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Haematology and Immunology > Red Blood Cells > Flashcards

Red Blood Cells Flashcards

1
Q

What is anaemia

A

Reduction in red cells or their haemoglobin. Theres multiple aetiologies.

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2
Q

Red cell production in marrow.

A

Haemocytoblast - committed cell (proerythroblast)

Developmental - early erythroblast - late erythroblast - noroblast - reticulocyte - erythrocyte (no nucelus)

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3
Q

Substances required for red cell production

A

Metals: Iron, copper, cobalt, manganese
Vitamins: B12, folic acid, thiamine, Vit.B6, C,E
Amino acids
Hormones: Erythropoietin (made in the kidneys), GM-CSF, androgens, thyroxine, SCF

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4
Q

Red cell breakdown

A

Normal life span is 120 days. They are normally removed from the circulation and replaced. Magrophages of the reticuloendothelial system (liver and the spleen) breakdown. Globin is re-utlised. The haem is broken down into bilirubin and iron. It is then conjugated in the liver and comes out in the bile and stercobiligin in the stool.

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5
Q

The Red Blood Cell

A

Biconcave disk, larger surface area for gas transfer and is able to squeeze through small spaces. Contains membrane, enzymes, haemglobin.

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6
Q

Genetic defects in congenital anaemias

A

Red cell membane, metabolic pathways, haemoglobin. These reduce red cell survival and result in haemolysis. The carrier states are often silent (autosomal recessive).

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7
Q

Red cell membrane

A

Bilipid layer, intrinsic proteins that help maintain the structure of the cell. Skeletal proteins inside to keep the cell flexible.

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8
Q

Defects in red cell membrane.

A

Defects in skeletal protiens leading to increased cell destruction. Mutations in Ankyrin, band 3 and spectrin.

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9
Q

Hereditary Spherocytosis

A

Defects in structural protein resulting in red cells being spherical. These are then removed from circulation by spleen. Leads to anaemia. The most common are autosomal dominant.

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10
Q

Clinical presentation of Herediatry spherocytosis

A

Anaemia
Jaundice (neonatal)
Splenomegaly
Pigment gallstones (due to increased haemolysis and bilirubin)

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11
Q

Treatment of Hereditary Spherocytosis

A

Folic acid (increased requirement)
Transfusion (if severe)
Splenectomy (remove the site of production)

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12
Q

Other rare membrane disorders (for information, don’t need to know)

A 
Hereditary Elliptocytosis (ellipotcytes, look like rods) 
Hereditary Pyropoikilocytosis (cells look an utter mess) 
South East Asian Ovalocytosis
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13
Q

Red cell enzymes

A

Glycolysis (production of ADP provides energy for the cell)

Pentose Phosphate Shunt (Protects from oxidative damage)

GLUCOSE 6-PHOSPHATE DEHYDROGENASE

PYRUVATE KINASE

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14
Q

Glucose 6 Phosphate dehydrogenase

A

Protects red cell proteins (Haemoglobin) from oxidative damage
Produces NADPH - Vital for reduction of glutathione
Reduced glutathione scavenges and detoxifies reactive oxygen species

More likely to break down as a result

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15
Q

G6PD Deficiency

A

Commonest disease causing enzymopathy in the world
Results in the cells vulnerable to oxidative damage.

X-Linked

Bite cells
Blister cells under the microscope.

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16
Q

Clinical Presentation of G6PD deficiency

A 
Neonatal Jaundice
Splenomegaly
Pigment Gallstones
Intravascular haemolysis 
Haemoglobinuria

Only really when exposed to infection, acute illness, drugs etc do symptoms occur

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17
Q

Drugs precipitating Haemolysis in G6PD deficiency

A

Antimalarials
Antibacterials
Analgesics
Antihelminthics

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18
Q

Pyruvate Kinase Deficiency

A

Reduced ATP, increased 2,3-DPG, cells rigid.

Anaemia, jaundice, gallstones.

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19
Q

Function of haemoglobin

A

To carry oxygen and facilitate oxygen delivery to the tissues.

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20
Q

Bohr Effect

A

Acidosis
Hyperthermia
Hypercapnia

Haemoglobin give up oxygen

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21
Q

Normal Adult Haemoglobin

A

2 Alpha Chains (4 alpha chain genes)
2 Beta Chains (1 beta gene)

HbA (alphaalphabetabeta)

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22
Q

Haemoglobinopathies

A

Inherited abnormalities of haemoglobin syntesis.

Reduced or absent globin chain production (Thalassaemia)

Point Mutations leading to structurally abnormal globin chain (HbS Sickle Cell anaemia)

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23
Q

Inheritance of Haemoglobinopathies

A

Autosomal Recessive Inheritance.

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24
Q

Sickle Haemoglobin

A

2 alpha chains
2 abnormal sickle beta chains.

When it is deoxygenated it crystallises and changes the shape to become a rigid abnormally shaped cell.

