per week)
HbA has time to replenish
Long term folic acid supplements
Histocompatible marrow transplant could cure!!
nB - risk of iron overload!!
∴ give iron chelation (SC desderrioxamine, oral deferiprone) to decrease iron loading
& Ascorbic acid to ↑urinary excretion of iron
–
Things to consider : bone health, endo supplements, psych support
Why is there a risk of iron overload with blood transfusions?
Repeat transfusions = deposition of iron in major organs
e.g. *liver, spleen (cirrhosis and fibrosis)
pancreas, heart and endocrine glands (DM, HF, premature death)
What should be monitored in a patient with B-Thalassaemia?
Why?
Ferritin
Cardiac & liver MRI
Endo testing - gonadal function, DM screening, growth and puberty
–
bc blood transfusions can lead to complications in major organs
What is sideroblastic anaemia?
BM produces ringed sideroblasts instead of healthy RBCs
Causes Sideroblastic anaemia
Congenital - rare, X-linked
Chemotherapy
Anti-TB drugs
XS alcohol
Ix Sideroblastic anaemia
Increased ferritin
Blood film - hypochromic RBCs
GS!! - Sideroblasts in BM
Tx Sideroblastic anaemia
Remove cause
Pyridoxine
Repeated transfusions for severe anaemia
(& ∴ iron chelation and ascorbic acid)
3 Main Causes Normocytic anaemia
- Acute blood loss
- Combined haematinic def e.g. iron and B12 def - balances out micro and macro
- Anaemia of chronic disease
Causes Anaemia of Chronic disease
*Crohn’s
*RA
TB
SLE
Malignancy
CKD
Ix Anaemia of Chronic disease
FBC and blood film - normocytic/microcytic and hypochromic
Low serum iron
Low total iron binding capacity (TIBC)
↑ or normal serum ferritin
Tx Anaemia of Chronic disease
Treat underlying cause
Recombinant erythropoietin
What 2 groups can macrocytic anaemia be divided into?
Megaloblastic
Non-Megaloblastic
What is a megaloblast?
When does one form? Why?
Cell where nuclear maturation is delayed but cytoplasm is not
∴ Lots of cytoplasm, tiny nucleus
Forms with B12 and folate deficiency
Bc both are required for DNA synthesis
What is a non-megaloblast?
When does one form?
Not a megaloblast
XS alcohol, reticulocytosis, liver disease, hypothyroidism
Other than causes for megaloblastic and non-megaloblastic, what are some causes for macrocytic anaemia?
Myelodysplasia
Myeloma
Myeloproliferative disorderes
Aplastic anaemia
What is folate found in?
Green vegetables, nuts, yeast and liver
What is folate synthesised by?
Gut bacteria
What is folate essential for?
DNA synthesis
Where is folate absorbed?
Jejunum
What does maternal folate deficiency cause?
Foetal neural tube defects
Causes of Folate Deficiency
Poor diet e.g. poverty, alcoholics, elderly
↑ Demand e.g. pregnancy or ↑cell turnover
Malabsorption e.g. coeliac disease, Crohn’s
Alcohol
Drugs - anti-epileptics, methotrexate
Ix Folate Deficiency
Blood film - anisocytosis and poikilocytosis w/ large oval macrocytes
Serum & red cell folate assay
Tx Folate Def
Assess for underlying cause (poor diet, malabsorption etc)
Folic acid (5mg/day PO for 4 months)
Prophylaxis for folate deficiency if pregnant
What does it prevent?
400mcg/day are given until 12 weeks
Helps prevent spina bifida
What is pernicious anaemia?
Autoimmune condition
Parietal cells are attacked
∴ atrophic gastritis AND ↓IF production
∴ ↓ B12 absorbed by iluem
Causes B12 Def
Diet - vegans
Pernicious Anaemia
Atrophic Gastritis
Malabsorption - Crohn’s, coeliac etc
Gastrectomy
Congenital metabolic errors
Basically anything that affects IF production by parietal cells in stomach
OR
anything that affects absorption in ileum
Where is B12 absorbed?
Terminal ileum
Bound to intrinsic factor (IF)
What produces B12?
