LabD 5 RBC Flashcards
Main function?
Oxygen transportation
Problem with RBC causes?
Hypoxia in tissues
What can cause disease of RBC?
Transitions in RBC metabolism, many diff substances is produced. Transitional products
Most important RBC parameters?
RBC count, haemoglobin conc. and or function
RBC count, haemoglobin conc. and or function, these parameters can help us evaluate?
Polycytaemias and anaemias caused by diff external and internal causative agent
Haemoglobin measurement; spectrophotometric method (Drabkin method) how?
- Whole blood sample to reagent (potassium ferricyanide) which hemolyses RBCs and forms Fe3+ from Fe2+ in the haemoglobin molecule -> further oxidized by potassiumcyanide to cyanidmethaemoglobin
- Mix it and measure orange color enproduct by spectrophotometer
- Use standard solutions or standard curve to compare
Spectrophotometer method (Drabkin method) formula
Esample/Estandard x standard concentration = result (in same unit as standard) (E = extinction)
Normal value of haemoglobin in blood
18-20 mmol/L or 12-18 g/dl (g%)
Drabkin method; hemolyzed RBCs contains almost the whole amount of haemoglobin in blood, but what and where about the rest?
- Very small amount of free Hb, bound to carrier protein Haptoglobin (acute phase protein from last lab)
- Therefore no notable increase in Hb conc in case of intravascular hemolysis
Oxygen dissociation curve, left and right shift means?
- Left: decresed temp, decreased 2-3 DPG, decreased H+ conc, CO (increased affinity?)
- Right: reduced affinity, increased temp, increased 2-3 DPG, increased H+ conc
Oxygen binding capacity of Hb is increased by?
- Decreased 2,3 DPG level in RBCs
- Decreased pCO2 level in blood (ex. resp alkalosis)
- Decreased temp of blood (hypothermia)
- Increased pH of the blood (alkalosis, metabolic or resp)
Oxygen binding capacity of Hb is decreased by?
- Increased 2,3 DPG level in RBCs
- Increased pCO2 level in blood ( ex. resp acidosis)
- Increased temp of blood (hyperthermia)
- Decreased pH of blood (acidosis, respiratory or resp)
What is oxygen saturation?
Percentage (proportion) of oxygenated Hb molecules compared to the whole amount of Hb molecules in one unit of blood
Normal oxygen saturation values?
Arterial: 95-99%
Venous: 80-90%
Causes of increased Hb conc?
- Usually associated with different types of relative (dehydration) or absolute polycytaemia
Causes of decreased Hb conc?
- Usually associated with relative (hyperhydration) or absolute oligocytaemia
Is Hb conc affected by age of animals?
- Usually not, except swine: young pigs have much lower -Hb conc than older ones
Methaemoglobin?
- Hemoglobin containing Fe3+ –> unable to carry oxygen
- Small amount in blood, possible to reduce them to Hb by the methamoglobin-reductase enzyme
Hemoglobin transports oxygen to the cells and then
it is used in the terminal oxidation phase of the metabolic process
What factors can lead to increased methaemoglobin amount in blood?
- Severe oxidative damage tot he RBCs: ex. nitrites, free radicals, paracetamol, onion)
- Called Methaemoglobinaemia
What species are especially sensitive to ox. damage?
- Hb molecules of cats, newborns and very young animals are sensitive to oxidative damage
Methaemoglobinaemia, colour?
- Colour is dark brown and mucous membranes are deeply cyanotic
Rough estimation formula for Hb conc?
PCV (1/) / 3 x 1000 = Hbg (g/L)
RBC count methods?
- Burker chamber….
- Estimated RBC count; formula used if we suspect a normal average RBC volume
- RBC count measured by automatic cell counter
- Estimated RBC count; formula used if we suspect a normal average RBC volume
Ht L/L / 5 x 100 = RBC count x 10^12/L
- RBC count measured by automatic cell counter
- Based on electrical impendance change due to transmission of particles through an aperture -> electric flow -> size of RBC
- Shows RBC and thrombocytes
- X axis shows size, Y axis shows number counted
RBC size taken up by automatic cell counter
40-100fl (0-150)
Automatic cell counter, why should blood be warmed to 37 C before counting?
