Red cell changes

• Red cells homeostasis


  The mature red cell is the product of an orderly set of differentiation and maturation steps beginning with the pluripotent stem cell
• Red cell homeostasis


  1. 1st Level involves several mechanisms acting in a hierarchal network of substances (cytokines)

  2. 2nd Level is a set of committed cells that eventually become erythrocytes, requiring stimulating actions of the hormones erythropoietin as differentiation proceeds, and preprogramming of certain genes where enzymes are required during the maturation phase of Erythropoiesis

  3. 3rd Level is the orderly 14-21 days sequence of differentiation and maturation that is influenced by the level of erythropoietin available

  4. 4th Level is the stage of 24 hours after losing the nucleus; the Reticulocyte is released into circulation as an immature erythrocyte, with remnants of nucleated precursors in the form of small amounts of polyribosome

  5. Part of these 24 hours is spent in the spleen during which time it is polished- some proteins are removed, RNA material progressively decline

  6. Other features of red blood cells relevant homeostasis are: Durability despite; no mitochondria, no ribosome, very limited metabolic activity, adaptation to circulatory stress
• The red cell environment


  Consists of; other cell, plasma and inner lining of the blood vessel, which offer: Mechanical stresses of circulation that include hydrostatic pressure and turbulence, shear stresses in the microcirculation, Biochemical stresses including osmotic and redox fluxes associated with travel through the collecting system of the kidney, the sluggish vascular beds of the spleen, muscle and bone, rapid changes in ambient oxygen pressure occurring in the lungs
• Homeostasis


  Is maintained by: Adaptive membrane structure, Pathways of intermediary energy metabolism and redox regulation, Ability to maintain the hemoglobin in a durable and non oxidized state
• Defective homeostasis


  Changes and complications are: Quantitative, Qualitative, Both
• The RBC represents a particularly important group of human cells as such, with relevance and consequences extend beyond the red cells and blood
• Causes of defect


  The defect may be due to: Red blood cell, Environment, Interactions between these two, which can arise due to: Inherited, Acquired
• Basis of changes


  Biochemical, physiological, physical interactions and influence, interacting with: Membrane, enzymes, Haemoglobin
• RBC vulnerability to changes


  Major content is the Haemoglobin - any defect of HB affects the cell, Lacks the organelles for protein synthesis - incapable of self repair, Life span is finite, shortened when environment becomes unfavorable or cells ability to cope with damaging extra cellular influences is impaired, Life span average 120 days - sequence and random breakdown, Aging: loss of certain enzymatic activity, Reduced membrane proteins and membrane during the physical trauma
• Laboratory aspects of Red blood cell changes


  The changes are initially approached by blood counting, Blood film examination, Various parameters make up the normal blood count and blood film
• Total blood count


  • WBC, RBC, Hb, MCV, MCH, Platelets, Reticulocyte count, ESR Erythrocyte sedimentation (ESR)
• ESR Erythrocyte sedimentation (ESR)


  A measure of the rate at which red cells subside when suspended in autologous plasma
• Blood film


  Blood film on glass slides usually stained with one of the Romanowsky Stains: May Grunewald Giemsa, Leishman, Giemsa, Wrights Stain
• Normal RBC Size


  Normal red cells are 7-8mm in diameter with minor variations, The nucleus of small lymphocytes are usually used for comparison, Uniform in size with a mean diameter of 8mm, Only mild variations in size (Anisocytosis) is seen
• Normal RBC shape


  Red cells in normal peripheral blood are circular, The red cell is described as a biconcave disc thick at the periphery and relatively thin at the centre, Changes in shape (Poikilocytosis) is seen
• Normal central palor


  The majority of normal RBC have a reduced intensity of 'color' at the centre, This covers less than one third of the cell
• Inclusions


  No inclusion is expected in red cells in normal states
• Changes in haematological framing


  Size: Anisocytosis suggest defect in the Haemoglobin, membrane or enzymes, May be accompanied by changes in the central palor, shapes and inclusions
• Microcytes


  Cells are small MCV, MCH low, Microcytes picture due to haemoglobin synthesis failure this may occur i.e. iron deficiency, a block in iron metabolism, Failure in protoporphyrin haemosynthesis, failure of globin synthesis or from crystallization of Haemoglobin
• Macrocytes


  Large cells MCV, MCH increased, The underlying defect appears to be biochemical leading to faulty DNA synthesis, Lesion may be at some point in pyrimidine or purime synthesis or inhibition of DNA polymerization, Causes: Vit B12 deficiency, folic acid deficiency, DNA defect due to any causes, These lead to Macrocytosis megaloblastic and non megaloblastic
• Shape changes (Poikilocytes)


  These occur when there is a defect in the rbc: Membrane, Enzymes Haemoglobin, Major consequence is haemolysis - haemolytic anaemia, Shape changes are many and are always significant
• Significant changes in shapes


  • Spherocytes, Oval/ Elliptocytes, Acanthocytes, Tear drop/pear shaped, Target cells, Sickle shaped, Helmet cells, RBC fragments
• Central Palour


  Common changes include Polychromasia, Bluish, reduced of absence of central Palour
• Shapes that are significant


  • Tear drop/pear shaped, Target cells, Sickle shaped, Helmet cells, RBC fragments
• Inclusions


  • Nucleated red cells, Stippling, Nucleus remnants, Parasites
• Resulting defects


  Erythrocytosis, Polycythaemia, Anaemia of various types