erythrocytes and erythrocyte indices

Question 1

what is the first step that needs to be taken when assessing a blood sample and what information can be obtained from this?

Answer 1

centrifuge the blood sample to separate the plasma from the red blood cells. Can be used to obtain the Hb (haemoglobin concentration - 150g/L normal); RBC (red blood cell count - 5 X 1012/ L normal); and the HCT or PCV

Question 2

what is the Packed Cell volume (PCV)?

Answer 2

also known as the haematocrit (HTC) this is the volume of the red blood cells in the sample after centrifugation

Question 3

what is the Mean corpuscular volume (MCV) and how can it be measured?

Answer 3

The MCV is the average volume of one red blood cell. This can be calculated by:
volume of large number of red blood cells /number of RBCs
MCV=PCV/RBC = 90fl

Question 4

what is the normal range for MCV?

Answer 4

80-95fl

Question 5

what is the name for an MCV value lower than 80fl?

Answer 5

microcytic anaemia

Question 6

what is the name for an MCV value higher than 95fl?

Answer 6

macrocytic anaemia

Question 7

what is the mean corpuscular haemoglobin? (MCH)

Answer 7

The MCH is the average amount of haemoglobin in one red blood cell.

Question 8

How do you calculate the MCH?

Answer 8

amount of Haemoglobin in a large number of red blood cells/ number of RBCs
MCH=Hb/RBC

Question 9

what is the normal range for the MCH?

Answer 9

27-31pg

Question 10

what is the mean corpuscular haemoglobin concentration (MCHC)?

Answer 10

the average concentration of haemoglobin in one red blood cell

Question 11

How do you calculate the MCHC?

Answer 11

can be calculated of one RBC or large number of RBCs:

1. MCH (amount of Hb in one cell)/ volume of one cell (MCV)
2. Hb (amount of Hb in many cells)/PCV (volume of many RBCs)

Question 12

what is the normal value for haemoglobin (in large number of RBCs) for males and females?

Answer 12

male: 130 - 170 g/L
female: 115 - 160

Question 13

what is the normal value for red blood cell count in males and females?

Answer 13

males: 4.3 - 5.7 X 10 12/L
females: 3.9 - 5.1

Question 14

what is the normal value for HTC or PCV?

Answer 14

males: 0.39 - 0.5 l/l
females: 0.34 - 0.47

Question 15

what is anaemia?

Answer 15

anaemia is a reduction in haemoglobin or red blood cell concentration in the blood. Can result in a reduced supply of oxygen to the tissues (tissue hypoxia)

Question 16

what are some symptoms of anaemia?

Answer 16

fatigue, headaches, palpitations, weakness, breathlessness

Question 17

what are some signs of anaemia?

Answer 17

pallor in the face and under eyes; glossitis (inflamed tongue); angular stomatitis; and koilonychia (spoon shaped nails)

Question 18

what do platelets look like in histology?

Answer 18

very small (2-3 microns)

Question 19

what is the lifespan of platelets?

Answer 19

5-9 days

Question 20

where are old platelets destroyed?

Answer 20

in the spleen by phagocytosis of monocytes and in the liver by kupffer cells (also monocytes)

Question 21

how are platelets synthesised?

Answer 21

by megakaryocytes - these large cells form cytoplasmic dendrites with the microtubules and then bud off to form vesicles containing platelets. each one produces 5,000 - 10.000 platelets.

Question 22

what is a thrombosis and how is it formed?

Answer 22

a thrombosis is a clot formed in blood vessels by platelets. platelets aggregate to bridge the gap. fibrin (fibrous protein) is produced from fibrinogen to create a clot. vasoconstriction also takes place to limit haemorrhage.

Question 23

what is an embolus?

Answer 23

a thrombus that has broken off from the blood vessel wall. can block blood vessels. can also get trapped in the lungs (causing a pulmonary embolus) can be fatal.

Question 24

what is the normal Hb (haemoglobin concentration) of a sample?

Answer 24

150g/l

Question 25

what is the normal value for HCT/PCV (packed cell volume)?

Answer 25

0.45l/l