Erythroid Flashcards
What are the components of blood?
- Fluid (plasma/serum)
- Ions
- Proteins
- (albumin, globulin)
- [colloid osmotic pressure]
- hormones
- mediators
- clotting factors
- nutrients
- Lipids
- Carbohydrate
- Gas
- Cells
What are the functions of blood?
Transport
- nutrients/oxygen
- removal of waste products
- hormones and other mediators
Ion buffer – fluid/electrolyte homeostasis
Coagulation
Thermoregulation
What are reticulocytes?
Young (immature/non-nucleated) erythrocytes prematurely released to blood from the bone marrow in regenerative anaemias.
How do you visualise reticulocytes?
New methylene blue (NMB) precipitation demonstrates
What appearance do reticulocytes have on romanowsky stain?
Polychromatophil
Bottom pic
What are the clinical applications of reticulocytes?
Evaluation of erythropoiesis in bone marrow
Differentiation of regenerative and non-regenerative anaemia
What is this?
Reticulocytes
What can be seen?
Clumps of ribosomal RNA & mitochondria
How can we count reticulocytes?
- Manual
- Automated
How do you calculate absolute reticulocyet count?
observed % reticulocytes x RBC (x1012/l) x 10
Reticulocytes in dogs:
A) How many is normal?
B) How many do we expect in regeneratve anaemia?
A) Low number of reticulocytes (<1%)
B) Expect at least (>60x109/L) in regenerative anaemias
Cat reticulocyte:
A) How many is normal?
B) What are the 2 morphological types?
C) Which is the only type we consider in regeneration?
D) How many do we expect in regenerative anaemia?
A) Low number of reticulocytes (0.2-1.6%)
B)
- ‘aggregate’ blue stained coarse clumping (0.5% of erythrocytes)
- ‘punctate’ small, blue stained dots (1-10%).
C) Aggregate in assessment of regeneration
D) Expect at least (>50x109/L) in regenerative anaemia
How many reticulocytes are in normal ruminant and horse blood?
Virtually none
When is the peak production of reticulocytes in cattle post blood loss?
7-14 days
What animal is this and why?
Dog
- Larger erythrocytes
- Uniform size
- Central pallor
What species is this and why?
Cat:
Smaller erythrocytes
Anisocytosis (variation in size)
Scarce central pallor (less concave)
What species is this and why?
Horse:
Rouleaux
(sedimentation tendency)
What species is this and why?
Ruminant
Anisocytosis and crenation
What is the blood variation in:
A) Poodles?
B) Akitas?
C) Greyhounds?
A) Macrocytosis
B) Small erythrocytes and high potassium
C) High PCV
How do we measure RBC size?
MCV (fL) – mean corpuscular volume
= PCV (L/L) X1000 / RBC count (1012/L)
What is normocytosis?
Normal range of RBC size
What can cause macrocytosis? (3)
- Regenerative anaemia
- FeLV infection
- Myeloproliferative disease
What can cause microcytosis?
Iron deficiency
What is red cell distribution width?
A numeric representation of the variability in RBC size
More sensitive than MCV
What is anisocytosis?
Unusual large variation in RBC size, eg if large numbers of microcytes or macrocytes (Increased RDW)
Is RDW or MCV more sensitive?
RDW
Macrocytsosis:
A) Where is it normal?
B) When is it commonly seen?
A) Poodle
B) Damaged or aged samples
Where do you see hypochromic macrocytosis?
Regenerative anaemia
What is normochromic macrocytoiss associated with?
Feline leukemia virus subgroup A infections in kittens & myeloproliferative disorders in dogs & cats
What is hypochromic microcytosis a marker of?
Altered iron metabolism
Name 2 conditions we see microcytosis
Iron deficiency – most common cause in dogs: occult blood loss form GI tract; neonatal piglets; blood loss through internal or external parasites
Dogs/cats with portosystemic shunts (liver defect)– effect on iron metabolism currently unknown
Where is it normal to have microcytosis?
