W1L1 - Approach to Anaemia

Question 1

Anaemia

Answer 1

Significant decrease in haemoglobin concentration

Often with concurrent decrease in RBC concentration and haematocrit

Question 2

Is anaemia a disease?

Answer 2

No, it is a clinical sign that reflects an underlying disorder/disease

Question 3

Diagnosis of Anaemia

Answer 3

1. Patient history
2. Physical examination
3. Laboratory testing
   - FBC
   - blood film assessment
   - reticulocyte count
   - bone marrow assessment
   - additional assays

Question 4

Anaemia Classification

Answer 4

Morphological
- classification using RBC characteristics determined by routine haematology methods
Functional
- classification by the pathophysiological mechanism that incited/resulted in the anaemia
Aetiological
- classification by the specific inciting cause of the anaemia

Question 5

Morphological Classification

Answer 5

Based on:
- characteristics of RBCs in blood films
- characteristics of RBC determined by automated haematology analysers
Assesses RBC:
1. Size: “- cytic”
2. Colour: “- chromic”
3. Shape: “- poikilo”
Laboratory values (RBC indices)
- MCV
- MCH, MCHC
Morphology alone is insufficient to determine aetiology

Question 6

What does morphological classification allow for?

Answer 6

Rational selection of further assays to determine aetiology
Efficient use of resources
Expedient investigation

Question 7

Functional Classification

Answer 7

Classification of anaemia by causative pathophysiological mechanism:

1. Proliferation defects
   - bone marrow disorders
2. Maturation defects
   - genetic
   - nutritional
3. Survival defects
   - loss (haemorrhage)
   - destruction (haemolysis)

Question 8

Proliferation Defects

Answer 8

Includes a range of disorders of erythropoiesis
- insufficient erythropoietin
- bone marrow damage
- stem cell damage
Results in decreased production of RBC
Morphology
- typically normocytic, normochromic
Aetiology: many
- renal disease
- lymphoma
- radiation, chemotherapy

Question 9

Maturation Defects

Answer 9

Abnormal nuclear or cytoplasmic development of RBC during erythropoiesis

Question 10

Maturation Defects - Nuclear Defects

Answer 10

Affect all cell lines (RBC, WBC, PLT)
Morphology
- macrocytic
- normochromic/hypochromic
Aetiology
- e.g. B12, folate deficiency

Question 11

Maturation Defects - Cytoplasmic Defects

Answer 11

Abnormal haemoglobin production
Morphology
- microcytic 
- hypochromic
Aetiology
- e.g. iron deficiency

Question 12

Survival Defects

Answer 12

Premature loss (haemorrhage) or destruction (haemolysis) of RBCs
Haemorrhage
- overwhelmed mechanisms of haemostasis
- deficient mechanisms of haemostasis
Haemolysis
- intravascular, extravascular
- inherited, acquired

Question 13

Reticulocytes Stain

Answer 13

Method is based on supravital dye staining with New Methylene Blue
After initial off-line exposure to the dye, the blood is processed using a dedicated reticulocyte “mode” and RBC are analysed in the optical flow cell by three angles of laser light
Colours:
- pink-red = RBCs
- dark blue = mature reticulocyte fraction
- light blue = immature reticulocyte fraction