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25
Q

Consequences of HbS Polymerisation in Sickle Cell dDisease

A

Red cell injury, cation loss, dehydration resulting in haemolysis of the red cells.

Endothelial activation
Promotion of inflammation
Coagulation activation
Dysregulation of vasomotor tone by vasodilator mediators (NO) ALL RESULTING in VASO-OCCLUSION

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26
Q

Sickle Cell Disease Clinical Presentation

A

Painful Vaso-Occlusive Crises (bone pain)

Chest crises

Stroke

Increased infection risk (hyposplenism due to autoinfarction)

Chronic haemolytic anaemia (gallstones, aplastic crisis)

Sequestration Crises (when blood pools in the liver or spleen resulting in redution in blood volume)

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27
Q

Sickle Cell Painful Crises

A

Severe pain which often requires Opiates (30 minutes of presentation), hydration, oxygen, consider antibiotics (crises triggered by infection)

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28
Q

Sickle Cell Chest Crises Presentation

A

Chest Pain
Fever
Worsening hypoxia
Infiltrates on CXRay

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29
Q

Chest Crises Treatment

A 
Respiratory support
Antibiotics
IV fluids
Analgesia
Transfusion - top up or exchange target HbS <30%.
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30
Q

Life long prophylaxis of Sickle Cell Disease

A

Vaccination
Penicillin prophylaxis
Folic Acid

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31
Q

Other management of Sickle Cell Disease

A

Blood transfusion

Hydroxycarbamide

Bone marrow transplantation

Gene Therapy

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32
Q

Thalassaemias

A

Reduced or absent globin chain production. Mutations or deletions in genes. Chain imbalance results in chronic haemolysis and anaemia.

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33
Q

Homoygous alpha zero thalassaemia (alpha0/alpha0)

A 
No alpha chains
Hydrops Fetalis (incompatible with life)
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34
Q

Thalassaemia Major

A

No beta chains

Transfusion dependent anaemia

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35
Q

Thalassaemia Minor

A

“trait” or carrier state

Hypochromic microcytic red cell indices

36
Q

Presentation of Beta Thalassaemia Major

A

Severe anaemia presenting at 3-6 months. There is an expansion of ineffective bone marrow, bony deformities (marrow expansion) splenomegaly, growth retardation

37
Q

Life expectancy of untreated Beta Thalassaemia Major

A

<10 years

38
Q

Treatment of Beta Thalassaemia Major

A

Chronic transfusion support - 4-6 weekly.

Normal growth and development but Iron Overloading, Iron collaters which remove the iron.

39
Q

Iron Chelation Therapy

A 
s/c desferrioxamine infusions (desferal)
Oral deferasirox (exjade)
40
Q

Rare Defects in Haem Synthesis

A

Defects in mitochondrial steps of Haem Synthesis resulting in sideroblastic anaemia. ALA Synthase mutations, X-linked.

41
Q

Factors influencing normal haemoglobin

A 
Age
Sex
Ethic Origin 
Time of day sample taken 
Time to analysis
42
Q

Haemoglobin Male 12-70

A

(140-180)

43
Q

Haemoglobin Male >70

A

116-156

44
Q

Haemoglobin Female 12-70

A

120-160

45
Q

Haemoglobin Female >70

A

108-143

46
Q

General features of anaemia

A 
Tiredness/Breathlessness 
Breathlessness
Swelling of Ankles (due to heart failure) 
Dizziness (hyperdynamic blood flow) 
Chest Pain (reduce cardiac blood flow)
47
Q

Red Cell Indices

A

Automated measurement of red cell size and haemoglobin content.

MCV = mean cell volume (cell size)

MCH = mean cell haemoglobin

48
Q

Descriptions of anaemia Hypochromic Microcytic

A

Small pale cells. Do serum ferritin (measure of the bodies iron stores). Commonest cause is iron deficiency.

49
Q

Descriptions of anaemia Normochromic Normocytic

A

Normal colour (haemoglobin normal) and normal size. Do reticulocyte count (tests bone marrow function)

50
Q

Descriptions of anaemia Macrocytic

A

Large cells. Do B12/folate and bone marrow tests (bone marrow infiltration). Deficiency in B12 or folate results in macrocytic anaemia.

51
Q

Serum Ferritin (Low)

A

Iron deficiency anaemia

52
Q

Serum Ferritin (normal or increased)

A

Thalassaemia (without iron deficiency but looks like iron deficiency anaemia under the microscope due to microcytic hypochromic cells)

Sideroblastic anaemia

53
Q

Iron Metabolism

A

Amount you absorb from the duodenum of the gut (bound to plasma protein transferrin) is secreted in urine, faeces, nails, hair and skin

Iron is recycled from bone marrow to haemoglobin to macrophages to plasma, in a cycle

54
Q

Iron is stored

A

In ferritin in the liver

55
Q

Ferroportin

A

Protein that allows Iron to be transferred from the duodenum to transferrin. Also need this to put into the hepatocytes and the bone marrow.