Akitas
How can we measure the RBC colour?
MCH & MCHC
(Mean cell haemoglobin/concentration)
Is MCH or MCHC more useful at measuring RBC colour?
Why?
MCHC
Cell size is taken into consideration
How do you calculate MCHC?
MCHC (g/L) = Hb(g/L) / PCV(L/L)
How do you calculate MCH?
MCH (pg) = Hb(g/L) / RBC(1012/L)
What is it known as to have low Hg content?
Hypochromic
What is hypochromic?
Low MCHC = low hg content
What is a raised MCHC due to?
haemolysis, and may be seen artifactually in lipaemic samples
What is polychromasia?
Pinkish/grey colouration of large RBCs on a Giemsa stained blood smear
What is haemoglobin distribution width?
Hgb equivalent of RDW (Red cell distribution width)
In dogs what does an average of >10 polychromatic red cells per oil immersion field suggest?
Marked regenerative response
What is MCV?
Mean cell volume - average red cell size
What is RDW?
Red cell distribution width
- Degree of variation in red cell size
- Could be more small cells or more large cells or both
What is MCHC and how do you calculate?
Mean cell haemoglobin concentration
•Average haemoglobin concentration in cells
MCHC = Hgb/PCV
Complete this table
Hypochromic
Normochromic
Hyperchromic
Microcytic
Normocytic
Macrocytic
Hypochromic
Normochromic
Hyperchromic
Microcytic
Fe deficiency or PS shunts
?Analytic error – miscounting platelets
Not physiological: indicates lipaemia, sample haemolysis, in-vivo haemolysis or Heinz bodies
Normocytic
If anaemic often inflammation/
chronic illness
Macrocytic
Regenerative anaemia (or cell swelling in sample transport)
Rare (often virus associated) erythroleukaemia
What is poikilocytosis?
Alteration in cell shape
- abnormal erythropoeisis
- specific organ disfunction
What are these?
Codocytes or ‘Target cells’
What is the appearance of Codocytes or ‘Target cells’?
- Appearance of a target with a bullseye;
- central, hemoglobinized area surrounded by an area of pallor; periphery of the cell contains a band of hemoglobin
- Lacking normal biconcave cross section due to folding of cell membrane
When might Codocytes or ‘Target cells’ be seen?
Seen in iron deficiency anaemia, liver disease with cholestasis & after splenectomy of dogs.
What is the significance of Codocytes or ‘Target cells’?
Very little
What are these?
Acanthocytes (‘spur cells’)
What is the appearance of acanthocytes (spur cells) and why?
Rounded projections of variable diameter & length, unevenly distributed
= due to increase in membrane cholesterol or in association with RBC fragmentation
Where are acanthocytes seen?
Diffuse liver disease, splenic haemangioma, haemangiosarcoma or portosystemic shunts
High cholesterol diet
What are these?
Spherocytes (and normal RBC)
What do spherocytes look like? and why?
Small, densely staining spherical RBCs, lack central pallor
Small portions of the cell membrane may have been phagocytosed by mononuclear phacocytes; residual cellular tissue resumes the smallest shape possible – a sphere.
Where are spherocytes never seen and why?
Rarely recognized in cats since normal RBCs have less of central pallor than in dogs
What is the meaning of spherocytes being present?
Presence implies that erythrocytes have surface bound antibodies or complement
Indicator of immune-mediated haemolytic anaemia in dogs
Will be present in animals that have received transfusions – cells are damaged and foreign.
What are these?
Spherocytes - dog
What are these?
Schistocytes
What are the appearance of Schistocytes?
- Irregular, fragmented erythrocytes
- through mechanical trauma to circulating erythrocytes
Where are Schistocytes seen?
- Markers of disseminating intravascular coagulation (DIC) and other angiopathies
- Seen in immune mediated anaemia, thrombosis, splenic haemangiosarcoma, hypersplenis, glumerulonephritis, congestive heart failure, valvular heart disease, doxorubicin toxicosis and myelofibrosis
What are these?
