BL6 mathsy Flashcards
What is the normal range of MCH?
27-32 pico
What is the normal range of MCHC?
30-35 g/100ml or 300-350 g/l
What is the normal range of MCV?
83-96 fl
What does MCH stand for?
Mean cell haemoglobin
the average amount of Hb in a RBC
What does MCHC stand for?
Mean cell haemoglobin concentration
What does MCV stand for?
Mean cell volume
How is MCH calculated?
Hb(g) per litre of blood
/
Number of RBC per litre of blood
How is MCHC calculated?
Hb(g) per 100ml of blood
/
PCV (packed cell volume) expressed in ml per 100ml blood
What is packed cell volume?
the volume of packed red blood cells (from haematocrit) divided by the total volume of the blood sample
What is the difference between MCH and MCHC
MCH tells you the haemoglobin present in one RBC, MCHC tells you the haemoglobin present in one RBC as well as including the volume of the average amount of plasma surrounding a RBC
1) What are the units of :
a) MCHC
b) MCH
c) MCV
a) g/100ml or g/l
b) MCH expressed in pg, where p = pico (10-12
c) MCV expressed in fl, where f = femto (10-15)
1) What does a red blood cell count tell you?
2) What experiment is used to find out this info.?
1) The no. of RBC per litre
2) haemocytometer
1) What does haemoglobin conc. tell you?
2) What experiment is used to find out this info.?
1) in grams the amount of haemoglobin per litre
2) spectrophotometer (remeber this one is the coloured molecule
1) What does PCV tell you?
2) What experiment is used to find out this info.?
1) same as haematocrit, tells you the proportion of RBC in blood
2) Carry out centrifusion of blood in a heparinised cappillary tube, the measure length of tube filled with fluid and length of tube filled with red fluid,
the do shorter length divided by bigger length
What does heparinised mean?
add heparin to (blood or a container about to be filled with blood) to prevent it from coagulating
What are the stages to calculating mean cell haemoglobin content:
1) units first change haematocrit value to match volume used in units of Hg conc.. Therefore if Hg is g per 100 ml, Haematocrit= 28 mlper 100 ml. The value 28 would be used in calculations
2) Insert into formula:
Hb (g) per 100ml blood/
PCV expressed in ml per 100ml blood
3) Carry out calculation and convert from grams per ml to grams per litre by multiplying by 1000. e.g.
MCHC = 7.5/28 g.ml-1 = 0.268 g.ml-1 = 268 g.l-1
THE UNITS ARE NOT g/100ml as cancel out in calculation
What do you already have when calculating mean cell CONCENTRATION:
1) The formula
MCV = Volume of RBCs per litre of blood (l.l-1) / RBC number per litre (l-1)
2) The value of RBC number per litre as this equals red blood cell count
B) 1) find volume of RBC per litre of blood= haematocrit,
2) Check units of 1, as it is per litre and not per 100 litre the value 0.28 is correct
3) Insert numbers into calculation:
0.28 (l.l-1) / 4x1012 (l-1) = 0.07 x 10-12 l
4) Convert to appropriate units i.e multiply by 10 to the power of 15, femto
e.g.: 0.07 x 10-12 l = 70 x 10-15 l = 70fl
MCH (mean cell haemoglobin CONTENT):
A) What values derived from experiments aren’t needed?
B) which are:
C) What are the stages of calculating
c) 1) Write out formula:
MCH = Hb concentration (g.l-1) / Red cell count (l-1)
2) Convert Hb conc from g/100ml to g/l by multiplying by 10 e.g. 7.5 g.100ml-1 or 75 g.l-1
3) Insert into formula:
MCH= 75/4x10^12= 18.75 x 10-12 g
4) convert answer into appropriate units i.e. pico multiply by 10 to the power 12e.g:
18.75 x 10-12 g = 18.75 pg
What values from experiments to find: 1) MCH 2)MCHC 3) MCV (include units)
1) Hb conc. (g/l) / red blood cell count (l^-1)
2) Hb conc. (g/100ml)/ haematocrit (ml/100ml)
3) haematocrit (l/l) / red blood cell count (l^-1)
For males give you the normal range values for:
1) PCV
2) RBC
3) Hb conc.
1) 0.4-0.54
2) 4.5-6.5 x1012 l^-1
3) 130-180 g/l
For females give you the normal range values for:
1) PCV
2) RBC
3) Hb conc.
1) 0.37-0.474.
2) 3.8-5.8 x1012 l^-1
3) 115-160 g/l-1
Other than gender, what can influence PCV, RBC, and haematocrit?
age and race have minor effects,
geographical location does however e.g some people live at high altitude (e.g. in the Andes) and can have adaptive physiological responses such as increased PCV.
1) Why do anaemias not caused by iron deficiency express themselves as iron deficiency?
2) Describe the conclusion about the RBC drawn from the results and the indices when iron deficiency is present?
1) Body attempts to make more RBCs due to anaemia e.g. caused by haemorrhage or greater demand e.g.pregnancy. There is not enough iron to make enough Hb. Therefore cells produced are both small and lack Hb.
2) RBCs are microcytic (MCV would be low)
RBCs are hypochromic (MCH would be low)
- In folate/vitamin B12 deficiency which indices would you expect to change, and why?
RBCs are macrocytic (MCV would be high)
MCH may also be high (cells are bigger!)
BUT MCHC may be normal (although more Hb present in a RBC, the RBC is bigger in volume, so Hb concentration may be near normal).
During haematopoiesis, the red blood cell precursor cells size increases but nuclseus doesn’t = asynchronous nucleus and cytoplasm. They are not able to divide properly (due to folate vitB12 deficiency slowing DNA synthesis) hence get bigger than they should.