Parietal cells
Signs / Symptoms Pernicious anaemia
Normal anaemia ones
+
Jaundice - XS breakdown of Hb
Neurological Sx - Polyneuropathy
Tongue Sx
Lemon yellow tinge
What is polyneuropathy caused by?
(Specifically relating to pernicious anaemia)
Symmetrical damage to peripheral nerves and posterior + lateral columns of spinal cord
How can you differentiate between B12 and folate deficiency?
Folate def does not have neuropathy but B12 does!
B12 and folate deficiency anaemias are what type of anaemia?
Megaloblastic macrocytic
Why are B12 and folate deficiency anaemia megaloblastic?
B12 and folate help with DNA synthesis
∴ deficiency = less DNA synthesis
∴ little nucleus + lots of cytoplasm
Ix Pernicious anaemia
FBC - ↓ Hb, ↑ MCV obvs
If severe, ↓WBC + platelets
Blood film - macrocytic RBCs
Megaloblasts in BM
Maybe ↓ Reticulocytes - production impaired
↓ Serum B12
MORE SPECIFIC TESTS :
Autoantibody screen for IF and parietal cells (present in 50% and 90% of cases respectively)
Tx Pernicious anaemia
Vitamin B12 (hydroxocobalamin) IM injections
NOT EVER FOLIC ACID !! - will cause fulminant neuro deficits
Comps Pernicious anaemia
HF
Angina
Neuropathy
A carrier of sickle cell disease (heterozygous) is protected from?
Falciparum malaria!
What is sickle cell disease?
Autosomal recessive normocytic haemolytic disease
Where is sickle cell disease more common?
In Afro-Caribbean ethnicities
Pathophysiology Sickle Cell disease
B globin gene mutation (glutamic -> valine)
∴ HbS variant is formed
When ↓O2, Hb variant polymerises and forms rod-like aggregates
∴ RBC becomes sickle-shaped + rigid
What triggers RBCs to turn sickle-shaped in sickle cell anaemia?
“Stress” e.g.
Cold
Infection
Dehydration
Hypoxia
Acidosis
Causes microvascular occlusion
Signs / Symptoms Sickle Cell disease
Can be Asx
Anaemia symptoms
Acute pain in hands + feet (dactylitis)
Jaundice (breakdown of Hb)
Ix Sickle cell anaemia
FBC - Normocytic normochromic with ↑reticulocyte count
Blood film - sickled erythrocytes
Howell-Jolly bodies
Hb electrophoresis
If 90% of Hb = HbS, then diagnostic!
–
NEONATAL SCREENING
Tx Sickle Cell disease
ACUTE ATTACKS :
IV fluid + Analgesia + O2
LONG TERM :
Avoid precipitants
Hydroxycarbamide + Folic acid supps
Transfusion (+ Iron chelation + Ascorbic acid)
What is the most common cause of death in adults with Sickle cell disease?
Pulmonary HTN
Chronic lung disease
Comps Sickle cell disease
Splenic sequestration - autosplenectomy !
Vaso-occlusive crisis
Osteomyelitis (In sickle cell patients, caused by salmonella!!!)
ACUTE CHEST CRISIS = pulmonary vessel vaso-occlusion!! can cause resp distress!!! EMERGENCY!!!
Type of haemolysis in Sickle Cell Anaemia
BOTH - Intravascular (inside vessels) && Extravascular (inside spleen)
How is spherocytosis inherited?
Autosomal dominant
Pathophysiology spherocytosis
↓ Spectrin
∴ ↑ RBC membrane permeability to Na+
∴ RBCs become rigid and spherical
∴ Spleen believes RBCs are damaged are they are prematurely destroyed
= Extravascular haemolysis
Signs / Symptoms Spherocytosis
General anaemia
NEONATAL JAUNDICE
Splenomegaly
Gallstones!
Ix Spherocytosis
FBC & reticulocyte count - ↑↑Reticulocytes!
Blood film - shows spherocytes
Osmotic fragility tests - RBCs fragile in hypotonic solution
Coombs’ test! (Direct anti-globulin test) = NEG !!
Rules out autoimmune haemolytic anaemia! (spherocytes are often seen in AHA)
What is the most common cause of spherocytosis or elliptocytosis ?
↓ Spectrin