Anaemia

Question 1

Definition

Answer 1

Haemoglobin concentration falls below the defined level

Clinical consequence of insufficient O2 delivery

Question 2

Causes

Answer 2

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

Question 3

Symptoms

Answer 3

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

Question 4

Signs

Answer 4

Pallor - pale conjunctivae
Tachypnoea
Tachycardia

Question 5

Chronic anaemia

Answer 5

Loss of HB over months - can be relatively asymptomatic

Question 6

Causes (5)

Answer 6

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

Question 7

Classification

Answer 7

Size of RBC
Acute or chronic
Underlying aetiology

Question 8

Iron Deficiency

Answer 8

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

Question 9

Diagnostic tests for iron

Answer 9

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

Question 10

Causes of iron deficiency in UK

Answer 10

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

Question 11

Size of RBC

Answer 11

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)

Question 12

Blood film

Answer 12

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

Question 13

Reticulocyte count

Answer 13

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

Question 14

History when anaemia suspected

Answer 14

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

Question 15

Megaloblastic anaemia

Answer 15

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

Question 16

B12 deficiency

Answer 16

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

Question 17

Folate deficiency

Answer 17

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

Question 18

Anaemia of chronic disease

Answer 18

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

Question 19

Sickle cell anaemia

Answer 19

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

Question 20

Sickle cell anaemia mechanism

Answer 20

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

Question 21

Thalassaemia

Answer 21

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

Question 22

Bone Marrow infiltration

Answer 22

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

Question 23

Management of acute anaemia

Answer 23

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

Question 24

Management of chronic anaemia

Answer 24

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

Question 25

Worldwide impact

Answer 25

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