Crenation (‘burr cells’)
What are Crenation (‘burr cells’)?
= RBCs with spiked projections of more uniform length
= “Echinocytes”
Where are Crenation (‘burr cells’) seen?
- Some normal in ruminants
- Rarely snake envenomation
- Occasionally in dehydration
- Mostly artefactual!
What is this?
Schistocytes - eythrocyte fragmentation
What is this?
Acanthocytes - Few irregular elongations of RBC border with rounded ends
What is this?
Crenation - Numerous pin-point projections
How do you confirm agglutination?
Mix 1 drop of blood with 1 drop of saline
= Agglutination will persist, rouleaux formation will disperse
What is this?
Rouleaux formation - - Clustering/agglutination of RBCs in standing blood
Where is rouleaux formation seen?
Normal finding in horses.
Indicates inflammation in small animals
Relates to increased “stickiness” of plasma with increased globulin content
What can cause agglutination?
Immune-mediated haemolytic anaemia
Mismatched blood transfusion
What causes Heinz bodies?
Oxidative damage
What are these signs of?
- Basophilic stippling
- Nucleated erythrocytes
- Howell-Jolly Bodies
Signs of regeneration
What are these?
Left - methylene blue
Right - Wright stain?
Heinz bodies
What are heinz bodies?
Irregular shaped, refractile inclusions
Consisting of oxidative denatured haemoglobin
When are heinz bodies seen?
- Increased numbers in paracetamol and onion toxicity and other oxidative compounds; more common in cats than in dogs
- Up to 10% of RBCs in normal cats
- In cats also commonly associated with diabetes mellitus, lymphoma and hyperthyrodism (but also wide range of other diseases
What are these?
Reticulocyte - RNA-protein complexes
What is seen?
Heinz bodies - Denatured Haemoglobin
What is this?
Basophilic stippling
What is basophilic stippling and what is it caused by?
- Multiple, small, dark blue, punctate aggregates in RBC
- In vivo aggregation of ribosome’s into small basophilic granules
- Caused by low levels of pyrimidine 5’-nucleotidase (P5N), enzyme that catabolizes ribosomes.
Where is basophilic stippling seen? (3)
In cats (more common) & dogs associated with intensely regenerative anaemia
Associated with lead poisoning (reduced P5N activity)
Normal in immature erythrocytes in ruminants (low levels of P5N are normal)
What is this?
Nucleated erythrocytes
(nRBC’s, metarubricytes, normoblasts)
What is see with Nucleated erythrocytes (nRBC’s, metarubricytes, normoblasts)?
Erythrocytes with remains of a nucleus
Where are nucleated erythrocytes seen?
Regenerative anaemia
- Early release of RBCs from bone marrow and extra-medullary haematopoiesis sites in response to hypoxia
In absence of anaemia
- Non functioning spleen
- Marrow damage
- In cats, in absence of polychromasia, indication of myelodysplasia or myeloproliferative disease
What is this?
Howell-Jolly Bodies
What is Howell-Jolly Bodies? What does it represent?
Refractile, single blueish bodies in RBCs of variable size
Representing nuclear remnants
Where are howell jolly bodies seen?
- Regenerative anaemia
- Splenectomy
- Suppressed splenic function
- Higher percentage seen in normal cats
What can be seen? Discuss its prescence?
What are the forms?
Babesiosis
- Tick born disease
- Intracellular
- Endemic in cattle
- Dogs: Babesia canis or B. gibsoni, rare in UK, imported
Uncomplicated or complicated forms:
- Haemolytic anaemia
- Systemic inflammatory response syndrome (SIRS), Multiple organ disfunciton syndrome (MODS)
What is this? What is he appearance? Where is it?
How do we diagnose?
Mycoplasma haemofelis
(Haemobartonella felis)
- Highly pleomorphic, appearing as chains, discs or rods
- On surface or embedded into RBC membranes
- Worldwide distribution
- Diagnosis confirmed by PCR
What does mycoplasma haemofleis cause? What are the signs?
