28 - Haematology - Blood and Anaemia Flashcards
-paenia
Not enough
Too many red cells
Polycythaemia
Too many white cells in blood
Leukocytosis
Too many platelets in blood
Thrombocytosis
Red cells not functioning properly
Dyserythropoiesis
White cells not functioning properly
White cell function defect
Platelets not functioning properly
Platelet function defect
How is anaemia measured?
By measuring haemoglobin, not red cells
How is anaemia defined?
Hb count below what is normal for age and gender
Most important equation in haematology
Tissue oxygen delivery
Cardiac output x [Hb] x % saturation of Hb x 1.34
L/min x g/L x mL/g x 1.34 = mL/minute
Clinical signs of anaemia 1) 2) 3) 4) 5) 6)
1) Pale
2) Lethargic
3) Failure to thrive (in children)
4) Hypoxia
5) Ischaemia
6) Tachycardia
Important factor to consider when deciding whether to give a blood transfusion
Cardiac compensation. If heart rate is very high, then transfuse quickly, as can’t sustain very high heart rate for long
Why don’t you ventilate anaemics with O2?
Saturation of Hb is already high, there just isn’t enough Hb
Normal amount of Hb in blood
120-140g/L
Thing to be careful of when reading Hb content of blood result
Whether the lab measures Hb per L or per decilitre (will make normal either 120-140 or 12-14)
Full blood examinations 1) 2) 3) 4) 5) 6) 7) 8) 9) 10)
1) Hb
2) Red cell count (RCC)
3) Haematocrit (Hct)
4) Mean corpuscular volume (MCV)
5) Mean corpuscular haemoglobin (MCH)
6) Mean corpuscular haemoglobin concentration (MCHC)
7) Red cell distribution width (RCDW)
8) Platelet count
9) White cell count
10) Blood film
RCC
Red cell count.
Measures red cell concentration in blood.
Normal is 4.5-5x10^12/L
Hct
Haematocrit.
Analyses proportion of blood that is cellular.
MCV
Mean corpuscular volume
Flow cytometry of RBC.
Gets mean size of RBC
MCH
Mean corpuscular haemoglobin
Dissolve RBCs, only leaving Hb. Measure amount of Hb, average it for number of dissolved RBCs
RCDW
Red cell distribution width
Distribution of RBC size around MCV
Blood film
Observe blood under a microscope and examine cell morphology
Two broad types of anaemia
Regenerative and non-regenerative
More dangerous type of anaemia
Regenerative. Indicates that something is killing blood cells once they have been made (bone marrow is working properly). Can very quickly drop [RBC]
Signs of increased blood cell production
Reticulocytes, polychromasia (from immature Hb)
Signs of increased blood cell destruction
1)
2)
3)
1) Jaundice (increased serum bilirubin)
2) Haptoglobins (pick up extracellular Hb)
3) Lactate dehydrogenase (pick up extracellular Hb)
Amount of blood in neonates
~80mL/Kg weight
How often are red cells replaced?
~120 days
White cell normal blood concentration
2-6 x 10^9/L
How often are white cels replaced?
Every 3-5 days
Normal platelet concentration
150-400 x 10^9
How often are platelets replaced?
Every 10 days
Basic causes of anaemia
1)
2)
3)
1) Failure of production
2) Increased destruction/loss
3) Inappropriate production
Classifications of anaemia 1) 2) 3) 4) 5)
1) Regenerative
2) Non-regenerative
3) Microcytic
4) Normocytic
5) Macrocytic
What can compensate for bone marrow problems with haematopoiesis?
Liver and spleen can begin making blood cells again.
Results in enlarged liver and spleen
Proportion of haematopoietic marrow that is fat
~50% fat spaces
Cell giving rise to blood cells
Pluripotent stem cell (haematopoietic stem cell)
How are pluripotent stem cells in bone marrow identified?
They can’t be ID’d yet
How are blood cells retained in bone marrow when there is blood flowing through it?
They express different adhesion molecules at different stages of development. EG: when RBCs are fully developed, they stop expressing adhesion molecules
Examples of haemopoietic growth factors
GM-CSF, thrombopoietin, erythropoietin
Most common reason for adult iron deficiency
Bleeding (EG: in gut)
Most common childhood reason for iron deficiency
Diet problem
Role iron plays in blood function
Haemoglobin function
Vitamin B12 function in blood
Important in development of all cells
Where does red marrow retract to from childhood to adulthood?
To axial skeleton