Because if the blood is cold-agglutinated the cells in the aggregrations will not be counted. Warm -> separates cells
Normal RBC count
4,5-8 x 10^12 /L
Tests to gain info about size, number, colour (the indices)
- Ht, PCV, RBC count, Hb concentration (objective info), blood smear if by good cytologist (can be very subjective)
- They are useful for humans, cats and dogs, but for horses and cattle the parameters of RBCs are varying too much, also within the individual
Mean corpusclar Haemoglobin (MHC) indicates?
MCH indicates average Hb content of RGCs
Mean corpusclar Haemoglobin (MHC) formula
Hb (g/L) / RBC count x 10^12/L = MHC (pg)
Mean corpusclar Haemoglobin (MHC), normal value?
12-30 pg
In young animals it can be increased 28-31 (MCV can also be increased)
Horse - 12-20
Ru - 8-17
Dog - 15-24
Cat - 13-17
Decreased MCH is called?
Hypochromasia
Increased MCH is called?
Hyperchromasia
Mean corpusclar volume (MCV) indicates?
MCV indicates the average size of the RBCs (macro, normo, microcytic)
Mean corpusclar volume (MCV) formula?
PCV / RBC count x 1000 = MCV (fl)
Mean corpusclar volume (MCV) normal values?
60-70 fl Horse - 37-58 Ru - 42-52 Dog - 63-75 Cat - 40-53
MCV, size og RBC in species, age, and some breeds
- Great heterogenity in size
- Cats, horses -> smaller RBC
- Young RBC -> large
- Newborns -> large
- Adults -> smaller
- Japanese Akita -> smaller
- Poodles -> very large
Some causes of microcytosis:
- Chronic blood loss
- Iron, copper, pyridoxine (vi. B6) deficiency
- Portosystemic shunt
Some causes of macrocytosis:
- Mostly regenerative anemias
- Polycythaemia absoluta vera (erythroleukemia)
- Vit. B12, folic acid, cobalt deficiency
- Erythroleukemias
Mean corpusclar Haemoglobin concentration (MCHC) indicates?
MCHC indicates the average concentration of haemoglobin in erythrocytes (hB concentration)
(hyper, normo, hypochromic RBCs)
Mean corpusclar Haemoglobin concentration (MCHC) formula?
Hb (g/L) / PCV = MCH (pg) / MCV (fl) x1000 = MCHC (g/L)
Mean corpusclar Haemoglobin concentration (MCHC) normal values?
300-350 g/L (30-35%) - normochrom
Horse - 31-37 %
Ru - 30-36 %
Dog - 32-36 %
Cat - 30-36 %
When MCV and MHC are low (ex. chronic liver failure) MCHC can be normal, however there is?
Anemic state
Decreased MCHC- hypochromasia causes:
- Newborn animals
- Regenerative anemias
- Iron deficiency anemia
Increased MCHC- hypochromasia causes:
- Erythroleukemia (polycythaemia absoluta vera)
- Vitamin B12, folic acid, cobalt deficiency
- Immunohemolytic anemia (spherocytosis-presence of blood in spherocytes)
- Lead poisoning
- Splenectomy
Increased MCHC- hyperchromasia causes:
- Erythroleukemia (polycythaemia absoluta vera)
- Vitamin B12, folic acid, cobalt deficiency
- Immunohemolytic anemia (spherocytosis-presence of blood in spherocytes)
- Lead poisoning
- Splenectomy
Typical changes in derivated parameter:
macrocytic, hypochromic; MCV-up, MCHC-down, (reticulocytes-up)
Regenerative anemias
Typical changes in derivated parameters: normocytic, normochromic; MCV-unchanged, MCHC-unchanged, MCH normal or decreased
Non regenerative anemias
Typical changes in derivated parameters: microcytic, hypochromic; MCV-down, MCHC-down, (decreased Hb synthesis)
Iron, copper, piridoxine deficiency anemias, liver failure, portosystemic shunt
Typical changes in derivated parameters: microcytic, normochromic; MCV-down, MCHC-unchanged
Normal for Japanese Akita
Typical changes in derivated parameters: macrocytic, normochromic; MCV-up, MCHC-unchanged, impaired DNA synthesis
FeLV infection, vitamin B12, CO or folic acid deficiency, erythroleukemia, poodle macrocytosis