- Heamobartonellosis or feline infectious anaemia
- Variable clinical signs including regenerative anaemia, pyrexia & malaise
How do you calculate PCV?
PCV = MCV x RBCC
Why might PCV be wrong?
- RBC’s miscounted
- Mistaken for platelets
- Aggregated into pairs and triplets
- MCV misleading
- Cell shrinkage or swelling
- Transport, tube filling
- Osmotic effects in machine
Why might there be a high MCHC?
- Not physiological to cram more Hgb into red cells than they will take
- Haemolysis (sample handling or intravascular)
- Lipaemia
Why might MCV be wrong?
- Swelling of transport
- Mis-identification – pairs and triplets, cross over with large platelets
- Cell shrinkage or expansion in sample e.g. hyperosmolar
- Will impact on calculated PCV/HCT
How can the rule of three error be picked up?
Look at MCHC
Hct (%) approx. = Hgb (g/dL) x3 (+/- 3%).
What do you evaluate with the erython?
–Is there inadequate, adequate or excessive red cell mass to deliver oxygen to tissues?
–Is there evidence of anaemia?
- Is there evidence of regeneration?
- What is the cellular character of the anaemia?
–Normocytic, normochromic, hypochromic, macrocytic
–Is there evidence of polycythaemia
•Relative or absolute?
PCV (Hct), RBCC and Hgb:
A) What are they measures of?
B) What are the affcted by?
A) Red cell mass and oxygen carrying capacity
B) Haemoconcentration
How might we classify anaemia?
- Based on MCV and MCHC
- Blunt measure - microscope visible findings may not be sufficient to push parameter out of reference range
- Normocytic normochromic
- Often anaemia of illness or pre-regenerative or occasionally non-regenerative
- Macrocytic hypochromic
- Classic highly regenerative
- Sometime cell swelling of transport
- Microcytic hypochromic
- Classic iron deficiency – chronic external blood loss
- Without anaemia – portosystemic shunts
What is polycythaemia?
Increase in PCV, Hb concentration and RBC count
What is relative polycythaemia?
Apparent increase in RBC due to a decrease in fluid in circulation (often increased total protein and albumin)
What is absolute polycythaemia?
True increase in RBC mass due to increased RBC production/release
What does the term Polycythaemia imply?
Term polycythaemia implies increased number of several haemopoetic cell lines (human), however dogs & cats with polycythaemia vera usually have normal neutrophil & platelet counts!
What is seen with Relative Polycythaemia?
PCV is increased but no increase in RBC production
When do you get relative polycythaemia?
Dehydration” (wáter or acellular fluid loss): = [eg vomiting, diarrhoea, polyuria, extensive Burns, adipsia, wáter deprivation]
Exercise, fear, excitement, severe pain - stress = Adrenaline secretion, splenic contraction and transient redistribution of RBC from the spleen to the circulation
How do you resolve Relative Polycythaemia?
After rehydration or removal of cause of splenic contraction
What is seen with Absolute Polycythaemia?
Increased RBC production
What is Primary Polycythaemia (polycythaemia vera)?
- Rare myeloproliferative disorder
- Abnormal response of RBC precursors
- Normal EPO levels
What is Secondary Polycythemia?
What is theEPO value?
- Chronic tissue hypoxia of renal tissues (low arterial pO2) due to:
- heart/lung diseases, high altitude, thrombosis, constriction of renal vessels
- Renal tumor or cysts [↑intra-capsular pressure]
- Increased EPO
What test do we do for:
A) Red cell mass?
B) Effective erythropoiesis?
C) Red cell size and variation?
D) Red cell haemoglobinisation?
E) Red cell shape and inclusions?
A) PCV/Hct, RBCC, Hgb
B) Size and colour, reticulocyte count
C) MCV, RDW
D) MCHC
E) Smear
