1.4 Approach to Anaemia

Question 1

What are possible causes of microcytic/ hypochromic anaemia?

Answer 1

iron deficiency, thalassemia, ACD

Question 2

causes of normochromic/ normocytic anaemia?

Answer 2

acute blood, renal anaemia, marrow infiltration

Question 3

causes of macrocytic, high MC anaemia

Answer 3

B12/ folate deficiency, drugs, hypothyroidism, liver, drugs; reticulocytes

Question 4

RBC measurements
- Haemoglobin (Hb) – directly measured as the ____________________
- MCV (mean corpuscular volume) – individual RBC volumes are directly measured as individual red blood cells passes through an aperture as the degree of _________________________ across the aperture
o Average of RBC volumes
- RBC (red blood cell count) – directly measured as a fixed volume of blood is aspirated by the _____________ and the number of RBCs passing through an aperture is counted
- Haematocrit – % of blood volume made up by RBCs, derived from ______________
- MCH (mean corpuscular haemoglobin) – average amount of haemoglobin in a RBC, derived from _________________
- MCHC (mean corpuscular haemoglobin concentration) – average haemoglobin concentration of an RBC
o Derived from _________________ (which is derived from MCV and RBC)

Answer 4

amount of light absorbed at a particular wavelength;

interruption of an electrical field;

automated counter;

MCV and RBC;

Hb and RBC;

Hb and haematocrit

Question 5

Red cell distribution width (RDW) – frequency distribution of sizes of red blood cells in a person’s blood sample, a normal distribution

• Measure of the range of variation of RBC volume – variability as shown by standard deviations
• RDW is a measure of ___________ – increases with increasing _____________________
• Even if the standard deviation of red blood cells remain constant, RDW can increase due to microcytosis

Answer 5

anisocytosis;

variability of RBC sizes

Question 6

how to differentiate iron deficiency anaemia from thalassaemia trait based on

• MCV
• RDW-CV
• red cell count
• peripheral blood smear

Answer 6

iron deficiency anaemia

• MCV: decreased
• RDW- CV: increased
• red cell count: decreased (red cells with variable degrees of iron produced at different times, resulting in variable cell size; lifespan is 120 days)
• peripheral blood smear: hypochromic elliptocytes

Thalassaemia trait

• MCV: decreased
• RDW- CV: increased or normal (mildly increased because of low MCV which is the denominator in the equation)
• blood sphere: target cells (not specific)

Question 7

microspherocytes are seen in?

Answer 7

Immune haemolysis or hereditary spherocytosis: smaller cell with no central pallor, indicative of loss of bioconcave shape

Question 8

blister cells are seen in?

Answer 8

oxidative haemolysis in G6PD deficiency, oxidised areas of RBCs are removed by splenic macrophages

Question 9

schistocytes (fragmented cells) are seen in?

Answer 9

microangiopathic haemolytic anaemia (red cells squeezed through arterioles and small vessels that are partially blcoked by clots or other microscopic emboli)