Anaemia Flashcards Preview

Module 103: Theme 2 > Anaemia > Flashcards

Flashcards in Anaemia Deck (25):
1

Definition

Haemoglobin concentration falls below the defined level
Clinical consequence of insufficient O2 delivery

2

Causes

Low RBC count
Low HB content
Altered HB doesn't carry sufficient oxygen

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Symptoms

Lethargy - low supply of blood to tissues
Shortness of breath
Palpitations - pulsing blood in ears
Headache

Often non-specific
Worse if acute onset
Loss of blood over short amount of time like haemorrhage is anaemia due to hypovolemia and loss of HB

4

Signs

Pallor - pale conjunctivae
Tachypnoea
Tachycardia

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Chronic anaemia

Loss of HB over months - can be relatively asymptomatic

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Causes (5)

Bleeding over many months

Deficiency in necessary components: in iron, B12, folic acid - components needed to make DNA. deficiency from diet or reabsorption from gut - anaemia due to lack of synthesis of RBC

Haemolytic: increased RBC destruction, shortened RBC lifespan, RBC consumed at a faster rate than being produced - also cause of sickle cell where more RBC in bone marrow than normal known as compensation

Bone Marrow Dysfunction/Infiltration: e.g. aplastic anaemia

Poor O2 utilisation/carriage

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Classification

Size of RBC
Acute or chronic
Underlying aetiology

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Iron Deficiency

Most common type

Range of causes: bleeding, nutrition, increased requirements, bowel cancer, Pectacarcaration in oesophagus, Crohn's disease (malabsorption), pregnancy

Ferritin binds iron in tis core - find in liver and bone marrow where it holds iron and releases it to be incorporated in red cells, iron is needed for enzymatic processes in body - test ferritin for iron deficiency

9

Diagnostic tests for iron

Serum ferritin: Storage form of iron, low = deficient

Serum iron: Labile so reflects recent intake of iron - not very useful

Serum transferrin: Carrier molecule for iron, goes up if iron deficient, picks up iron in gut and carries to tissues, if iron deficient then high transferrin to take more from gut to get to tissues

Percent transferrin saturation: sensitive measure of iron status, low means deficient

10

Causes of iron deficiency in UK

Bleeding: menstrual heavy periods (menorrhagia), Occult GI malignancy - loss of blood in stool (indicative of bowel cancer), GI peptic ulceration

Unlikely to be iron deficient from diet alone but vegans at higher risk, malabsorption from coeliac disease and Crohn's

Increased requirements - from pregnancy

11

Size of RBC

Mean corpuscular volume - normally 80-100fL
Microcytic (small) - iron deficiency, inherited disorders of HB (thalassaemia)
Macrocytic (large) - B12 and folic acid deficiency, myelodysplasia
Normocytic (normal)

12

Blood film

Easy, quick, useful for haematinic deficiency, haemolysis, normal white cells
RBC last 100 days in the circulation
Features: Hypochromia, microcytosis, pencil cells, target cells

13

Reticulocyte count

Represents RBC production rate by marrow: low if bone marrow infiltrated, low during iron deficiencies, high in haemolysis, high in chronic bleeding, if in normal range when anaemic, bone marrow is not responding appropriately
Can be used to monitor progress of treatment
Measured by flow cytometry that counts cells with nucleic acids or using a specific statin and microscopy

14

History when anaemia suspected

GI symptoms: dyspepsia, change in bowel habit, weight loss
Menstrual history
Dietary history, travel (hookworm infestations cause iron deficiency), ethnic origin, family history

15

Megaloblastic anaemia

Macrocytic
Due to deficiency of vit B12, folate
Required for DNA
Large RBCs, sufficient precursors for cell growth, insufficient precursors for cell division

16

B12 deficiency

Dietary - strict vegans
Pernicious anaemia: autoimmune (parietal cell loss), deficiency of intrinsic factor (they can't absorb B12)
Malabsorption: Post gastric/ surgery
Crohn's disease

17

Folate deficiency

Dietary
Malabsorption (Coeliac, Crohn's disease)
Excess utilisation (Chronic haemolysis, pregnancy)
Alcohol
Drugs (phenytoin, methotrexate)

18

Anaemia of chronic disease

Most common form of anaemia in hospitalised patients

Common causes: Chronic inflammation, chronic infection (TB), Auto-immune conditions (rheumatoid arthritis), cancer

Poor utilisation of iron in body: iron is stuck in macrophages of the reticuloendothelial system and can't be mobilised into the early erythroblasts

Dysregulation of iron homeostasis: decreased transferrin, increased hepcidin


Impaired proliferation of erythroid progenitors: blunted response to erythropoietin, iron is unavailable

19

Sickle cell anaemia

Point mutation in beta globin gene causing HbS

RBC turnover = 20 days
due to haemolysis

Sickle cell crisis: Triggered by low blood O2 level, vaso-occlusive, ischaemia, pain, necrosis and often organ damage

Management: analgesics, hydration, transfusion

Genetic, autosomal, recessive, sub-Saharan Africa, shortened life expectancy

20

Sickle cell anaemia mechanism

Mutated sickle haemoglobin
Forms long filamentous strands
Insoluble at low O2 tension
RBCs become inflexible + spiky - problem

Sickle cell trait = heterozygous for HbS and HbA, much lower risk of sickling and crisis
Resistant to malaria infection

21

Thalassaemia

Insufficient Hb production - due to altered Hb gene expression
Inherited autosomal recessive
Clinical features: enlarged spleen, liver and heart; bones may be misshapen

Ask about family history
Conduct a blood film

22

Bone Marrow infiltration

Leukaemia: non specific symptoms, bone marrow failure
Lymphoma: lymphadenopathy, weight loss
Myeloma: anaemia, hypercalcaemia, renal failure

Get bone marrow from iliac crest - aspirate film for morphology of cells, trephine biopsy for histological sections

23

Management of acute anaemia

Transfuse: Acute is more dangerous that chronic, guided by symptoms instead of Hb levels

24

Management of chronic anaemia

Treat underlying cause: iron supplementation, folic acid and B12
Erythropoietin in patients with kidney failure particularly of on haemodialysis
Long term transfusion causes: iron overload, allo-antibodies

25

Worldwide impact

Poor pregnancy outcome
Impaired physical and cognitive development
Increased risk of morbidity in children
Reduced work productivity
contributes to 20% of all maternal deaths