The Erythron Flashcards
What are the ways of testing for oygen-carrying capacity in blood?
Hb, Hct, RBC count
What are the 3 methods of determining the size of RBC’s? Why?
Hct, Hb, RBC count
- confirm degree of anaemias by looking at changes in the same direction and proportion
- determine the avg sie and colour
- unequal changes in 1 of 3 tests compared to the other 2 - determine if it is diagnostic
On rbc indics, how and what effects the MCV, MCHC, and MCH?
- Agglutination: increase MCV
- Storage: increase MCV, decrease MCHC
- Turbidity: increase MCH, increase MCHC
What are the parameters used to evaluate reticulocytes?
Number
Age
MCH
Reticulocyte Production Index (RPI)
What are the main features of an erythrocyte?
Anucleated & full of hemoglobin to carry oxygen
What regulations does an erythrocyte partake in?
Acid-base balance
Ion regulation
Managing oxidative stress
What are the 4 main characteristics of an erythrocyte membrane?
- ion transporters
- cytoskeleton
- surface glycoprotein antigens
- deformability & antigenicity
What pathways/pumps are part of the metabolism of an erythrocyte?
- Glycolysis
- Hexose-monophosphate pathway
- Methemoglobin reductase pathway
- NaK ATPase
When is a mitochondria present w/i an erythrocyte?
As a reticulocyte or earlier stages
What is the mitochondria used for in a reticulocyte?
- heme synthesis
- biosynthesis
- replication
What are the genetic and nutritional deficiencies in RBC metabolism?
- PFK
- PK?
- Methb Reductase
- Se-GPx
- Phosphate
- DPG
What mnemonic is used for the oxygen Hb dissociation curve and DPG? What does it stand for and what does it mean?
C O2
A cid
D PG
E xercise
T emperature
- shift right, deliver more oxygen to the tissues
- shift left, pick up more (aka holding onto more) oxygen
What is the Luebering-Rapoport Pathway?
A metabolic pathway in mature erythrocytes involving the formation of DPG
What does DPG do?
Regulates oxygen release from hemoglobin and its delivery to tissues
DPG is low in what species?
Cats, ruminants
DPG is high in what species?
Dog, horse, human, pig
What causes increases in DPG?
T3
PK Deficiency
PH increase
Hibernation
Anaemia
Hypoxia
Why don’t ruminants use DPG?
They have structurally distint HbF w/ high oxygen affinity that favors oxygen pickup from maternal circulation
Hct is mildly correlated to what?
Metabolic rate
What are the 2 ways that RBC’s die?
- Become senescent as membranes and enzymes fail w/ age –> cleared by splenic macrophages
- Rupture to release Hb so the Fe & globin are recycled & bilirubin is excreted
What are the 4 types of Plasma appearance?
Colourless
Icteric
Hemolysis
Lipemia
Fibrinogen is what factor in the coagulation cascade?
Factor I
Fibrinogen is increased in what processes?
Acute inflammation
Necrosis
What is the calculation to determine the concentration of fibrinogen?
[Prot (unheated)] - [Prot (heated)] = [fibrinogen]]
Why is lipemia less than ideal?
- interferes w/ spectrophotometric tests, refractometer TP, flame photometric measurements of electrolytes
- may cause haemolysis
What may cause liipaemia in a blood sample?
-recent meal
-pathology
What occurs during hemolysis?
Contents of RBC’s is released (ASTT, LDH, +/- K+, inorganic phosphate)
What does hemolysis interfere w/?
Photometric tests
Refractometer & enzyme measurements
What is bilirubin?
The breakdown product of heme from hemoglobin from senescent or damaged RBCs?
What organ does bilirubin travel to? How??
Bilirubin is transported to the liver, bound to albumin
How is bilirubin handled onceit reaches the liver?
It is conjugated w/ glucuronic acid in the liver for bile excretion b/c it is highly insoluble
What parameters are affected by bilirubin? How?
