Anaemia Flashcards
Define anemia
Reduction in the total circulating red blood cell mass below normal limits, formally diagnosed based on reduction in hematocrit and/or hemoglobin.
Results in reduced oxygen carrying capacity and tissue hypoxia.
How do anaemic patients tend to present?
Pale
Weak
Easily fatigued
What are the different mechanical based classifications of anaemia?
Blood loss
Inherited genetic disorders
Hemoglobin abnormalities
Acquired genetic defect
Mechanical trauma
Nutritional deficiencies
What is meant by hemolysis?
What are some common features?
Premature RBC turn-over and desitruction
Shortnend RBC lifespan less than 120 days
Elevated erythropoietin with increased erythropoiesis
Increased hemoglobin catabolites e.g bilirubin - jaundice is severely rare.
Can be intravascular (in the blood) or extravascular (macrophages in spleen and liver)
What are the precursor cells/processes for an erythroblast?
Pluripotent hematopoietic stem cell
Pronormoblasts (high nuclear to cytoplasm ratio)
Normoblasts aka erythroblast - dec ratio. Hb synthesis starts, cytoplasm shifts shape
Reticulocytes - has now lost nucleus and organelles (keep ribosomes)
Enters systemic circulation from bone marrow, looses rest of organelles matures into erythrocytes
Lives for 120 days
What are some secondary functions of RBCs?
Contribute to acid base homeostasis
Contain carbonic anyhdrase - catalyse reversible CO2 + H2O <–> H+ + HCO3-
Hb is an acid-base buffer
What are the consequences of increased RBCs - from surgical perspective?
Increased coagulation of blood - increased risk of MI, stroke etc
What regulates the production of RBCs?
Erythropoietin - released in response to tissue hypoxia from kidneys.
Smaller role of thyroid hormone and testosterone
Nutrients required = iron (for Hb), vitamin B12 and folate (for DNA synthesis)
What hemoglobin levels indicate anaemia?
<120 g/L in females
<140 g/L in males
How can anaemia be categorised by MCV?
MCV = average size of rbc
Microcytic = <80fl
Normocytic = 80-100fl
Macrocytic = >100Fl
What are some causes of microcytic anaemia?
Iron deficiency
Chronic inflammatory disease
Thalassemia
What additional investigations should be done for a normocytic anaemia?
Reticulocyte count
High count = hemolytic anaemia or blood loss, inc production as compensation
Low count = bone marrow disorder aka aplastic anaemia unable to produce
What are the different types of macrocytic anaemia?
What investigation should be done next?
Blood smear
1 - harge megaloblasts and hypersegemented neutrophils - VB12 deficiency, Folate deficiency, drug induced
2 - non megaloblastic = alcohol abuse, hypothyroidism, pregnancy
What conditions can decrease rbc production?
Bone marrow disorder
CKD - dec EPO
Hypothyroidism
VB12 deficiency
Iron deficiency
Chronic inflammatory disease - decrease iron levels and lifespan
What are some potential causes of increased rbc production?
Intravascular - mechanical heart valve, TTP and HUS
Extravascular - hypersplenism, inherited hemolytic anaemia (sickle cell), acquired hemolytic anaemia (malaria)