56
Q

Hepcidin

A

Control ferroportins action, preventing it working, prevention of absorption of iron when it is not needed.

Synthesised in the hepatocytes in response to inflammation.

57
Q

Commonest cause of Anaemia

A

Iron Deficient Anaemia

58
Q

Common history of iron deficient anaemia

A

Dyspepsia - GI bleeding, carcinoma of the colon, gastritis
Menorrhagia
Diet
Increased requirement (pregnancy)
Malabsorption - gastrectomy, coeliac disease

59
Q

Clinical Features of Iron Deficiency

A

Koilonychia
Atrophic tongue
Angular Chelitis

60
Q

Investigations of Iron Deficinecy Anaemia

A

endoscopy

Barium Studies

61
Q

Management of Iron Deficient Anaemia

A

Correct the cause with diet, ulcer therapy, surgery if bleeding

Iron (oral adequate)
Transfusion if severe.

62
Q

Increased Reticulocyte Count

A 
Blood Loss (acutely) 
Haemolysis
63
Q

Normal Reticulocyte Count

A

Secondary Anaemia

64
Q

Haemolytic Anaemia

A

This is accelerated red cell destruction, compensation by the bone marrow by producing reticulocytes.

65
Q

Intravascular Haemolysis

A

Red cells are destroyed in the circulation due to toxins or drugs, valve related.

66
Q

Congential Haemolytic Anaemia

A 
Hereditary spherocytosis (HS)
Enzyme deficiency (G6PD deficiency)
Haemoglobinopathy (HbSS)
67
Q

Acquired Haemolytic Anaemia

A

Autoimmune Haemolytic Anaemia (extravascular)

Mechanical (valve)
Severe infection
Drugs

68
Q

Direct Antiglobulin Test

A

Detects antibody or complement on the red cell membrane.

Reagent contains either
anti-human IgG
anti-complement

Reagent binds to antibodies on red cell surface and causes agglutination in vitro. Implies immune basis for haemolysis.

69
Q

Postive Direct Antiglobulin Test

A

Immune mediated haemolysis

70
Q

Warm Autoantibody

A

Autoimmune
Drugs
CLL

71
Q

Cold Autoantibody

A

CHAD
Infections (mycoplasma infections)
Lymphoma

72
Q

Alloantibody

A

Transfusion reaction, antibodies made after transfusions

73
Q

Immune Haemolysis Film

A

Spherocytes on the film

Agglutination in cold AIHA

74
Q

Antibody in autoimmune haemolytic anaemia (extravascular)

A

IgM

75
Q

Intravascular haemolysis blood film

A

Red cell fragments (schistocytes)

Results in free haemologin which is very toxic to the kidneys

76
Q

Evidence that the patient is haemolysing

A

FBC, reticulocyte count, blood film
Serum bilirubin (direct/indirect), LDH (due to increased haemolysis results in increased unconjugated haemoglobin)
Serum haptoglobin

77
Q

Deciding the mechanism of Haemolytic Anaemia

A

History and examination
Blood film
Direct Antiglobulin Test (Coombs’ test)
Urine for haemosiderin/urobilinogen

78
Q

Management of Haemolytic Anaemia

A

Folic acid (supports bone marrow function)

Correct the cause
Immunosuppression if autoimmune

Remove the site of red cell destruction

Consider transfusion

79
Q

Secondary Anaemia

A

Anaemia of chronic disease.

Mostly normochromic normocytic with increased ferrtin and hepcidin.

Treat underlying cause

80
Q

Megaloblastic Anaemia (B12/Folate Deficinecy)

A

Anaemia and neurological symptoms (unexplained neuropathy)

81
Q

Causes of B12 deficiency

A

Pernicious anaemia

Gastric/ileal disease

82
Q

Folate deficiency causes

A

Dietary
Increased requirements (haemolysis)
GI pathology

83
Q

Signs of megaloblastic anaemia

A

Lemon yellow tinge to the skin. Elevated Bilirubin and LDH.

Oval macrocytes of blood film

84
Q

Vitamin B12 Absorption

A 
Dietary B12 binds to intrinsic factor,
secreted by gastric parietal cells
B12-IF complex attaches to specific
IF receptors in distal ileum
Vitamin B12 bound by 
transcobalamin II in portal circulation
for transport to marrow and other
tissues
85
Q

Pernicious Anaemia

A

Autoimmune disease against intrinsic factors, resulting in malabsorption of vitamin B12.

86
Q

Treatment of Megaloblastic Anaemia

A

B12 deficiency by B12 IM loading dose then 3 monthly maintenance

Folate Deficiency oral folate replacement

87
Q

Other causes of Macrocytosis

A 
Alcohol
Drugs
 Methotrexate, Antiretrovirals, 
 hydroxycarbamide
 Disordered liver function
 Hypothyroidism
 Myelodysplasia

Haematology and Immunology (20 decks)

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