Increases [ ] of albumin, cholesterol, glucose, TP
Decreases [ ] of creatinine
Increases in Hct and TP =
Haemoconcentration (increase rbc in blood, decrease in plasma)
Increase Hct w/ normal TP =
Erythrocytosis (polycythemia) - high concentration of RBC in blood (thick blood!)
Decrease hct and TP =
Haemorrhagic anaemia - anaemia due to excessive bleeding when loss of RBC exceeds production
Decrease Hct, normal TP =
Haemolysis or bone marrow dz
What does an RBC count tell you?
Measures oxygen carrying capacity
Number of erythrocytes per L of blood
Using a neubauer haemocytometer, how do you do a RBC count?
- Count WBC in 4 primary corner squares and multiply by 50 to get cells/ microliter
- count RBC in 5 secondary squares of central primary square and multiply by 10,000 to get cells/microliter
Impedence counters rely on which principle?
Coulter principle
What do Laser flow cytometers do?
Detect & count individual cells in microdroplets as they pass thru a laser beam. The cells scatter light based on size, nucleus, and cytoplasmic contents
What is CHCM used for?
To flag lipemia & hemolysis by comparing against total hemoglobin and comparing size and color
What are red cell indices? What are they used for?
RBC count, PCV, [Hb], or direct measure by flow cytometry
Used in anaemic animals (except the horse) to classify anaemia as regenerative or non-regenerative
What metrics are used in red cell indices?
MCV, MCHC, MCH
What is MCV? What does it tell you?
- volume of avg RBC in femtolitres
- Microcytosis, normocytosis, macrocytosis
What does microcytosis suggest?
Copper & Iron deficiencies
What does macrocytosis suggest?
Regenerative anaemia
Non-regenerative anaemia
Myeloproliferative disorders
Folate deficiency
Poodles
Hereditary stomatocytosis
Hyperthyroidism in cats
Foetals/neonates
What causes spurious macrocytosis?
Augoagglutination of erythrocyte
Persistent hypernatremia
Prolonged blood storage prior to assay
Heparin treatment
What occurs in horses that receive heparin treatment for acute laminitis, thrombophlebitis, DIC?
Induces agglutination resulting in an increase in apparent MCV, decrease in RBC numbers
Microcytosis can be seen in what conditions?
Nutritional: Fe, Cu, B6 Def
PSS
Anaemia of inflammatory disease
Storage depletion of Fe from increased erythropoiesis
Hepatic lipidosis in some cats
Inhibitors of heme synthesis
SIADH
Genetic defects –> Thalassemia, Band 4.1 deficiency, Japanese/korean dogs w/o anaemia, familial dyserythropoiesis in English springer spaniels, hereditary elliptocytosis in dogs
When would you see spurious microcytosis?
severely anaemic patients
Persistent hyponatremia in dogs
What do erythrocyte volume histograms do?
Reveal increased numbers of microcytes or macrocytes even when MCV is normal
What additional info can be obtained from an erythrocyte histogram?
Hb concentration with individual cells –> identifying individual hypochromic cells
Cytogram of volume vs [Hb} of individual cells
How do you determine Red Cell Distribution Width (RDW)?
(STD of erythrocyte volumes/mean cell vol) x 100
What is the RDW?
Coefficient of variation of erythrocyte volume and an electric measurement of anisocytosis
Increased RDW demonstrates what possible conditions?
- Regenerative anaemias with increased numbers of large reticulocytes
- Fe deficiency anaemia with increased numbers of microcytes
- Erythrocyte fragmentation
- after blood transfusions w/ different sized cells
- Dyserythropoiesis
When is RDW spuriously increased?
- Erythrocyte agglutination
- Platelets counted in erythrocyte histogram of severely anaemic patients
What is MCHC?
Avg concentration of Hb in an RBC in g/L
How do you calcuulate MCHC?
[Hb] (g/L) / PCV (L/L)
MCHC is normally…
Hypochromic or normochromic